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Patterns of Phanerozoic carbonate platform sedimentation
Abstract
Carbonate platforms changed substantially in spatial extent, geometry, composition and palaeogeographical distribution through the Phanerozoic. Although reef construction and carbonate platform development are intimately linked today, this was not the case for most of the Phanerozoic. Carbonate production by non-enzymatic precipitation and non-reefal organisms is mostly responsible for this decoupling. Non-reefal carbonate production was especially prolific during times of depressed reef growth, balancing losses in reef carbonate production. Palaeogeographical distribution and spatial extent of Phanerozoic carbonate platforms exhibit trends related to continental drift, evolutionary patterns within carbonate platform biotas, climatic change and, possibly, variations in ocean chemistry. Continental drift moved large Palaeozoic tropical shelf areas into higher latitudes, thereby reducing the potential size of tropical platforms. However, the combined global size of carbonate platforms shows no significant decline through the Phanerozoic, suggesting that availability of tropical shelf areas was not a major control of platform area. This is explained by the limited platform coverage of low-latitude shelves (42% maximum) and occasional high-latitude excursions of platform carbonates. We speculate that reduced tropical shelf area in the icehouse tropics forced the migration of the many carbonate-secreting organisms into higher latitudes and, where terrigenous input was sufficiently low, extensive carbonate platform could develop.
... Lithosphere and geodynamic characteristics and information (Tables 1 and 2). The database is therefore biased and does not match the estimated global distribution of carbonate platforms and reefs during the Phanerozoic as estimated by Kiessling et al. [46] or Markello et al. [1] ( Figure 2). The analysis and discussions presented in this paper consider this bias. ...
... Geodynamic Settings. The stratigraphic distribution of CSS case studies spans over the whole Phanerozoic with a nonuniform distribution that is not strictly conformed to the estimated abundance of carbonate platforms at the global scale according to Kiessling et al. [46] (Figure 2). ...
... In principle, any geodynamic setting that provides a relatively flat initial topography situated in favorable shallow marine environments for carbonate production can promote the development of carbonate platforms ( Figure 12). Although these conditions are not exceptional in Earth's history, the development of carbonate platforms throughout the Phanerozoic is not uniform in time and space [1,15,46]. Moderate subsidence rates (<200 m/Ma) and low levels of terrigenous fluxes are the most critical parameters for ensuring the maximum 3D development of carbonate platforms in marine paleoenvironments favorable to carbonate factories (amongst others [2]). ...
This pilot study is founded on an exhaustive investigation of representative and well-documented cases (120) of carbonate systems during the Phanerozoic. We investigated the coupling between geodynamic settings and geometry, physiography, and stratigraphic architecture of carbonate platforms. The objective is to identify and quantify the impact of geodynamic controls on carbonate platforms and possible global trends during the Phanerozoic. Carbonate platforms are characterized in terms of geometry, stratigraphic architecture, time duration, preservation rate, progradation and rates of progradation, platform type, and thickness. Geodynamic parameters are characterized in terms of basin physiography, basement depth and type, tectonic setting, and subsidence origin. Relationships between carbonate parameters and geodynamic characteristics are investigated, leading to nine models of Geodynamic Carbonate Platforms. Passive margin is the most favorable geodynamic setting for the development of carbonate platforms in three dimensions. The continental crust hosts most of the carbonate platforms independently of time and geodynamic settings. Carbonate platforms developed above the exhumed mantle or oceanic crust (volcano) are the exception or very small and isolated. Global trends during the Phanerozoic of carbonate platform lateral extend, progradation, or thickness are tentatively interpreted in relation to geodynamic and eustatic parameters. The concept of spatial intersection between geodynamic and climatic windows favorable to carbonate platforms is introduced with its possible retroaction to the global carbon cycle.
... Jan Golonka returned to Poland after merger of Mobil with Exxon and started second stage of work on the palaeographic maps. The reef database was completed (Kiessling et al., 1999(Kiessling et al., , 2002(Kiessling et al., , 2003. This database is available to public at https://www.paleo-reefs.pal.uni-e ...
... Large areas of the south China Craton were under marine conditions. Dark, graptolitic shales originated in semi-isolated basins separated by the Jiangnan orogenic belt (Ronov et al., 1984;Shouxin and Yongyi, 1991;Chen et al., 1995;Cocks, 2001;Feng et al., 2001;Golonka, 2000Golonka, , 2002Kiessling et al., 2003;Golonka et al., 2006b;Yao et al., 2019). Argillaceous rocks changed laterally into carbonates and, in the north-western part of South China, into mixed, carbonatesiliciclastic sediments. ...
... During the late Silurian (Fig. 22, the Tunguska Basin began to decrease in size as a result of gradual regression. Shallowing accompanied by limited connections to an open sea, resulted in the sedimentation of dolomites and locally gypsum-bearing deposits (Ronov et al., 1984;Tesakov et al., 1998Tesakov et al., , 2000Chekhovich, 2002, 2004;Golonka et al., 2003, Kiessling et al., 2003. Northwards, normal marine conditions occurred in the Taimyr Basin. ...
This paper discusses the paleogeography and plate tectonics of the Silurian using five global and twelve regional scale maps. These maps illustrate the distribution of major
tectonic elements such as subduction zones, spreading centres, transform faults and main volcanic areas 435 and 425 Ma ago. The regional maps show the global paleogeographic configuration combined with palaeoenvironmental and palaeolithofacies distribution. The paleogeographic analysis shows that the continents of Gondwana, Laurentia, Laurussia, Siberia, South China and North China were separated by the Iapetus, Rheic, Paleoasian (Prototethys), Paleotethys, Panthalassa and Mongol-Okhotsk oceans. Spreading of the Rheic and Paleotethys oceans constituted the main Silurian extensional event. The Scythian-Turan-South Kazakhstan-Junggar-Tarim-North China chain of continents moved north-westwards, and this led to a gradual narrowing of the Paleoasian ocean. The Caledonian-Scandian orogeny that resulted from the collision of Baltica, Avalonia and Laurentia constituted the main convergent event during Silurian times.
... At the Late Triassic, the Supercontinent Pangaea still existed ( Figure 9). In the western Tethys, carbonate platform sediments have been deposited in low latitudes within 35° of both hemispheres (Kiessling et al., 2003;Golonka, 2007). At this time, the Paleotethys Ocean was almost closed due to the collision of the Indochina and Sibumasu blocks in its eastern part. ...
... Surrounding the ocean of the Cimmerian continents including Sibumasu block, carbonate platform sediments represented by limestone and dolomite have been deposited in the shallow marine shelf, slope, and deep ocean basins (Golonka, 2004). These areas belong to the low-latitude tropical climate zone (Kiessling et al., 2003). Although we do not have concrete paleomagnetic data for the position of Sibumasu block at Late Triassic, the Sibumasu block was located in low latitudes within 35° based on almost all of the paleogeographic map at this time (e.g. ...
... Although we do not have concrete paleomagnetic data for the position of Sibumasu block at Late Triassic, the Sibumasu block was located in low latitudes within 35° based on almost all of the paleogeographic map at this time (e.g. Kiessling et al., 2003;Golonka, 2004;Metcalfe, 2021;Scotese, 2021). In the western Tethys, the carbonate factory of the carbonate platform is characterized by microbialites, skeletals (foraminifers, molluscus, and algae), reefal, peloids, and oolite that are mostly representatives of shallow marine shelf environments. ...
Moderately-preserved Late Triassic (late early to early middle Norian) and Late Triassic or Early Jurassic radiolarians have been identified from two sections of limestone and dolomitic limestone, respectively in the Tha Sao area, Kanchanaburi Province in western Thailand. Previously these limestones have been assigned as the Permian because of the similarity of lithology without any fossil evidence. Section 1 is a succession of about 18 m in thickness, consisting of calcareous mudstone, micritic limestone, and dolomitic limestone, in ascending order. Section 2 is about 30 m in thickness and consisting of dolomitic limestone. Middle micritic limestone of about 10 m thick of Section 1 yielded diversified radiolarians. Dolomitic limestone of Section 2 yielded rare radiolarians from two levels. We identified radiolarians from five levels of micritic limestone and two levels of dolomitic limestone and totally identified 53 species belonging to 39 genera including two species of which generic position is uncertain and one new species Colum tekini Sashida and Ito sp. nov. At the Late Triassic time, the Tethys Ocean between Sibumasu and Indochina blocks almost closed due to the collision of these two continental blocks. Upper Triassic radiolarian-bearing limestones have been deposited in the eastern to western Tethyan areas within 35° of both hemispheres. The present radiolarian fauna is representative of low latitude Tethyan fauna. The faunal similarity between the eastern and western Tethys indicates the uniformity of the establishment of the low latitude fauna by the Late Triassic.
... Carbonate platforms provide valuable geological archives that result from the interplay of carbonate production and accumulation, and are intrinsically related to changes in the environmental and biotic conditions (e.g., Kiessling et al., 2003;Godet, 2013;Phelps et al., 2015). Carbonate platforms were widely distributed in tropical-temperate zone during the earliest Guadalupian (Fig. 1A) (Kiessling et al., 2003;Pomar and Kendall, 2008;Moore and Wade, 2013). ...
... Carbonate platforms provide valuable geological archives that result from the interplay of carbonate production and accumulation, and are intrinsically related to changes in the environmental and biotic conditions (e.g., Kiessling et al., 2003;Godet, 2013;Phelps et al., 2015). Carbonate platforms were widely distributed in tropical-temperate zone during the earliest Guadalupian (Fig. 1A) (Kiessling et al., 2003;Pomar and Kendall, 2008;Moore and Wade, 2013). However, during the late Guadalupian, the Permian Chert Event saw chert accumulation greatly expand at the expense of carbonate deposition (Murchey and Jones, 1992;Beauchamp and Baud, 2002). ...
... Thus, platform carbonates are overlain by cherts in the Guadalupian Series of western North America (Murchey and Jones, 1992;Beauchamp and Baud, 2002;Matheson and Frank, 2020a), Far East Russia (Ueno et al., 2005) and Transcaucasia (Leven, 1998). The main contributors to Permian carbonate platform formation were foraminifers, calcareous algae, along with microbes and reefbuilders (Kiessling et al., 2003). Studies of shallow-water carbonate platforms show a long-term decline in their area from the late Carboniferous to the Middle Triassic (Kiessling et al., 2000;Kiessling et al., 2003), although their coarse stratigraphic resolution prevents analysis of the Guadalupian biocrisis. ...
In comparison with the amount of study undertaken on the end-Permian mass extinction, the preceding Guadalupian mass extinction has received little investigation, even though it marks a significant biotic turnover associated with global environmental changes. During the earlier event, reef carbonate production shut down and was replaced by siliceous, mud-rich deposits (SRDs) in South China. However, changes in carbonate platform productivity during this epoch remain to be clarified. This paper presents sedimentological and conodont biostratigraphic investigations on the Guadalupian SRDs developed on the Yangtze Carbonate Platform (YCP) in central Guizhou. The findings are viewed in the context of Guadalupian sequence correlation of South China successions, which shows that the integrity of the YCP failed to match the platform tectonic evolution. The platform evolution saw the onset of major intra-platform depressions and the gradual onlap by SRDs along the platform margin. Stratigraphic correlation reveals that the platform experienced three phases of onlap by SRDs during the early Roadian, the late Wordian and the late Capitanian upwards. Platform carbonates re-expanded their extent following the first two phases, but not during the final phase. An evolutionary model is proposed for the Guadalupian carbonate platform, which follows the contemporaneous eustatic sea-level fluctuations. The partial drowning observed within the platform interior and increasing retreat along the platform margin could suggest an insufficient carbonate sediment supply shedding from the platform top during the Guadalupian. The variation in carbonate productivity raises our attention to the change in shallow-water carbonate factories, which is closely related to the fortunes of carbonate-secreting biota and environmental factors impacting the carbonate platform producers during the Guadalupian.
... The interplay between these diverse controlling factors of carbonate sedimentation at different temporal and spatial scales leads to a "conundrum" (Pomar and Hallock 2008). Predicting carbonate systems through space and time is, thus, challenging (Kiessling et al. 2003;Markello et al. 2008). The complexity of carbonate prediction is first related to the limitation of geological records due to both preservation and record, i.e., outcrop and subsurface, availability. ...
... Such a global trend is that carbonates are not randomly distributed in the world oceans, neither in the Modern nor in the past (Lees 1975;Kiessling et al. 2003;Schlager 2005;Markello et al. 2008;Michel et al. 2018). In the Modern, the worldwide distribution of marine carbonates relates to global oceanic circulation (Lees 1975;Nelson 1988;Kleypas et al. 1999;Schlager 2005). ...
... Dealing with environmental controls of local case studies and evolution through time of carbonate sediments, complex models were developed to understand the occurrence and type of carbonate deposits (Tucker and Wright 1990;Markello et al. 2008;Pomar and Hallock 2008;James and Jones 2015). In contrast, no simple conceptual model is available that provides a comprehensive picture of the spatial pattern of carbonates against an integrated environmental parameter trend at a global scale; with the exceptions of distributional studies of geological records (Opdyke and Wilkinson 1993;Kiessling et al. 2003;and Markello et al. 2008) and specific studies in the Modern about Mediterranean red algae (Martin et al. 2014) and about coral reefs (e.g., Kleypas et al. 1999;Couce et al. 2012;Jones et al. 2015). The early spatial models of Lees and Buller (1972) and Lees (1975), however, greatly started the challenging spatial modelling of different carbonate associations against marine environmental parameters that are temperature and salinity (also cf. ...
Shallow-water carbonates are a major component of the Earth System but their
spatial distribution through geological times is difficult to reconstruct, due to the
incompleteness of the geological record, sampling heterogeneity and their intrinsic
complexity (i.e. the “conundrum” of Pomar & Hallock, 2008). Beyond this complexity,
carbonates are not randomly distributed in the world oceans, neither in the modern nor in
the past, and thus, global trends exist. In the present review, we focus on the understanding of the spatial distribution of carbonate production that is controlled by ambient environmental conditions at a global scale. A deterministic approach is used, which focuses on discriminating components, stratigraphic architectures and environmental features to relate shallow-water carbonate production (i.e. carbonate platforms) to sea-surface oceanographic parameters (temperature SST, salinity SSS and marine primary productivity). This approach allows determination of different carbonate factories and classifying sedimentary case studies. The scheme is designed to be applied in the geological record.
The work is based on extensive, mostly unpublished literature reviews on marine
carbonate platforms. Ecological niche modelling coupled with deep-time general circulation models (i.e. MITgcm) are used to calibrate a predictive tool of carbonate factory distribution at a global scale. A carbonate factory function is set up that is based on oceanographic parameters (i.e. SST, SSS and marine primary productivity). The model was tested using remote-sensing (AquaMODIS) and in situ (GLODAPv2) oceanographic data of Modern times, while outputs of paleoceanographic models are utilized for Lower Aptian (Cretaceous) modelling.
Four marine and neritic carbonate factories were defined that are called the marine biochemical factory, the photozoan factory, the photo-C-factory and the heterozoan factory. The model simulates the global distribution of Lower Aptian and Modern shallow-water carbonates that shows ca. 80 % fit to bibliographic reference points. Carbonate factories appear to thrive for specific ranges along the environmental gradient of carbonate saturation. This conceptual scheme appears to be able to provide a simple, universal model of paleoclimatic zones of shallow-water marine carbonates.
Tectonic processes compete as a regional controlling factor that cannot be predicted
at a global scale (e.g. initial topography) and create large heterogeneities in sedimentary
profiles and stratigraphic architectures. An exception of this pattern is the biochemical
factory for which tectonic processes (e.g. convergence zones) define the sedimentary profile (e.g. homoclinal ramp of a foreland basin) and associated paleoceanographic conditions (i.e. production under relatively restricted paleoceanographic conditions).
... (b) Interaction between arc volcanoes and (buried) carbonate platforms has been shown to increase CO 2 liberation from carbonate rocks. Present-day cool-and warm-water reefs (UNEP-WCMC, 2018) in magenta and ancient carbonate platform systems are in light green (Kiessling et al., 2003;Pall et al., 2018). (c) Present-day distance histogram between subduction-related volcanoes and subduction zones (see Supporting Information 1.1) F I G U R E 2 Reconstructions of active carbonate platforms (green) in the study by Matthews et al. (2016) as adapted from Kiessling et al. (2003) and presented by Pall et al. (2018) and updated in this study. ...
... Present-day cool-and warm-water reefs (UNEP-WCMC, 2018) in magenta and ancient carbonate platform systems are in light green (Kiessling et al., 2003;Pall et al., 2018). (c) Present-day distance histogram between subduction-related volcanoes and subduction zones (see Supporting Information 1.1) F I G U R E 2 Reconstructions of active carbonate platforms (green) in the study by Matthews et al. (2016) as adapted from Kiessling et al. (2003) and presented by Pall et al. (2018) and updated in this study. The interaction between subduction zones (teethed lines) and carbonate platforms within 436 km away from the trenches, in the overriding plate, is tracked through time in the workflow presented here. ...
... The carbonate platform maps from Kiessling et al. (2003) were georeferenced and reprojected into geographic coordinates, and using GPlates, the geometries were forward-rotated into present-day geometries -allowing the platforms to be connected to any plate tectonic reconstruction ( Figure 2) (Supporting Information 1.3). Given that carbonate platforms tend to accumulate on continental margins, and are also 'consumed' in decarbonation processes during arc volcanism, it is difficult to know how much a carbonate platform is eroded, buried, or consumed during volcanism and tectonism. ...
Abstract Plate tectonics, as the unifying theory in Earth sciences, controls the functioning of important planetary processes on geological timescales. Here, we present an open‐source workflow that interrogates community digital plate tectonic reconstructions, primarily in the context of the planetary deep carbon cycle. We present an updated plate tectonic reconstruction covering the last 400 million years of Earth evolution and explore components of the plate–mantle system that is involved in the exchange and storage of carbon. First, the workflow enables us to estimate subduction zone lengths through time, which represent the “tap” of carbon that is released at convergent tectonic margins. Second, we explore the role of Andean‐style versus intra‐oceanic subduction regimes during Pangea assembly and breakup. Third, we provide an improved model for carbonate platform evolution since the Devonian and evaluate the interaction of subduction zones and buried carbonate platforms. Last, we present a new model for estimating oceanic age, carbon content in the upper oceanic crust, and estimated (carbon‐containing) sediment thicknesses through time and present methods to track the subduction of this material through time. These components of the deep carbon cycle are key mechanisms controlling, or at least modulating, atmospheric CO2 on geological timescales and hence strongly influencing long‐term climate. We find that the mid to Late Cretaceous greenhouse climates were likely driven by increased subduction fluxes of volatiles and increased subduction zone interactions with carbonate platforms in the Tethyan tectonic domain. Our work highlights the importance of community digital plate tectonic reconstructions as a framework for studying key systems, such as the deep carbon cycle, that influence the life‐support mechanisms on our planet.
... Importantly, the abundances of the two facies types do not follow one another exactly, particularly in the early Paleozoic (Cambrian-Devonian) where tepees are abundant but pisoids are scarce. Note that the total deposits in each bin do not necessarily reflect the total extent of carbonate platforms throughout the Phanerozoic as estimated by Kiessling et al. (2003). ...
... The abrupt decline in tepee and pisoid facies coincides with the mid-Mesozoic Revolution. (c) Data on estimated extent of carbonate platforms throughout the Phanerozoic (gray boxes, Kiessling et al., 2003) and sea level (solid line, Haq et al., 1988). Also shown are reference trends for calcite/aragonite seas (Stanley & Hardie, 1998), tectonics (Crowley et al., 1998), and climate (warm in black bars, cool in white bars; Scotese et al., 2021). ...
... Note that over the range of Phanerozoic values used here, the porewater-equilibrium and surface water-kinetic models can be treated as firstorder functions of alkalinity and Ω calcite respectively (Figures 3a and 3b) despite the dependence on other factors such as mineralogy and temperature. level curve of Haq et al. (1988) as a proxy for total shelf area; the maximum values for surface water Ω calcite (Figure 5d) coincide with the Phanerozoic minimum in sea level from the mid-Permian to mid-Jurassic ( Figure 4c) An independent estimate of carbonate platform area from Kiessling et al. (2003) shows similarly low values during this period (Figure 4c). By the same logic, the maximum in relative pisoid abundance during the mid-Permian to mid-Jurassic (Figure 5b) can be explained if Ω calcite strongly depends on shelf area. ...
Ocean chemistry and carbonate sedimentation link Earth's climate, carbon cycle, and marine pH. The carbonate system in seawater is complex and there are large uncertainties in key parameters in deep time. Here, we link sedimentary textures formed in arid coastal environments and preserved in the rock record to past seawater carbonate chemistry. Prior to the mid‐Mesozoic, tepee structures and pisoids – features associated with peritidal environments – co‐vary with available shelf area during cycles of supercontinent formation and rifting. In contrast, tepees and pisoids are consistently scarce after the mid‐Mesozoic, which coincides with a radiation in pelagic calcifiers as well as the breakup of Pangea. Numerical models suggest that the global and temporal abundances of tepee structures and pisoids are correlated with secular shifts in seawater chemistry, and that trends likely reflect the underlying influence of tectonics and biotic innovation on marine alkalinity and the saturation states of carbonate minerals. As independent sedimentary proxies, tepees and pisoids serve as benchmarks for global carbon cycle models and provide a new proxy record of seawater chemistry that can help discern links among tectonics, biotic innovation, and seawater chemistry.
... Different types of basins formed depending on the orientation difference between the weak zones and the stress related to the regional E-W extension (Chakraborty et al. 2003;Mukhopadhyay et al. 2010). During the Mesozoic era, the Indian subcontinent had migrated from below the 30º S latitude to near the equator (Kiessling et al. 2003;Golonka 2011;Hall 2012). Throughout the Mesozoic era, climatic conditions varied as a function of overall global climatic changes and movement of the Indian subcontinent towards the equator. ...
... According to the paleogeographic reconstructions during the start of Mesozoic era, the Indian subcontinent was in a very different orientation from the modern position. In the Early Triassic (237 Ma) epoch, the paleoposition of India was below 30º S latitude (Mcloughlin 2001;Scotese 2002;Kiessling et al. 2003;Golonka 2011). The N-S of modern India was then oriented towards NE-SW. ...
... The N-S of modern India was then oriented towards NE-SW. During the Late Triassic period (Carnian to Rhaetian), the western end of the Indian subcontinent was at about 20º-25º S latitude and the eastern end was at about 45º-50º S (Kiessling et al. 2003;Golonka 2007Golonka , 2011Metcalfe 2013). During Early Jurassic, the western end was near 15º S latitude and the eastern end was near 35º-40º S latitude. ...
The Indian Gondwana basins preserve a thick sedimentary deposit from Carboniferous to CretaceousCretaceous. In India, the Gondwana sediments were mainly deposited in four intracratonic basins, i.e. Pranhita-Godavari (PG), Satpura, Son-Mahanadi and Damodar essentially in a fluviatile setting. While the PG Basin preserves the most continuous sedimentary history, MesozoicMesozoic basins at the west coast, including Kutch, Barmer, Jaisalmer, Saurashtra, record sedimentation from the JurassicJurassic period. During the MesozoicMesozoic era, there was a gradual shift in the climatic condition, which got reflected in the sedimentation pattern and fossil record. The Early Triassic sediments of the peninsular basins were deposited under warm to semi-arid climatic conditions in an essentially fluvial setting. The PG and Rewa basins record the global Triassic redbeds, having similar seasonal conditions, evidence of freshwater carbonates, along with profuse terrestrial fauna and flora. The Early JurassicJurassic sediments of Barmer and Jaisalmer were essentially deposited in fluvio-lacustrine environment under humid climatic condition. With the advent of Middle JurassicJurassic, limestone started depositing in the MesozoicMesozoic basins. The Middle to Late Jurassic sediments of the western coastal basins were deposited primarily in shallow marineShallow marine environment. Gypsum formed under fluvio-lacustrine setting in PG and Rewa basins, while it formed under shallow marine conditions in Kutch and Jaisalmer basinsJaisalmer Basin. By the Early CretaceousCretaceous, oceans began to separate the major fragments of the GondwanalandGondwanaland, which led to the extensive deposition of mostly marginal marine to shallow-marine sediments all along the western coastal basins of India. Whereas the Gondwana basins record a few fluvial successions, having profuse vertisol profiles. Deccan traps overlie the MesozoicMesozoic sedimentary successions of the Gondwana basins, while the Cenozoic sedimentation continues at western coastal basins. This work attempts the correlation of MesozoicMesozoic basins of India and points out areas of future research.
... Carbonate platforms in the early Palaeozoic developed mostly in the tropical to sub-tropical shallow-marine realms (Kiessling et al. 2003). Cambrian platform carbonates were mainly composed of non-skeletal allochems such as ooids and peloids with abundant microbial buildups (e.g., Webby et al. 2004;Pruss et al. 2010;Pratt 2010;Chen et al. 2011Chen et al. , 2014Pratt et al. 2012;Lee et al. 2015). ...
... Cambrian platform carbonates were mainly composed of non-skeletal allochems such as ooids and peloids with abundant microbial buildups (e.g., Webby et al. 2004;Pruss et al. 2010;Pratt 2010;Chen et al. 2011Chen et al. , 2014Pratt et al. 2012;Lee et al. 2015). By the Early to Middle Ordovician, the Great Ordovician Biodiversification Event (GOBE) resulted in a sharp increase in both diversity and abundance of carbonate-secreting biota (Kiessling et al. 2003;Webby et al. 2004;Pruss et al. 2010). This led to a major change in carbonate depositional systems; for example, the importance of skeletal grains and reefs in carbonate platforms increased, whereas non-skeletal grains and microbialites diminished Droser 1997, 1999;Liu 2009;Pruss et al. 2010;Liu et al. 2011;Wright and Cherns 2016;Lee and Riding 2018). ...
... The South China Block was located in a tropical realm of peri-Gondwana during the Late Ordovician (Kiessling et al. 2003;Torsvik and Cocks 2017;Scotese and Wright 2018) and consisted of four major geographical regions; these are, from northwest to southeast, the Yangtze Platform, the Jiangnan Slope, the Zhujiang Basin, and the Cathaysian Land Zhan et al. 2002;Li et al. 2004;Zhang et al. 2007;Chen et al. 2018). The Zhe-Gan Platform is suggested to have developed in an intracontinental basin of the Zhujiang Basin during the Late Ordovician ( Fig. 1a; Zhan et al. 2002;Li et al. 2004;Zhang et al. 2007). ...
The Upper Ordovician Zhe-Gan Platform was a short-lived carbonate platform that formed near the northern margin of the Cathaysian Land of the South China Block. The Zhe-Gan Platform is less well understood than the adjacent Yangtze Platform due to the absence of detailed sedimentological study as well as the structural complexity of the area. The aim of this study was to reconstruct the Zhe-Gan Platform based on detailed facies analysis of the middle to upper Xiazhen Formation. A total of 24 shallowing-upward depositional cycles (C1–24) are identified and subdivided into three types based on the vertical association of facies: (1) mixed carbonate–clastic subtidal cycles; (2) carbonate subtidal cycles; and (3) peritidal-capped subtidal cycles. The reconstructed depositional model indicates a ramp-type, mixed siliciclastic–carbonate platform, generally similar to other Late Ordovician carbonate platforms characterised by dominant skeletal grains, less common ooids, and an absence of skeletal barrier reefs. The newly developed Late Ordovician ramp-type carbonate platforms could have been induced by the evolution of skeletal organisms and the accompanying palaeoceanographic changes prior to the Hirnantian glaciation. The complex palaeogeography of the South China Block would have influenced the co-occurrence of the Xiazhen carbonate platform and black shales of the adjacent Yangtze Platform on the same block during the Late Ordovician.
... Throughout the Cretaceous, important carbonate shelves were formed in the Tethyan region, which, alongside reefs, are the main sites of preserved carbonate production in the sedimentary rock record (Kiessling et al. 2000). These shelves contain important information about changes in marine biota, depositional facies, diagenesis and climatic events (Simo et al. 1993;Kiessling et al. 2003). Furthermore, their large petroleum reservoirs make up a significant amount of all the oil produced in the world (Wilson 1975;Roehl and Choquette 1985). ...
... Furthermore, their large petroleum reservoirs make up a significant amount of all the oil produced in the world (Wilson 1975;Roehl and Choquette 1985). Marine carbonate deposits are directly controlled by palaeogeography and palaeoclimatic conditions; thus, their rocks can show trends in the evolutionary patterns of their preserved biota over time (Kiessling et al. 2003). The main carbonate-producing elements during the Cretaceous are foraminifera, algae, molluscs, echinoids and rudists, as well as oolitic, oncolitic and peloidal grains (Wilson 1990;Philip et al. 1995;Masse et al. 1998;Wilmsen 2000). ...
During the Early Cretaceous, several extensive carbonate shelves were developed in the sedimentary basins located on the Central Segment of the South Atlantic Ocean. These marine successions are characterized by mixed carbonate and siliciclastic sediments with a diverse fossil content, deposited during the late Aptian–Albian interval. The microbiofacies content of two continuous cores (SER-01 and SER-03), each approximately 200 m deep, drilled in the onshore region of the Sergipe–Alagoas Basin, north-eastern Brazil consists of mudstones, wackestones, packstones, grainstones, rudstones, marls, claystone, shales and sandstones in Core SER-01, whereas those from Core SER-03 are essentially fine-grained lithologies such as mudstones, wackestones, claystone and shales. Two low-frequency sedimentation cycles are identified, with SER-01 being characterized by restricted and shallow-marine facies that grade up in a transgressive trend, which is also present throughout Core SER-03. Six microfacies are recognized, indicating deposition in a high-energy shallow-marine environment with a sand-bar system, which later evolved into a low-energy deeper-marine environment (outer shelf). The microfossil content includes planktic and benthic foraminifera, which are dominant in both cores, as well as macrofossils such as echinoderms and molluscs. Cadosinids, green algae, microcrinoids and inoceramids occur locally in both cores. In addition, Core SER-01 is characterized by abundant microbial units. The fossil content shows palaeogeographic affinities with the Tethyan Realm. These records suggest water connections between the South Atlantic and the North Atlantic/West Tethys Sea since the late Aptian interval.
... Though oysters colonized both hard and soft substrates (Seilacher et al., 1985;Machalski, 1998;Kidwell and Brenchley, 1994;Anderson et al., 2004), they are typically encrusting fauna of rocky shores from the Mesozoic (i.e., Johnson, 1988a;Zítt and Nekvasilova, 1996;de Gibert et al., 1998de Gibert et al., , 2012Baarli, 1999, 2012;Betzler et al., 2000;D'Alessandro et al., 2004;Sørensen and Surlyk, 2008;Bover-Arnal et al., 2011;among others), even present in K/P rocky shore successions (i.e., Sanders, 1998). In this sense, Late Cretaceous carbonate platforms reached high latitudes in the northern and southern hemispheres (Kiessling et al., 2003), with benthic carbonate factories dominated by bivalves (oysters), echinoids, bryozoan, brachiopods, and red algae (i.e., Surlyk and Christensen, 1974;Surlyk, 1997). Oysters are considered as habitat-forming species or ecosystem engineers that enhance the biodiversity from attenuation wave energy, improvement of water quality by biofiltered, creation of habitats for fish species, and support of a wide diversity of epibenthic invertebrates (Newell, 1988;Coen et al., 2007;Grabowski and Peterson, 2007;Parras and Casadío, 2006;Padilla, 2010;Gutiérrez et al., 2011;Bayne, 2017;Coen and Humphries, 2017;McAfee et al., 2017). ...
... This example is partially synchronous (Late Cretaceous-Danian) with one of the largest and longest-lived cool-water carbonate platforms occurred in the Baltic Shield (Surlyk, 1997), mainly conformed by oyster bank communities along the rocky shorelines. The inclusion of the K/P cool water carbonate sedimentation over Patagonia in the worldwide carbonate platform reconstructions (i.e., Kiessling et al., 2000Kiessling et al., , 2003 will extend its distribution to higher latitudes and would increase the global carbonate production (70-140 km 3 ). ...
The Atlantic Maastrichtian-Danian (K/P) transgression over northern-central extra-Andean Patagonia
(Argentina) covered both Mesozoic sedimentary basins and the Northpatagonian Massif (NPM). The flooding
of the NPM resulted in a regional unconformity/nonconformity (70.000 km2) between the pre-Cretaceous basement
(Jurassic Chon Aike Silicic Large Igneous Province and igneous-metamorphic Paleozoic basement) and the
K/P marine transgressive record, constituting the widest known ancient rocky shore of South America
(Northpatagonian rocky shore).
The transgressive stratigraphic record over the basement is mainly composed of isolated carbonate bioclastic deposits
up to 40m thick with predomination of bivalves, echinoderms, bryozoan, coralline red algae, and foraminifera
skeletal remains;we interpreted these bioclastic near-shore deposits as rocky shore associations. The hard
substrate, irregular seacoast and low accommodation space over the NPM provided a preferential ecological
niche for encrusting biota (i.e., Oyster reefs) during the K/P epicontinental flooding. The colonization of “engineer
ecosystems” organisms over thousands of square kilometers probably enhanced the coastal biodiversity. The K/P
Northpatagonian rocky shore favored the conformation of a short-lived, transgressive, cool-water carbonate factory
in the south-eastern extreme of South America.
... These models only considered extrinsic factors and explicitly excluded changing biota with different carbonate-production rates. Dutkiewicz et al. (2019) reconstructed neritic carbonate-accumulation fluxes using the extent of carbonate platforms (Kiessling et al., 2003;Fig. 9e), and preservation rates of Bosscher and Schlager (1993). ...
... An example of the time scales involved in such analyses are data and model-derived estimates of surface areas of carbonate platforms (Kiessling et al., 2003;Pohl et al., 2019), neritic carbonate-preservation rates (Pohl et al., 2020), which reflect flooded continental areas (Cao et al., 2017), and ultimately first-order Cretaceous sea level change (Figs. 7,9). ...
... As one of the two major tectonic units forming the South China Paleoplate, the Yangtze Block comprised the Yangtze and Jiangnan regions ('Yangtze Platform' and 'Jiangnan Slope' sensu Chen and Rong, 1992), until the platform-slope-basin palaeogeographic pattern was disrupted during the late Katian due to the Kwangsian Orogeny (Chen et al., 2014;Chen et al., 2018). During the Middle to early Late Ordovician, the Yangtze region was covered by a broad epeiric sea in low latitudes (Johnson et al., 1989;Torsvik and Cocks, 2017;Cocks and Torsvik, 2021), similar to most platforms at that time (Kiessling et al., 2003). The study area (Fig. 1) is located in the western Yangtze region (present-day orientation), and was surrounded by emergent landmasses (Wang et al., in press). ...
... The discovery of these warm-water limestones in the Qiaojia area is not only a useful supplement to the extent of known tropical-subtropical carbonate platforms during late Middle-Late Ordovician (e.g., Kiessling et al., 2003;Yu et al., 2019), but also provides a unique window to investigate palaeo-environments. For example, starting from the Middle Ordovician, warm-water oolites decreased and were then replaced by bioclastic limestone in Laurentia (James et al., 1989), where a warm-water, ooid-bearing succession of Late Ordovician age has recently been reported (James et al., 2020). ...
The Middle–Late Ordovician Nuoduo and Huadan formations are well exposed at Songliang of northeastern Yunnan Province, representing rare neritic carbonate sediments deposited in the Yangtze region, South China during that time. Detailed sedimentological analyses support the recognition of ten microfacies from the succession, including shale (MF 1), argillaceous mudstone/dolostone (MF 2), mollusk-ostracod wacke-packstone (MF 3), peloidal wacke- to pack-grainstone/dolostone (MF 4), ooid-cortoid-peloid pack-grainstone/dolostone (MF 5), peloidal bindstone (MF 6), bioclastic wacke- packstone (MF 7), green algae mud-wackestone to floatstone (MF 8), bioclast-lithoclast float-rudstone (MF 9) and green algae bindstone (MF 10). Types A, B and C of shallowing-upward sequences are constructed according to vertical associations of MFs. The Nuoduo Formation mainly comprises Type A and Type B, both being characterized by abundant peloids, ooids, cortoids and aggregate grains. MF 5 and MF 6 cap the Type A and Type B sequences, respectively, suggesting an overall restricted marine environment shifting cyclically from lagoon to shoal, or lagoon to tidal flat, respectively. Type C sequences, occurring in the topmost Nuoduo to Huadan formations, contain various green algae indicative of open-sea, euphotic subtidal zones. The transition from A and B to C sequences is marked by ferruginous ooidal intervals, possibly correlated to relative sea-level rise and/or tectonic activities. A continuous neritic, warm-water environment is proposed for this area from late Middle to Late Ordovician, with the Nuoduo Formation filling the absence of warm-water deposits in the tropical or subtropical Yangtze region during Middle Ordovician. The increasing diversity and abundance of green algae in the Huadan Formation might represent a global radiation event of marine flora during the studied interval. Unique fossils and environments distinct from those of the interior Yangtze region are documented here, leading to a better understanding of the Ordovician System regionally and globally.
... However, to understand the effect of increasing primary productivity in the oligotrophic eastern Tethyan carbonate-dominated coastal ocean on the carbon cycle during the PETM, a conservative mass balance estimation has been performed. In doing so, the area of the eastern (particularly southern part) Tethyan carbonate platform ~1.8*10 6 Km 2 was estimated from Fig. 10A of Kiessling et al. (2003). The average thickness of the PETM carbonate interval of ~10 m was deduced from the reported thickness of the PETM CIE interval from 9 sections spread across the eastern Tethys (Supplementary Table 2). ...
... Considering a conservative 0.01% TOC (minimum value found in the present study), ~50,000 Gt oligotrophic eastern Tethyan coastal carbonate alone is capable of sequestering ~500 Gt C during the ~200 Ka PETM interval (see supplementary materials for details). This ~500 Gt C sequestration in the oligotrophic eastern Tethyan coastal carbonate, occupying ~18% of the Paleocene-Eocene carbonate coastal area (~10*10 6 Km 2 ; Kiessling et al., 2003), is highly significant if one considers that the total carbon addition to the exogenic carbon cycle was ~4500 Gt C (Elling et al., 2019) during the PETM interval. Therefore, oligotrophic coastal carbonate, even though neglected in the carbon sequestration modeling, can act as an important carbon sink during the PETM. ...
The coastal upwelling zones, occupying only ~0.5% of the global ocean, account for ~10% of the global primary productivity. The CO2 fixation by primary producers amplifies in the upwelling zones during global warming due to the higher nutrient supply. Based on the presumption that the nutrient-deficient coastal ocean is less productive, the state of the oligotrophic coastal ocean is often neglected in the productivity-climate change studies. The present study investigated the changes in the primary productivity, redox condition, and nutrient content, using algal abundance, total organic carbon, and various major, trace, and rare earth elements with yttrium (REY) proxies, of the oligotrophic equatorial eastern Tethyan coastal ocean across the Paleocene-Eocene Thermal Maximum (PETM), a prominent paleo-global warming event. Despite the lower nutrient (lower NiEF, CuEF, and ZnEF) contents, and invariable salinity, pH, and light conditions, the PETM interval shows extensive growth of coralline red algae in the hypoxic-oxic water column. Based on these observations, and inferences drawn from the previous laboratory experiments, conducted on the algal growth in varying pCO2 by others, we postulate that the increased atmospheric CO2 concentrations during the PETM probably enhanced the primary productivity of the oligotrophic Tethyan coastal ocean. If so, then the oligotrophic coastal ocean may be considered as an effective CO2 sink and likely to play a pivotal role in carbon cycle-climate connection studies.
... The Central Mediterranean hosted several large (>100 km) carbonate platforms from the Mesozoic to the Paleogene (Kiessling and Golonka 2003). Carbonate ramps developed along the North African continental margin from Tunisia (Racey 2001) to Libya (Swei and Tucker 2012) whereas isolated carbonate platforms aggraded in pericratonic settings, e.g., the Hyblean platform of SE Sicily (Grasso and Lentini 1982), Apulia (Bosellini 2006), Panormide (Zarcone and DiStefano 2008) and Malta ( Fig. 1 b), although a better understanding of facies distribution is required in the last case to reconstruct the correct carbonate-platform model sensu Read (1985). ...
... The abrupt influx of CRA (facies associations TD) over all the MICP (Figs. 7, 12 d and 14) coincides with the decline of coral reef builders during the Chattian (Kiessling and Golonka 2003;Gatt and Gluyas 2012;Pomar et al. 2017). No evidence of buildups is seen in seismic along the edge of sigmoidal strata (Fig. 6 b) which left the inner-platform environment increasingly exposed to hydrodynamically mobile sediments of the platform margin composed of calcite-dominated CRA, LBF and bryozoans that have a low diagenetic potential (Isern et al. 2005). ...
The < 900-m-thick Paleogene carbonates of the Maltese Islands and offshore wells comprise 16 facies grouped into 7 carbon-ate facies associations (TA, TB, TC, TD1, TD2, TE1 and TE2). Previous works misclassified facies as belonging to a carbon-ate ramp, which derailed hydrocarbon exploration. This study confirms that the 200-km-wide, flat-topped, Malta isolated carbonate platform consists of coarse-grained, platform margin sediments surrounding the muddy, shallow marine interior that was tectonically segmented by half graben during foreland extension. Dating by correlation to benthic foraminiferal zones reveals two > 15Ma-long depositional hiatuses that bound the Eocene carbonates. Cyclic sediments are capped by Eocene gypsum beds and Oligocene palaeosolsand were controlled by third-order sea level cycles. About 700m of inner platform sediments accumulated from the Eocene (TA and TB) to the early Chattian (TC) until an abrupt and ubiquitous change to platform margin facies dominated by coralline red algae and subordinate corals (TD1). The succeeding transgres-sive rhodalgal biostrome (TD2) aggraded > 40m and prograded into underfilled half graben, later capped by mobile dunes of large benthic foraminifera (TE1). Deeper water oligophotic to aphotic biota (TE2) draped over the platform by the late Chattian. Increased foreland subsidence and the spread of coarse-grained platform margin sediments signals the beginning of the drowning succession reflecting environmental stress, the decline of coral reef builders, reduced sedimentation rate and increased dispersal rates, culminating in hardgrounds along the drowning surface that terminated carbonate platform sedimentation by the end of the Chattian.
... The carbonate platforms constitute the main component of the carbonate-deposition system that extends from the area below the tidal zone to the lower edge of the carbonate shelf. Spatial relationships of carbonate platforms mainly refer to the depth of the photic zone and potential of the carbonate factory production (e.g., [3,4]). ...
... Carbonate platforms are represented by specific deposits, related to well-defined sedimentary environments. Their development and diversity reflects a spectrum of variability of individual environmental factors, therefore their analyses have a fundamental importance for the reconstruction of former marine environments, as well as for recognizing their palaeobiology and evolution (e.g., [2][3][4][5][6]). Fragmented deposits of shallow-water platforms removed to deep sea environments and preserved within turbidites and olistostromes constitute the only material available for such analyses. ...
The present work focuses on palaeogeographic reconstruction of shallow-water carbonate deposition in the Outer Western Carpathian Tethys. Platform deposits are preserved only as a component of turbidites and olistostromes, and reconstructions of these platforms are based on clastic material redistributed into slopes and deep basins and occurring among the Outer Carpathian nappes. Similar platforms were also present on the Tethys margins. These reconstructions were performed using the global models of plate tectonics. Several ridges covered by carbonate platforms developed in that area during the latest Jurassic-Palaeogene times. Three main shallow-water facies associations-Štramberk, Urgonian, and Lithothamnion-bryozoan-could be distinguished. The Ti-thonian-lowermost Cretaceous Štramberk facies is related to early, synrift-postrift stage of the development of the Silesian Domain. Facies that are diversified, narrow, shallow-water platforms, rich in corals, sponges, green algae, echinoderms, foraminifera, microencrusters, and microbes are typical of this stage. The Urgonian facies developed mainly on the south margin of the Outer Carpa-thian basins and is characterised by organodetritic limestones built of bivalves (including rudists), larger benthic foraminifera, crinoids, echinoids, and corals. Since the Paleocene, in all the Western Outer Carpathian sedimentary areas, Lithothamnion-bryozoan facies developed and adapted to unstable conditions. Algae-bryozoan covers originating on the siliciclastic substrate are typical of these facies. This type of deposition was preserved practically until the final stage in the evolution of the Outer Carpathian basins.
... As suggested by Luan et al., (2017), a significant drowning event on the Yangtze region occurred during the late Floian, attributed to a eustatic sea-level rise (Liu, 2006;Haq and Schutter, 2008). It not only expanded ranges of the epeiric sea and enhanced the formation of carbonate platforms globally (Kiessling et al., 2003), but also resulted in the depositional transition from shelf to ramp in South China. A reduced rate of sedimentation characterized this event, but was heterogeneously recorded at the different studied sections (Figs. 10 and 11). ...
A robust stratigraphic framework and a coherent depositional ramp model for the Zitai, Dawan, Meitan and Ningkuo formations of Floian–Darriwilian age (Early–Middle Ordovician) in the Yangtze (Daoba, Xiangshuidong, Daling, Gudongkou and Honghuayuan sections) and Jiangnan regions (Nanba section) was created based on lithofacies and major element analysis. Three siliciclastic (LF1–3) and six carbonate (LF4–9) lithofacies are recognized representing sediments that were deposited in mixed siliciclastic and carbonate ramp environment. The intensity of mixed sedimentation and terrigenous input were evaluated using the elemental proxies Intensity of Mixed sedimentation (IM) and Aluminum Accumulation Rate (AlAR), as well as their mean values during certain time intervals. Mixed sediments are most well‐developed along the marginal Yangtze region, strongly impacted by recurrent influx of westerly derived terrigenous materials in response to global eustatic changes and regional tectonic movements, shaping the gently southeast‐dipping morphology. Regular terrigenous influx resulted in periods of enhanced primary productivity on the Yangtze Ramp as evidenced by matching biodiversity peaks in planktonic organisms, i.e., chitinozoans and acritarchs. Brachiopods and other shelly fauna were also able to proliferate as new niches developed along the gently dipping ramp floor with substrate changes. The biodiversification patterns suggest that terrigenous influx controlled in part by regional tectonics played a more important role than previously thought in the development of Great Ordovician Biodiversification Event in South China.
... 该时期海洋碳同位素出现负偏(图4(a)), 原有 图 4 (网络版彩色)二叠纪-三叠纪之交碳同位素与生物标志物指标的变化 [57] . [90,91] . 由于陆源 输入增加导致的海水富营养化, 促进了蓝细菌在浅海 爆发, 并成为最主要的初级生产者 [75] , 这一过程加剧了 水体缺氧和海水分层 [92,93] . ...
The evolution of deep-time marine biological pumps (BPs) is critical to our understanding of the processes and mechanisms
of the present-day carbon cycle. The Late Paleozoic-Early Mesozoic was a key period for the formation of modern marine
biological pumps. Two types of Phanerozoic biological pump have been recognized: Paleozoic (Paleozoic-Middle Triassic)
and Modern (Late Triassic-Modern). The Paleozoic-type pump comprises benthic algae and acritarch, whereas the Moderntype pump consists mainly of pelagic plankton. Geological records show that the Permian-Triassic extinction event destroyed
the Paleozoic BP. Then, a special BP composed of cyanobacteria and other autotrophic bacteria, briefly appeared during the
Permian-Triassic extinction interval. The Modern-type BP consists primarily of pelagic nannoplankton that originated in the
Late Triassic. Fossil records suggest that the origin and rapid radiation of nannoplankton (coccoliths and dinoflagellates)
during the Late Triassic to Early Jurassic promoted the establishment of modern plankton ecosystem. The rise of pelagic
plankton such as dinoflagellates, coccolithophores, and planktonic foraminifers in the Mesozoic is summed up as the
Mesozoic plankton revolution. The Mesozoic plankton revolution changed the patterns of marine material cycling and energy
flow. The proliferation of nannoplankton accelerated the transfer of material and energy from primary producers to larger
consumers and higher trophic levels, increasing the resources available to mesotrophic levels of marine ecosystems. The
increased availability of energy resulted in rapid changes in composition, spatial structure, and food chain structures of marine
fauna. The resulting “biological arms race” is summarized as the Mesozoic marine animal revolution. The Mesozoic plankton
revolution was also the key driver of the Mid-Mesozoic revolution in terms of the regulation of ocean chemistry. Before the
Early Jurassic, fluctuations in sea level, ocean area, continental weathering rates, and oceanic calcium ion concentrations
produced large perturbations in carbonate deposition and the oceanic carbon cycle, which were only weakly buffered by the
ocean. After the Early Jurassic, seawater chemistry changed—With the decrease and stabilization of carbonate saturation due
to the transfer of biogenic carbonate from the shallow to the deep marine deposits—Mainly as a result of the rise of
nannoplankton and tectonic movement. Changes in seawater chemistry are also reflected in the increased oxygen
concentration therein. The oxygen concentration was higher on the Jurassic shelf, likely due to pelagic planktonic algal
blooms. The occurrence of phytoplankton increased the efficiency of pelagic biological and carbonate pumps, and the
accumulation and dissolution of deep-sea carbonates began to emerge as an important link in the carbon cycle; this improved
the buffering capacity of ocean against environmental disturbances. It also provided a stable environment for the creation of
modern marine ecosystem, and several oceanic anoxic events that occurred in the Mesozoic did not directly lead to mass
extinctions of marine animals, causing only small fluctuations in the diversity of some taxa. Therefore, the Mesozoic plankton
revolution is a critical link between the animal and chemical revolutions, and these three processes make up the Mesozoic
marine revolution. The origin and evolution of key marine producers and their controlling factors are important topics that
need to be studied. However, there are few high-precision studies on the evolution of primary producers and biological pumps
during the Late Paleozoic-Early Mesozoic. In addition, the timeline and mechanisms driving the origin of pelagic
phytoplankton are key questions that need to be addressed. To solve these problems, the evolution of photosynthetic pigment
lineages and the paleogeographic distribution of algae, along with the changes in the size of plankton during the early
Mesozoic, require further research attention.
... Rift basins with partially or completely isolated blocks were formed on which shallow-marine carbonate deposition persisted ('fault-block platforms' of Bosence 2005). In the late Early Cretaceous, the largest and most widespread platforms of the entire Mesozoic developed in tropical and subtropical seas from accumulations of shallow-water carbonates rich in rudists, corals, chaetetids and stromatoporoids (Simo et al. 1993;Michalik 1994;Kiessling et al. 2003;Philip et al. 1995;Philip 2003). ...
... The concept of time-specific facies (Walliser, 1984(Walliser, , 1996 denotes distinctive facies restricted to a precise time slice when they occur in more than one locality globally, while being totally absent in other intervals of the geologic time Brett et al., 2012). The Devonian Period was a time of the broadest geographic expanse of carbonate platforms for the Paleozoic (Kiessling et al., 2003), with reef tracts likely reaching high latitudes of about 45 • S to 45 • N (Copper and Scotese, 2003;Joachimski et al., 2009). These reefs s.l. ...
This paper reviews global records of anoxic events of the Middle Devonian – earliest Mississippian, as well as the possible triggers and controls of these events. These “anoxic events” are complex multistage paleoenvironmental disturbances manifested in multiple proxies, which we showcase with the Horn River Group (HRG) – a succession of basinal organic-rich shales and cherts deposited during the latest Eifelian – earliest Late Frasnian (∼386–373 My ago) on the western continental margin of Laurentia near the paleo-equator. Four major events imprinted in the HRG are the Kačák, Frasnes, basal punctata, and late punctata events, but positive δ13C excursions (measured on organic matter) are more numerous and can potentially be matched to other global events. The Kačák event in the base of the HRG manifests as a regional switch from carbonate-platform to anoxic sedimentation. Three major events of the latest Givetian – Middle Frasnian display repeating sequences characterized by: (1) an early shift to heavier δ13C values coupled with siliciclastic enrichment and mercury enrichment spikes of up to 0.48 ppm; (2) late-stage δ13C reversal to background values coincident with the onset of severe anoxia (buildup of authigenic U, Mo, V) and attenuation of siliciclastic supply. Devonian anoxic sediments, including HRG, display widespread presence of chlorobi biomarkers, which indicates episodes of photic-zone euxinia in the water column. Most of these sediments were deposited under open ocean conditions, precluding a Black Sea water-column stratification scenario. These observations indicate Devonian anoxic events are similar to classical Mesozoic oceanic anoxic events (OAEs), consistently with growing evidence for a volcanic trigger for these events (e.g. spikes in Hg and negative 187Os/188Os anomalies). Oxygen minimum zones in a greenhouse ocean, such as the one recorded in basinal HRG, were prone to expansion under volcanic CO2 reinforcement. This volcanic press-pulse also intensified the hydrological cycle, which resulted in a boost of weathering and eutrophication of shelfal seas. These factors, amplified by deoxygenation and acidification of the habitable upper ocean, drove extinctions of various magnitude. As a proxy for the input of land-plant detritus, the oxygen index from pyrolysis data shows zero response to anoxic events in the HRG, which aligns with broader evidence that counters expanding vascular vegetation to be the driver of the marine biotic crises. Finally, our review highlights how controversial the evidence of high-frequency (3rd to 5th orders) sea-level fluctuations is in the Devonian. In particular, none of the geochemical proxies usually employed to interpret sea-level changes translates unequivocally into transgressions and regressions in the greenhouse world. This sea-level puzzle clearly calls for new scrutiny and justifies scepticism in the validity of the classical “eustatic sea-level curve of the Devonian”, as well as estimates of eustatic amplitudes in excess of ∼25 m for 3rd and 4th order cycles.
... Rift basins with partially or completely isolated blocks were formed on which shallow-marine carbonate deposition persisted ('fault-block platforms' of Bosence 2005). In the late Early Cretaceous, the largest and most widespread platforms of the entire Mesozoic developed in tropical and subtropical seas from accumulations of shallow-water carbonates rich in rudists, corals, chaetetids and stromatoporoids (Simo et al. 1993;Michalik 1994;Kiessling et al. 2003;Philip et al. 1995;Philip 2003). ...
The Middle Member of the Llopis Fm in the Sierra de Bedmar-Jódar Unit of the Prebetic Zone of Jaén (southern Spain) was deposited on a shallow-marine platform of the Southern Iberian Continental Margin during the earliest Aptian. Detailed field logging of nine stratigraphic sections and facies mapping have allowed seven lithofacies associations (L1–L6) to be distinguished, one siliciclastic (L1) and five carbonate facies (L2–6). The succession is composed of eight consecutive elemental sequences of lithofacies associations L1–L6. Each elemental sequence is interpreted as representing one episode of shallowing-upwards carbonate deposition in a very shallow platform-lagoon that was bounded shoreward by clastic/ooid bars and passed seaward either to stromatoporoid bioconstructions (bioherms and biostromes) or rudist biostromes. The successive elemental sequences show north-eastward progradational geometries. Three phases of platform development are identified: (1) installation of the shallow platform; (2) development of a lagoon bounded by a stromatoporoid barrier and (3) development of an Urgonian-type platform dominated by rudists. During the early Aptian, the Bedmar-Jódar platform was partially isolated from the rest of the Prebetic platform and showed overall progradation towards the NE, in contrast to the general south-eastward progradational trend of the Prebetic platform. Sedimentation was controlled by rift-generated extensional tectonics that resulted in tilting of the platform block, causing the deviation of progradation from the general trends of the Prebetic Platform. In addition, climatic influence is inferred from the presence of siliciclastic sediments derived from weathering of the hinterland, which restricted the carbonate factory.
... The continent was oriented ~90° clockwise in comparison with its present orientation (Rowland and Shapiro, 2002;Torsvik and Cocks, 2017). Seaward of the craton-margin region where the FMD was being deposited was the "Great American Carbonate Bank" Taylor et al., 2012), the most extensive carbonate platform accumulation on Earth at that time (Kiessling et al., 2003). ...
We describe, interpret, and establish a stratotype for the Frenchman Mountain Dolostone (FMD), a new Cambrian stratigraphic unit that records key global geochemical and climate signals and is well exposed throughout the Grand Canyon and central Basin and Range, USA. This flat-topped carbonate platform deposit is the uppermost unit of the Tonto Group, replacing the informally named “undifferentiated dolomites.” The unit records two global chemostratigraphic events—the Drumian Carbon Isotope Excursion (DICE), when δ13Ccarb (refers to “marine carbonate rocks”) values in the FMD dropped to −2.7‰, and the Steptoean Positive Carbon Isotope Excursion (SPICE), when the values rose to +3.5‰. The formation consists of eight lithofacies deposited in shallow subtidal to peritidal paleoenvironments. At its stratotype at Frenchman Mountain, Nevada, the FMD is 371 m thick. Integration of regional trilobite biostratigraphy and geochronology with new stratigraphy and sedimentology of the FMD, together with new δ13Ccarb chemostratigraphy for the entire Cambrian succession at Frenchman Mountain, illustrates that the FMD spans ~7.2 m.y., from Miaolingian (lower Drumian, Bolaspidella Zone) to Furongian (Paibian, Dicanthopyge Zone) time. To the west, the unit correlates with most of the Banded Mountain Member of the ~1100-m-thick Bonanza King Formation. To the east, at Grand Canyon’s Palisades of the Desert, the FMD thins to 8 m due to pre–Middle Devonian erosion that cut progressively deeper cratonward. Portions of the FMD display visually striking, meter-scale couplets of alternating dark- and light-colored peritidal facies, while other portions consist of thick intervals of a single peritidal or shallow subtidal facies. Statistical analysis of the succession of strata in the stratotype section, involving Markov order and runs order analyses, yields no evidence of cyclicity or other forms of order. Autocyclic processes provide the simplest mechanism to have generated the succession of facies observed in the FMD.
... In the Mediterranean Sea, the endemic species Cladocora caespitosa builds large bioconstructions in the shallow waters of coastal bays and other protected marine environments [3][4][5][6][7][8]. Symbiont-bearing colonial corals have been prominent carbonateproducing organisms since the Paleozoic, building extensive reefs in the Devonian, Late Triassic, Middle and Late Jurassic, and from the Oligocene onward [9][10][11]. Mainly shells of gastropod Palaeozygopleura hamiltoniae occupied by a secondary inhabitant, but also other molluscs and brachiopods [20] Bohemia (Czech Republic) Devonian Hyostragulum (tabulate coral) ...
In order to investigate the serendipitous find of a gastropod encrusted by the symbiont-bearing colonial coral Oculina patagonica, we examined several specimens of cnidarian-encrusted gastropods, ranging in age from the Pliocene to the Recent, and characterized in detail their sclerobiont cover. The results of our analysis suggest that gastropod shells can be encrusted by symbiont-bearing colonial corals at various times: (1) when the gastropod is alive; (2) when the shell is being used by a secondary inhabitant (e.g., hermit crabs or sipunculid worms); (3) when the shell is discarded but yet to be buried. The relationship between the symbiont-bearing coral and the inhabitant(s) of the encrusted shell is an example of facultative mutualism, i.e., it is non-obligate yet beneficial for both ends as the former obtains the capability to move, and the latter improves the resistance and resilience of its armor, thus obtaining extra protection from predators. Being able to move could prove particularly useful for a symbiont-bearing coral because, in addition to removing the risk of being smothered by sediment, it would also favor the photosynthetic activity of its algal endosymbionts by allowing the coral to be always clean of sedimentary particles. Although the resulting epibiotic association would be limited in size by the ability of either the gastropod or the secondary inhabitant of the shell to move at the seafloor, these small and easy-to-miss benthic islands might become the seeds that allow sessile carbonate producers such as hermatypic colonial corals to colonize unconsolidated substrates.
... The concept of time-specific facies (Walliser, 1984(Walliser, , 1996 denotes distinctive facies restricted to a precise time slice when they occur in more than one locality globally, while being totally absent in other intervals of the geologic time Brett et al., 2012). The Devonian Period was a time of the broadest geographic expanse of carbonate platforms for the Paleozoic (Kiessling et al., 2003), with reef tracts likely reaching high latitudes of about 45 • S to 45 • N (Copper and Scotese, 2003;Joachimski et al., 2009). These reefs s.l. ...
... Study of larger benthic foraminifera yields vital evidences for paleoenvironmental settings. Kiessling et al. (2003) mentioned that suitable paleogeography with warm climate resulted in increase of carbonate production in temperate areas lying at more than 45°N latitude with LBF and algae as the major sediment contributors. Nummulites are considered as rock-forming fauna and accumulate in typical banks, sometimes related to paleoreliefs. ...
The present study deals with microfacies analysis, paleoecology and sequence stratigraphy of the Lower–Middle Eocene rocks in central Nile Valley and west-central Sinai. Four rock units were marked (Minia, Darat, Samalut and Maghagha formations). Eight facies belts were interpreted including lagoon, back bank, main bank, fore bank and open marine outer bank facies and deposited on a gently dipping platform ramp. This ramp might be further divided to three main faunal associations depending on the depth of the water and associated fauna. Four major depositional sequences (DS1–DS4), reflecting third-order cycles and separated by two prominent sequence boundaries (SB1 and SB2) were marked. The record of these sequences reflects the changes in eustatic sea level plus the regional tectonism in the area. Every sequence includes facies associations, which constitute lowstand and/or transgressive and highstand systems tracts. Based on faunal elements and facies analysis, the water salinity, water temperature, nutrients, substrate, water depth and hydrodynamic behavior were discussed. The fine-grain size of the deposits, the loss of good connectedness and the occluding of the Nummulite tests by other minerals could give rise to low reservoir potential. The sedimentation was affected by the tectonic activity of the Syrian orogeny. Moreover, both external and internal mechanisms have controlled the carbonate sedimentation, basin construction and sequence bounding surfaces.
... Fig. 10 shows the global changes in temperature and sea level, particularly within the southern Baltica shelf during the Silurian-Early Devonian. The surface seawater temperature in the Silurian exceeded 20 °C [Verniers et al, 2008], and in the Lochkovian time of the Early Devonian exceeded 30 °C [Kiessling, 2002, Kiessling et al, 2003. Such climatic conditions contributed to the intensive carbonate accumulation in the shelf sediments of the studied basin (Fig. 9). ...
Purpose. The objective of this study is the investigation of the Silurian-Lower Devonian (Lochkovian) carbonate-clay sedimentary complex of the southwestern slope of the East-European platform. Its formation was the result of a single cycle of geodynamic and sedimentary events in the lithological record of the southern continental margin of Baltica. Methodology. The study is based on well-logs correlation, lithological and geochemical investigations of core samples, and petrographic thin sections analysis. The obtained results were used to establish patterns of changes in the material composition of the studied strata in time and space in order to determine the basin development dynamics of the continental margin of the Eastern European platform southwestern slope in the Silurian-Early Devonian. Results. It is established that the formation of the carbonate-clay sequence represents a single sedimentary cycle and was the result of a complex of geodynamic, depositional and paleoclimatic events that took place on the Baltica southern continental margin. The Silurian period was characterized by intensive development of benthic organisms and reef structure formation in the proximal part of the basin and clay-carbonate muds enriched with dispersed organic matter in its distal part. In the Early Devonian, carbonate biogenic sedimentation continued throughout the basin. The carbonate maximum content (80–98%) proves the existence of the reef constructions in the basin sedimentary record. Lower values of carbonate content are characteristic of marls (40–55%) and biodetritic limestones (56–75%), which make up the main part of the Silurian sequence. There are no reef constructions in the section of the Lochkovian stage of Devonian, and the calcium carbonate content in the rocks varies from 45 to 83%. The content of CaCO3 in mudstones and calcareous mudstones of the Silurian varies from 5 to 15%. Originality. The applied complex of lithological, geochemical, geological-geophysical and paleogeographic investigations allowed studying the sedimentary basin dynamics in the Silurian-Early Devonian with the assessment of the possibility of participation of these strata in oil and gas hydrocarbons generation. Practical significance. The obtained results show that the carbonate-clay complex of sedimentary rocks of the Silurian and Lower Devonian (Lochkovian) of the studied region can be considered as a separate petroleum system, including source rocks, reservoir rocks and possible conventional and unconventional oil and gas accumulations.
... Life flourished in the oceans, and marine faunas attained their highest genuslevel richness for the entire Paleozoic in the Givetian-Frasnian (e.g., Bambach et al., 2002). At the same time, reefs with a high diversity of metazoan organisms reached their peak abundance for the Paleozoic (Kiessling et al., 2003). Devonian paleogeography comprised three major continents. ...
The Devonian has long been a problematic period for paleomagnetism. Devonian paleomagnetic data are generally difficult to interpret and have complex partial or full overprints– problems that arise in data obtained from both sedimentary and igneous rocks. As a result, the reconstruction of tectonic plate motions, largely performed using apparent polar wander paths, has large uncertainty. Similarly, the Devonian geomagnetic polarity time scale is very poorly constrained. Paleointensity studies from volcanic units suggest that the field was much weaker than the modern field, and it has been hypothesised that this was accompanied by many polarity reversals (a hyperreversing field). We sampled Middle to Upper Devonian sections in Germany, Poland and Canada which show low conodont alteration indices, implying low thermal maturity. We show that there are significant issues with these data, which are not straightforward to interpret, even though no significant heating or remineralisation appears to have caused overprinting. We compare our data to other magnetostratigraphic studies from the Devonian and review the polarity pattern as presented in the Geologic Time Scale. Combined with estimates for the strength of the magnetic field, we suggest that the field during the Devonian might have been so weak, and in part non-dipolar, that obtaining reliable primary paleomagnetic data from Devonian rocks is challenging. Careful examination of all data, no matter how unusual, is the best way to push forward our understanding of the Devonian magnetic field. Paleointensity studies show that the field during the Devonian had a similar low strength to the Ediacaran. Independent evidence from malformed spores around the Devonian-Carboniferous boundary suggests that the terrestrial extinction connected to the Hangenberg event was caused by increased UV-B radiation, supporting the weak field hypothesis. A fundamentally weak and possibly non-dipolar field during the Devonian could have been produced, in part, by true polar wander acting to maximise core-mantle heat flow in the equatorial region. It may also have influenced evolution and extinctions in this time period. There are a large number of paleobiological crises in the Devonian, and we pose the question, did the Earth’s magnetic field influence these crises?
... 该时期海洋碳同位素出现负偏(图4(a)), 原有 图 4 (网络版彩色)二叠纪-三叠纪之交碳同位素与生物标志物指标的变化 [57] . [90,91] . 由于陆源 输入增加导致的海水富营养化, 促进了蓝细菌在浅海 爆发, 并成为最主要的初级生产者 [75] , 这一过程加剧了 水体缺氧和海水分层 [92,93] . ...
The evolution of deep-time marine biological pumps (BPs) is critical to our understanding of the processes and mechanisms of the present-day carbon cycle. The Late Paleozoic-Early Mesozoic was a key period for the formation of modern marine biological pumps. Two types of Phanerozoic biological pump have been recognized: Paleozoic (Paleozoic-Middle Triassic) and Modern (Late Triassic-Modern). The Paleozoic-type pump comprises benthic algae and acritarch, whereas the Modern-type pump consists mainly of pelagic plankton. Geological records show that the Permian-Triassic extinction event destroyed the Paleozoic BP. Then, a special BP composed of cyanobacteria and other autotrophic bacteria, briefly appeared during the Permian-Triassic extinction interval. The Modern-type BP consists primarily of pelagic nannoplankton that originated in the Late Triassic. Fossil records suggest that the origin and rapid radiation of nannoplankton (coccoliths and dinoflagellates) during the Late Triassic to Early Jurassic promoted the establishment of modern plankton ecosystem. The rise of pelagic plankton such as dinoflagellates, coccolithophores, and planktonic foraminifers in the Mesozoic is summed up as the Mesozoic Plankton Revolution. The Mesozoic Plankton Revolution changed the patterns of marine material cycling and energy flow. The proliferation of nannoplankton accelerated the transfer of material and energy from primary producers to larger consumers and higher trophic levels, increasing the resources available to mesotrophic levels of marine ecosystems. The increased availability of energy resulted in rapid changes in composition, spatial structure, and food chain structures of marine fauna. The resulting “biological arms race” is summarized as the Mesozoic Marine Animal Revolution. The Mesozoic Plankton Revolution was also the key driver of the Mid Mesozoic Revolution in terms of the regulation of ocean chemistry. Before the Early Jurassic, fluctuations in sea level, ocean area, continental weathering rates, and oceanic calcium ion concentrations produced large perturbations in carbonate deposition and the oceanic carbon cycle, which were only weakly buffered by the ocean. After the Early Jurassic, seawater chemistry changed—With the decrease and stabilization of carbonate saturation due to the transfer of biogenic carbonate from the shallow to the deep marine deposits—Mainly as a result of the rise of nannoplankton and tectonic movement. Changes in seawater chemistry are also reflected in the increased oxygen concentration therein. The oxygen concentration was higher on the Jurassic shelf, likely due to pelagic planktonic algal blooms. The occurrence of phytoplankton increased the efficiency of pelagic biological and carbonate pumps, and the accumulation and dissolution of deep-sea carbonates began to emerge as an important link in the carbon cycle; this improved the buffering capacity of ocean against environmental disturbances. It also provided a stable environment for the creation of modern marine ecosystem, and several oceanic anoxic events that occurred in the Mesozoic did not directly lead to mass extinctions of marine animals, causing only small fluctuations in the diversity of some taxa. Therefore, the Mesozoic Plankton Revolution is a critical link between the animal and chemical revolutions, and these three processes make up the Mesozoic Marine Revolution. The origin and evolution of key marine producers and their controlling factors are important topics that need to be studied. However, there are few high-precision studies on the evolution of primary producers and biological pumps during the Late Paleozoic-Early Mesozoic. In addition, the timeline and mechanisms driving the origin of pelagic phytoplankton are key questions that need to be addressed. To solve these problems, the evolution of photosynthetic pigment lineages and the paleogeographic distribution of algae, along with the changes in the size of plankton during the early Mesozoic, require further research attention.
... The Devonian Period had expansive reefs that contributed to abundant carbonate production and the greatest marine diversity of the Paleozoic Era, including the appearance and diversification of aquatic tetrapods (e.g., Becker et al., 2020;Bambach et al., 2002;Kiessling et al., 2003). The Late Devonian time-period in particular saw significant changes in global climate, sea level, and marine geochemical records (Hillbun et al., 2015. ...
Late Devonian time was a period of rapid upheaval in the Earth system, including climate change, sea level changes, widespread ocean anoxia, and the Frasnian-Famennian mass extinction; the cause(s) of these changes remain(s) uncertain. The Lennard Shelf of the Canning Basin in Western Australia contains carbonate reef sections spanning much of the Late Devonian Epoch and has been sampled for paleomagnetic analysis with studies by Hansma and colleagues in 2015 and Playton and colleagues in 2016. However, previous paleomagnetic directions were scattered and their use for magnetostratigraphy has been questioned. Here, rock magnetic data and magnetostratigraphy for a late Devonian drill-core from the Lennard Shelf were analyzed. Three magnetostratigraphic interpretations were made using different paleopoles that showed good correlation with each other and the earlier interpretations by Playton and colleagues in 2016. Additionally, the rock magnetic data revealed the samples contain various mixtures of detrital and diagenetic minerals, the former of which should be viable recorders of primary magnetic signatures. Even in samples with these detrital phases, paleomagnetic data were often noisy and produced ambiguous polarity assignments, likely due to the anomalously weak Devonian field. Because of this ambiguity and the absence of a robust paleopole, broader correlations for this critical time-period will be difficult without additional paleomagnetic data from the late Devonian Period. Expanded data for this interval could eventually shed light on the timing, causes, and rates of the Frasnian-Famennian mass extinction and other environmental shifts in the late Devonian Epoch.
... Ecological factors such as the origin and expansion of organic reefs, hardground communities, bryozoan thickets, and crinoid gardens during the Ordovician (Sepkoski 1988) must be invoked. Such ecosystem change is generally related to increased temperate that may itself enable biodiversity (Mayhew et al. 2012) and promote the development of carbonate platforms, mounds and reefs that provide a multiplicity of niches and opportunities for organisms (Kiessling et al. 2003). ...
Diversification is a key property of life. Building on John Phillips' (1860) classic, iconic curve, Phanerozoic biodiversity trajectories have been based, subsequently, on the availability of additional and renewed sets of data and increasingly sophisticated analytical methods. Using relatively few single sources of data from global databases, the shapes of recent biodiversity curves for Ordovician biotas have predictably converged promoting acceptance of discrete events, aligned with relatively few peaks and discrete drivers. There has been a resistance to investigate under the curves and examine the many and varied causes of biodiversity. Most of the data available pertains to the most abundant part of the benthos, the brachiopods, and more especially their occurrences in Baltica and Laurentia together with South China. Exploration of several regional datasets, deconstructed from global curves, for some key fossil groups indicates the regions that do have their own distinctive biodiversity signals, usually associated with low-latitude settings, but also highlights significant gaps in our knowledge.
... Carbonate platform sediment production is sensitive to water depth, temperature, terrigenous inputs, CO 2 concentration, and sea water chemistry, as well as biological evolution (Schlager, 1981;Hallock and Schlager, 1986;James, 1997;Kiessling et al., 2003;Bosence, 2005;Lokier et al., 2009;Stanley et al., 2010;Betzler et al., 2013;Liu et al., 2014;Brandano and Ronca, 2014;Brandano et al., 2015;Corda and Palmiotto, 2015;Fontana et al., 2015;Coletti et al., 2017;Pomar et al., 2017;Michel et al., 2018). Various carbonate-producing biota tend to flourish in different environments. ...
Sedimentological, paleontological, and geochemical data from core XK-1 on the Xisha Islands have allowed for a detailed documentation of the early carbonate development around the Oligocene-Miocene transition in the northern South China Sea (SCS). The deposits within the fore reef, reef, lagoon environments occurred before 23 Ma, the exposure horizon occurred around 23 Ma, and the sediments within the open lagoon setting dominated after 23 Ma. This evolution indicates a sedimentological response to water depth change, which is the combined result of eustatic sea-level fluctuations and tectonic subsidence. The tectonic subsidence during the latest Oligocene and Early Miocene (especially this period) was responsible for the obvious deepening trend. What's more, substantial physical erosion caused an increased amount of terrigenous input into the Xisha Islands area, with detrimental effects on carbonate development after the Oligocene-Miocene boundary. Over the entire South China Sea, the early carbonate systems along the northern and southern margins displayed specific evolution patterns. After comparing these patterns, we found a close relationship between the carbonate initiation and the subduction of the proto-SCS and the opening of the modern SCS. Therefore, it has been demonstrated that sea level and local tectonics as well as paleoclimatic conditions were the main controlling factors in shaping the onset of carbonate sedimentation in the SCS.
... The vast amount of marine organic matter buried in geographically extensive Late Ordovician-Early Silurian anoxic sediments (Melchin et al., 2013) is reasonably held accountable for the CO 2 drawdown during the sub-phase 2α (Fig. 13F). Another pathway leading to extensive sink of atmospheric carbon is the intensified silicate weathering linked in some works to the Middle-Late Ordovician Taconic Orogeny (Kump et al., 1999;Young et al., 2010) and the teamed process of bounding carbon with the released inventory of Ca 2+ and Mg 2+ in carbonate platforms which greatly expanded during that time (Kiessling et al., 2003). The waning inventory of CO 2 available to form carbonic acid, the major agent in silicate weathering (Berner, 2006;Penman et al., 2020), offers an explanation for Late Ordovician-Early Devonian slowdown in the weathering intensity as expressed in ω trend (Lipp et al., 2021). ...
Dozens of subaerial exposure surfaces are assessed in cores from cyclic peritidal carbonates of the Emsian–Eifelian (~410-385 Ma) age. These surfaces range from incipient erosional surfaces to paleokarst profiles and thick (>1m) calcretic-clayey paleosols. Palustrine carbonates intervening at multiple levels in same strata are the earliest known occurrence of a typical palustrine facies in a coastal carbonate plain environment. None of paleokarst and paleosol profiles contain traces of vascular-plant root penetration, and only palustrine facies exhibit swarms of thin rhizoliths. These findings are within the context of Devonian paleosols on marine carbonate substrates where root traces and laminar calcretes are extremely rare (only 2 reports), and no instances of root penetrations are trackable from unconformities in pre-Givetian carbonate successions. The δ13C and δ18O signatures indicate variable diagenetic reset of isotopic composition. Modest δ13Cvpdb offset towards lighter values is preserved in two thicker paleosols (-3.4 to -8.0‰ in calcretic matrix vs. -1.35 to -6.5‰ in parent limestone). Such offsets are very rare in pre-Late Devonian pedogenic carbonates, and their attribution to plant-derived CO2 is dubious. It is inferred that the land surface in calcimagnesian landscapes remained a regolith or primary desert (i.e., was never colonized by tracheophytes) long after the spread of vascular plants in more favorable wetland settings. Furthermore, the advent of seed reproductive strategy in the latest Devonian and plant adaptations to aridic habitats manifesting in fossil floras only since Pennsylvanian indicate that much of land surface remained within the realm of primary desert long after the afforestation of wetlands. The direct (plant roots, shoots and spores) and indirect (sedimentary features) fossil records of land greening during the Paleozoic are not corroborating the hypothesis holding the primordial embryophytic cover on land accountable for the Late Ordovician atmospheric oxygenation-decarbonization event. It is further argued that the evolution of root systems and plant stature could hardly trigger anoxic events and biotic crises in the Devonian marine realm.
... The GOBE had multiple global environmental drivers that were mediated by regional-scale processes, including carbonate platform development, biotic invasions, and latitudinal shifts due to tectonic movements (e.g., Kiessling et al. 2003;Servais and Harper 2018;Stigall 2018). The impact of these regional processes on diversity is exemplified by the eastern Baltic paleobasin. ...
The Ordovician–Silurian (~485–419 Ma) was a time of considerable evolutionary upheaval, encompassing both great evolutionary diversification and one of the first major mass extinctions. The Ordovician diversification coincided with global climatic cooling and paleocontinental collision, the ecological impacts of which were mediated by region-specific processes including substrate changes, biotic invasions, and tectonic movements. From the Sandbian–Katian (~453 Ma) onward, an extensive carbonate shelf developed in the eastern Baltic paleobasin in response to a tectonic shift to tropical latitudes and an increase in the abundance of calcareous macroorganisms. We quantify the contributions of environmental differentiation and temporal turnover to regional diversity through the Ordovician and Silurian, using brachiopod occurrences from the more shallow-water facies belts of the eastern Baltic paleobasin, an epicontinental sea on the Baltica paleocontinent. The results are consistent with carbonate shelf development as a driver of Ordovician regional diversification, both by enhancing broadscale differentiation between shallow- and deep-marine environments and by generating heterogeneous carbonate environments that allowed increasing numbers of brachiopod genera to coexist. However, temporal turnover also contributed significantly to apparent regional diversity, particularly in the Middle–Late Ordovician.
... Bambach et al., 2002). At the same time, reefs with a high diversity of metazoan organisms reached their peak abundance for the Paleozoic (Kiessling et al., 2003). Devonian paleogeography comprised three major continents. ...
... The reduced thickness of early Oligocene carbonate cover ( Fig. 2: m 840 to 860) may have two main linked explanations: (1) A different water chemistry (Eocene-Oligocene transition: Pomerol and Premoli-Silva, 1986) avoiding good carbonate production, and thus not permitting accumulation of thick deposits. In that sense, Oligocene carbonate platforms are well-known as having lesser thicknesses than Eocene ones (Kiessling et al., 2003;Nebelsick et al., 2005); and (2) A relatively stable or falling sea level with export of most of the carbonate material to distal environments (Bolz and Calvo, 2018), thus avoiding thick accumulations in inner and middle ramp settings. The fall of relative sea level is supported by the development of a subaerial exposure surface topping the Rupelian carbonates (S2: Figs. 2, 4A-C). ...
Costa Rican Eocene–Oligocene carbonate deposits have been known for more than a hundred years, however, there are few scientific contributions detailing the relation between facies analysis and regional basin evolution. Based on a detailed study in southern Costa Rica, a chronologic history of a Bartonian–Aquitanian sedimentary succession is proposed. The carbonate facies analysis allows for eight microfacies (MF1 to MF8) to be distinguish. The siliciclastic facies analysis permits identification of two main periods of sandstone deposition and one of shale formation. The mixed sandstone/carbonate succession exhibits three main periods of deposition: (1) Bartonian–lower Priabonian, represented by distal, relatively deep slope-to-basin environments. Deposits comprise thick accumulation of sandstones, calcareous breccias, and calciturbidites. This period terminates with a stratigraphic erosion surface; (2) Upper Priabonian–Rupelian, represented by more proximal, shallow to mid depth inner to middle ramp environments. Deposits are composed of peloidal/cortoidal grainstone, foraminiferal-algal rudstones, and rhodolith rudstones. This period terminates with a second stratigraphic erosion surface; (3) Chattian–Aquitanian, represented by proximal to distal, shallow to coastal and offshore environments. Deposits are composed of a mixed siliciclastic‑carbonate thin complex overlain by dark shale.
The vertical and lateral facies changes permit a basin evolution model that is closely controlled by subsidence. Local tectonic uplift may have formed the first subaerial exposure surface. The second subaerial exposure surface may have been controlled by eustatic sea-level variations over relatively shallow water deposits. These results, the first-of-their-kind in the southern Costa Rican Fila Costeña, could permit improvements of lateral regional correlations by bringing new lithostratigraphic layers of reference.
... A Late Triassic acme of reefal biodiversity, area and carbonate production was terminated by the end-Triassic extinction and followed by an Early Jurassic reef gap (Flügel and Kiessling 2002). However, the global Phanerozoic history and productivity of carbonate platforms appear decoupled from that of the reefs, as platforms are generally less affected by biotic extinction (Kiessling et al. 2003). Indeed, many of the carbonate platforms survived elsewhere on the peri-Tethyan shelves into the Early Jurassic despite the reef crisis, including the Dinaric carbonate platform (Crne and Gorican, 2008), the Appenine platform (Mancinelli et al. 2005), the Gavrovo-Tripolitza platform (Pomoni-Papaioannou and Kostopoulou 2008) and the Pelagonian platform (Romano et al. 2008) in the Hellenides, and the Arabian platform in the equatorial Tethys (Ge et al. 2018). ...
The Dachstein platform was an extensive carbonate platform developed on the westernmost shelf of the Neotethys during the Late Triassic, now preserved in various tectonic units disrupted during the Alpine orogeny. Despite being the focus of a multitude of sedimentological, paleontological and other studies, the demise of this platform remains controversial, with contrasting views on the timing and causes of cessation of its growth, the duration of the gap above, which at many places includes the Triassic-Jurassic boundary (TJB), and the depositional environment of overlying strata.
Here we present new carbonate sedimentological, stable isotope and cyclostratigraphic data from sections in the Transdanubian Range (Hungary) which capture the termination of uppermost Triassic Dachstein Limestone and the onset of Hettangian (Early Jurassic) sedimentation following a hiatus. Previously, the TJB in the Transdanubian Range was regarded as a textbook case of a tectonically-driven platform drowning event or, alternatively, cessation of carbonate production due to emergence caused by a significant sea level fall at the TJB. However, recognition of global biotic change and environmental perturbations at the TJB calls for an assessment of their possible role in the demise of the Dachstein platform.
Oxygen and carbon isotopic composition of bulk carbonates were measured in sections at Kőris-hegy (Bakony Mts.), Tata (Tata Horst), and Vöröshíd (Gerecse Mts.) Paleogeographically, these three sections represent a proximal to distal platform transect. Other sections at Pisznice and Tölgyhát (Gerecse Mts.) yielded additional sedimentological data. The sharp surface separating the Dachstein Limestone from the overlying Jurassic formations carries no or only minimal relief at outcrop scale. Thin section studies reveal small-scale irregularities, stylolites, microborings with ferruginous filling, or a thin clay-rich layer at the TJB, indicative of a submarine, or perhaps polygenetic, hardground. In the first meters of the lowermost Jurassic beds abundant ooids occur, and crinoids become common. In each of the studied sections, an abrupt negative carbon isotope shift is recorded at the TJB, and a gradual rebound to more positive values characterizes the lowermost Jurassic strata. Chemostratigraphy allows correlation with sections elsewhere. In the Transdanubian Range, the initial carbon isotope excursion and at least the first part of the purported main carbon isotope excursion are not preserved due to the gap at the TJB. Combined bio- and cyclostratigraphy of lowermost Jurassic strata permits an astrochronologic duration estimate of the early Hettangian hiatus that was not longer than a few hundreds of thousand years.
Our results highlight the role of submarine erosion, perhaps partly related to acidification, and point to an abrupt change in carbonate production related to the end-Triassic extinction of several groups in the platform system. “Unreefing”, the ecological collapse of reefs, led to a regime shift, the transformation of the rimmed platform to a carbonate ramp, with a significant gap in production and preservation of carbonate sediment. This model is not uniformly applicable to Late Triassic platforms as several of them, unlike the Dachstein platform, survived with unrimmed architecture in the Early Jurassic elsewhere on the Neotethyan shelf. However, the model may explain features of the carbonate platform sedimentary record across other events with reef collapse.
... FA2 reflects a shallow carbonate platform deposited in the euphotic zone due to the presence of micrite, horizontal shape of beds and absence of large quantities of foraminifera and red algae which found in steepened ramps in the oligophotic framework (Pomar, 2001). The predominance of micrite, few contents of terrigenous grains and diversity of marine invertebrates suggest a shallow water environment (Tucker and Wright, 1990;Kiessling et al., 2003;da Silva, 2019). ...
The Tibasosa Formation is the main source of limestones in Boyacá. This unit corresponds to a Valanginian-Albian age according to the fossil content in the Eastern Cordillera Basin, recording the first incursion of the Cretaceous sea in Firavitoba. Outcrop-based facies and stratigraphic analyzes of the ~12 m-thick siliciclastic-carbonate succession of the uppermost Tibasosa Formation indicate tidal and carbonate systems. Ten facies/microfacies are grouped into two facies associations (FAs): FA1, tidal flat deposits consist of laminated sandstones/siltstones and floatstones with a single organism dominance (bivalve shells); and FA2 comprises fossiliferous rudstones, floatstones, packstones, and wackstones, representing a carbonate platform. The petrographic description determined rock textures/genesis and the diagenetic sequence with features of the eodiagenesis, mesodiagenesis, and telodiagenesis suggesting a primary origin of these carbonates. The analysis using cathodoluminescence (CL), energy disperse spectrometry (EDS), and scanning electron microscopy (SEM) allowed identify compositional differences, cementation phases, and morphological features in different processes as micritization, neomorphism, porosity, pyritization, compaction, cementation, fracturing, and weathering. The interpretation of facies and microfacies indicated a deposition mainly in a shallow platform with variation in the hydraulic conditions, warm waters, and episodic events of storms/tsunamis that fragmented the bioclasts. A shallow marine system in the Eastern Cordillera Basin during Cretaceous indicates a large transgressive event that flooded hundreds of kilometers, being a link with the Pacific Ocean before the Andes uplift. The main diagenetic events correspond to micritization, cementation of calcite, and mechanical/chemical compaction as a result of microbial activity, dissolution, precipitation in the vadose/phreatic zone, and burial diagenesis. The diagenetic sequence events reveal the incidence of marine and meteoric process that reduced porosity and attest to the microbial activity in carbonate precipitated. This new interpretation allows the understanding of carbonate platforms in the Eastern Cordillera Basin for future correlations of the Cretaceous sea in Colombia. Resumen La Formación Tibasosa es la principal fuente de calizas en Boyacá. Esta unidad se depositó entre el Valanginiano-Albiano según el contenido fósil en la Cuenca Cordillera Oriental, registrando la primera incursión del mar Cretácico en Firavitoba. Los análisis de facies y estratigráficos de una sucesión carbonática-siliciclástica de ~12 m de espesor de la Formación Tibasosa Superior indican sistemas mareales/carbonáticos. Diez facies/microfacies se agruparon en dos asociaciones de facies (AFs): AF1, planicie mareal consiste en areniscas/limolitas laminadas y floatstones con un solo tipo de organismo dominante (conchas de bivalvos); y AF2 comprende rudstones, floatstones, packstones y wackstones, representando una plataforma carbonática. La descripción petrográfica determinó la textura/génesis y la secuencia diagenética con características de la eodiagénesis, mesodiagénesis y telodiagénesis sugiriendo un origen primario de estos carbonatos. El análisis mediante catodoluminiscencia (CL), espectrometría de energía dispersa (EDS) y microscopía electrónica de barrido (MEB) permitió identificar diferencias composicionales, fases de cementación y características morfológicas en diferentes procesos como micritización, neomorfismo, porosidad, piritización, compactación, cementación, fracturamiento. y meteorización. La interpretación de facies/microfacies indicó una deposición en una plataforma poco profunda con condiciones hidráulicas fluctuantes, aguas cálidas y eventos de tormentas/tsunamis que fragmentaron los bioclastos. Este sistema deposicional en la Cuenca Cordillera Oriental durante el Cretácico indica un gran evento transgresivo que inundó cientos de kilómetros, revelando conexión con el Océano Pacífico antes del levantamiento Andino. Los principales eventos diagenéticos corresponden a la micritización, cementación de calcita y compactación mecánica/química como resultado de la actividad microbiana, disolución, precipitación en la zona vadosa/freática y diagénesis de enterramiento. La secuencia diagenética revela la incidencia de procesos marinos y meteóricos que redujeron la porosidad y corroboran la actividad microbiana en el carbonato precipitado. Esta nueva interpretación permite comprender las plataformas carbonatadas en la Cuenca Cordillera Oriental para futuras correlaciones del mar Cretácico en Colombia.
... Dissolution of marine carbonate from the seafloor alone could, in theory, generate the inferred decrease in seawater δ 44 Ca. The global Permian platform carbonate surface area is estimated to be~6 · 10 6 km 2 (Kiessling et al., 2003); in order for carbonate dissolution to explain the End-Permian trend globally,~100 m of platform carbonate (assuming a porosity of 0.5) must dissolve into the ocean over~130 ka. In a similar vein, Wang et al. (2019) recently proposed that subaerial weathering promoted by sea level regression explains the δ 44 Ca drop at the End-Permian as a global phenomenon. ...
Precise measurements of calcium (Ca) isotopes have provided constraints on Ca cycling at global and local scales and quantified rates of carbonate diagenesis in marine sedimentary systems. Key to applying Ca isotopes as a geochemical tracer of Ca cycling, carbonate (bio)mineralization, and diagenesis is an understanding of the impact of multiple factors potentially impacting Ca isotopes in the rock record. These factors include variations in stable isotopic fractionation factors, the influence of local-scale Ca cycling on Ca isotopic gradients in carbonate settings, carbonate dissolution and reprecipitation, and the relationship between the Ca isotopic composition of seawater and mineral phases that record the secular evolution of seawater chemistry.
... To clarify that, it requires not only complete biodiversity curves, but also more detailed onset processes of the radiations in both global and regional scales. Although both biotic and abiotic changes are thought to be controlling factors (Harper et al., 2015), abiotic factors may play more significant roles in the paleocontinental scale (Servais and Harper, 2018), such as intense tectonic and volcanic activities with abundant terrigenous nutrients into ocean (Miller and Mao, 1995;Vermeij, 1995;Miller and Connolly, 2001;Servais et al., 2009), increased ranges and more oxic conditions of platforms due to global sea-level rise (Barnes et al., 1996;Kiessling et al., 2003;Haq and Schutter, 2008;Nardin and Lefebvre, 2010), a global cooling event (Trotter et al., 2008;Rasmussen et al., 2016), and increased oxygen levels (Saltzman et al., 2015;Marenco et al., 2016;Edwards et al., 2017;Edwards, 2019). ...
The origin of reddish nodular limestone in the Zitai Formation, a deeper-water type of marine red beds (MRBs) distributed along the marginal Yangtze Platform, South China, is enigmatic. This paper will focus on the red colorations through sedimentological, mineralogical and geochemical analyses, as exemplified by the Zitai Formation at the Xiangshuidong section, Songzi City, Hubei Province and the Daling section, Shitai City, Anhui Province. Limestones studied here can be gray, green or red. The grayish limestones are generally below the reddish and/or greenish limestones, whereas the greenish layers are associated with reddish layers in forms of homogenous, banded or mottled limestone. Hematite that is fine and poorly crystalized could be the coloration mineral for the Zitai MRBs, which are largely caused by increased terrigenous iron, when the bottom seawater was oxic. Except that the irregular banded and mottled reddish-greenish limestone are of a possible diagenetic origin, the primary greenish limestones are related to relatively reducing conditions compared with reddish limestones, as a result from eustatic changes or other fluctuating environmental factors. During this time interval, the Great Ordovician Biodiversification Event (GOBE) was facilitated by highly oxic seawater indicated by MRBs in South China, Baltica and Sibumasu, but the diachroneity of radiations in South China could be ascribed to increased terrigenous supply, emphasizing that regionally environmental factors might be critical for biological radiations at the early stage of the GOBE.
Paleogene strata in Southwest Tarim Basin are important hosts of hydrocarbons with the highest quality reservoirs, a product of depositional environment, diagenesis and tectonics. The Paleogene interval is composed, in ascending order, of the Altash, Zimugen, Karatar, Wulagen and Bashbluk formations. Five facies associations are interpreted, respectively, as gypsum bay, alluvial fan-braided river, intertidal flat, supratidal flat and restricted platform. Stratigraphic evolution of Paleogene is recorded in vertical changes of sedimentary environment and climate. At least four transgressive–regressive cycles are recognized that can be correlated with the global eustatic changes. Detailed paleoenvironmental analysis laid a foundation for predicting the reservoir rocks in this mixed clastic–carbonate sequence. Braided channel sandstone and restricted platform grainstone constitute the best reservoirs in Paleogene. The most important diagenetic processes in sandstones that resulted in porosity and permeability changes are mechanical compaction, cementation, and dissolution of unstable clastic grains and cements, whereas in carbonate rocks, the dominant factors are cementation and dissolution. Tectonic fracturing developed in multiple stages in Paleogene has played an important role in improving the quality of reservoir rocks. Stratigraphic evolution of the Paleogene resulted in stacking of seal rocks above reservoirs during the late transgressive and regressive phases of sedimentation.
Designing carbonate facies models requires the integration, correlation and conceptual interpretation of multiple geological data sets. Potential significant errors are sourced from uncertain stratigraphic correlations, speculative palaeoecological interpretations and poorly recorded palaeotopographic profiles. The present study explores a methodological workflow to define a well-supported facies model. An exhaustive literature review is presented on sedimentary facies and depositional profiles of Urgonian carbonate platform from SE France and Switzerland (Barremian–Aptian interval). The historical evolution of Urgonian facies models and related sedimentological concepts is investigated to contextualise published models. The presented conceptual model and table of depositional facies shows a consistent, process-based organization of specific elementary facies, facies associations and carbonate system. Within the chronostratigraphic framework, the study of synchronous strata correlations provides quantitative analyses of facies-belt extents and palaeobathymetric estimations. The resulting depositional profile is based on general palaeoecological and sedimentological concepts, facies distribution on palaeogeographic maps and stacking trends. In rare locations in the field, direct lateral facies belt transitions are recorded. Proximal ( i.e. emersive and peloidal-foraminiferal) depositional facies are rarely observed; most outcrops record the (i) rudist facies association, which corresponds to distal parts of the inner platform, (ii) coral, ooidal and bioclastic facies associations, which are interpreted to occur on the outer platform, and (iii) calcisiltite, slope and basinal deposits. Key data and concepts allow for the building up of a robust, harmonised facies model that can be used to properly interpret palaeoenvironmental changes, stacking trends and stratigraphic sequence evolution, the resolution of which depends on the available chronostratigraphic framework.
We investigate how variations in a planet’s size and the chemical (mineral) composition of its upper mantle and surface affect processes involved in the carbonate-silicate cycle, which is thought to have regulated the composition of Earth’s atmosphere and its surface temperature over geologic time. We present models of geophysical and geochemical controls on these processes: outgassing, continental weathering, and seafloor weathering, and analyze sensitivities to planet size and composition. For Earth-like compositions, outgassing is maximized for planets of Earth’s size. Smaller planets convect less vigorously; higher pressures inside larger planets hinder melting. For more felsic mantles, smaller planets (0.5-0.75 Earth mass) outgas more, whereas more mafic planets follow the size trend of Earth’s composition. Planet size and composition can affect outgassing by two orders of magnitude, with variability driven by mass in the first 2.5 Gyr after formation and by composition past that time. In contrast, simulations spanning the diversity of surface compositions encountered in the inner solar system indicate that continental weathering fluxes are about as sensitive to surface composition or the patchiness of land as they are to surface temperature, with fluxes within a factor of five of Earth’s. Seafloor weathering appears more sensitive to uncertainties in tectonic regime (occurrence, speed, and size of plates) than to seafloor composition. These results form a basis to interpret calculations of geological surface carbon fluxes to track atmospheric compositions, through time, of lifeless exo-Earths, providing a baseline against which the effect of biological activity may be distinguished with telescopic observations.
Field investigation, biostratigraphic, paleoecological, and sedimentary microfacies analyses, as well as diagenetic processes characterization, were carried out in the Epirus region (Western Ionian Basin) to define the depositional environments and further decipher the diagenetic history of the Late Cretaceous–Early Paleocene carbonate succession in western continental Greece. Planktonic foraminiferal biostratigraphy of the studied carbonates revealed that the investigated part of the Gardiki section covers the Cretaceous–Paleogene (K-Pg) transition, partly reflecting the Senonian limestone and calciturbidites formations of the Ionian zone stratigraphy. Litho-and bio-facies analyses allowed for the recognition of three distinct depositional facies: (a) the latest Maastrichtian pelagic biomicrite mudstone with in situ planktonic foraminifera, radiolarians, and filaments, (b) a pelagic biomicrite packstone with abundant planktonic foraminifera at the K-Pg boundary, and (c) an early Paleocene pelagic biomicrite wackestone with veins, micritized radiolarians, and mixed planktonic fauna in terms of in situ and reworked (aberrant or broken) planktonic foraminifera. The documented sedimentary facies characterize a relatively low to medium energy deep environment, representing the transition from the deep basin to the deep shelf and the toe of the slope crossing the K-Pg boundary. Micropaleontological and paleoecological analyses of the samples demonstrate that primary productivity collapse is a key proximate cause of this extinction event. Additional petrographic analyses showed that the petrophysical behavior and reservoir characteristics of the study deposits are controlled by the depositional environment (marine, meteoric, and burial diagenetic) and further influenced by diagenetic processes such as micritization, compaction, cementation, dissolution, and fracturing.
May, A. (2022b): Why were reefs and stromatoporoids so rare in the Lower Devonian?. - Sciences of Europe, vol. 104: p. 24–32; Praha.
https://doi.org/10.5281/zenodo.7298618.
Abstract: In the middle Lower Devonian, the Pragian, reefs were very rare worldwide and stromatoporoids were rare and little diverse. As an explanation for this phenomenon, it is not sufficient that the global sea level had its low for the Devonian period during the Pragian and Lower Emsian. Therefore, three stromatoporoid-bearing reefs from the Pragian of Western and Central Europe were studied: Koněprusy in the Czech Republic, Seewarte in Austria and Zújar in Southern Spain. The following possible causes for the extreme rarity of reefs in the Pragian emerged: 1) Conspicuously high or low water temperatures that were not conducive to the growth of stromatoporoid reefs. 2) Stromatoporoid groups, which were of central importance in the Givetian and Frasnian reefs, were only at the beginning of their evolution and expansion in the Pragian – particularly mentioned are the branching stromatoporoids, the thinly encrusting stromatoporoids and the order Stromatoporellida. 3) There is evidence that the Syringopora commensals increased the reef-building potential of the stromatoporoids. There seems to have been a break in the Syringopora commensalism of the stromatoporoids in the uppermost Silurian or deepest Devonian. In the Pragian, Syringopora commensals were very rare and the Devonian Syringopora commensalism began with the primitive initial stage of Syringopora praehanshanensis May, 2005.
In this review article, it will be first summarized the basic information about Ibn Khaldun, and his famous book called “Muqaddimah” and share our modest thoughts on this great work to understand the essence and value of the book. This study aims to emphasize that the work of Ibn Khaldun is an important scientific source for humanities and social sciences, especially sociology and related majors. In short, the purpose of this modest article is to explain “Muqaddimah” as it is an invaluable resource for young researchers.
Karst bauxites over the world have significant economic value and the geodynamic controls of their formation have attracted wide attention. These deposits are distributed over a vast region in the Tethyan realm, formed in diverse geological times and tectonic settings under a relatively monotonous warm and humid paleoclimate. This study reviews the spatio-temporal distribution of karst bauxites and their geodynamic and paleoclimatic settings based on paleogeographic reconstruction of the Tethyan realm. We show that karst bauxites were mainly formed in three orogenic domains: (1) the Ural-Central Asia belt, which formed at low paleolatitudes during the Cambrian through Devonian controlled by the Proto-Tethys and the Paleo-Asian Ocean, and later during Carboniferous and Cretaceous-Paleogene at mid-high paleolatitudes influenced by the heat transport from Paleo-Tethys and Neo-Tethys via seaways, (2) the Carboniferous to Permian Eastern Asia belt and westerly younger late Permian to Jurassic Turkey-Iran-Afghanistan-Pakistan belt formed in low paleolatitudes within the region of Paleo-Tethys, and (3) the Late Cretaceous-Paleogene Mediterranean belt and Neogene Caribbean belt controlled by the evolution of Neo-Tethys. The spatial shift of bauxitization with time was controlled by the paleogeographic evolution of Tethys and the resulting changes of oceanic current circulation and paleoclimate. We identify common scenarios of diverse metallogenic models in specific geodynamic phases through a combined analysis of chronological data on detrital zircons and local sedimentological sequences. In the continental extension phase, basement rocks were exposed to provide dominant materials for the formation of bauxite deposits on eroded carbonate platforms along continental margins. In the oceanic subduction phase, the arc volcanism provided abundant volcaniclastic materials, especially for the bauxite deposits on isolated carbonate platforms. In the arc accretion phase, weathered remnants were transported from complex nappes into intracontinental carbonate depressions. The karst bauxite deposits originally formed in a specific tectonic stage were superimposed by later tectonic reworking, and were metamorphosed, or exposed, disrupted, eroded, redeposited and altered during later continental collision stage, whereas incipient bauxite accumulation restarted during post-collisional extension phase. These processes occurring within the similar favorable paleoclimatic background define a unified metallogenic system concomitant with Wilson cycle that explains the spatio-temporal distribution of karst bauxites in the Tethyan realm.
The Late Jurassic–Early Cretaceous is an interval of unstandardized stages and includes the only Mesozoic system boundary without a Global Boundary Stratotype Section and Point – the Jurassic/Cretaceous (J/K) boundary. Recent researches have been mainly focused on deep marine continuous successions from the Tethyan region and provided important progress in calibration of pelagic bioevents. Correlation of these pelagic zonations with the schemes from shallow marine deposits is still obscure. Biostratigraphical data from marginal carbonates containing fossils both from the platform and basinal facies can provide the required links between these two distinct depositional environments. This kind of Upper Jurassic–Lower Cretaceous carbonates widely crop out in the Pontides (northern Turkey) in close association with related shallow and deep marine successions. A biostratigraphical dataset including 17 stratigraphical sections from this Pontides Carbonate Platform is synthesized. The fossil data include organisms from various depositional environments (i.e., benthic and planktonic foraminifers, calpionellids, algae, microencrusters and crinoids) and provides 139 bioevent datums (stratigraphic levels). This fossil dataset is analyzed through the methods of Graphic Correlation (GC) and Unitary Associations (UA) in order to overcome facies (past depositional conditions) controlled local biohorizons and calibrate fossil datums from unrelated phylogenies. Calibration of the Pontides Composite Reference Section (CSRS) with the Geological Time Scale (2020) reveals relative positions of both shallow and deep marine bioevents with respect to the Oxfordian–Hauterivian stage boundaries. The Tithonian/Berriasian and the Berriasian/Valanginian boundaries can be easily delineated by calpionellid bioevents in pelagic successions. However, no synchronous shallow marine first/last occurrence bioevents are available for both of these levels. Increased rates of originations toward Berriasian provide clustering of bioevents around the Tithonian/Berriasian boundary and brackets for both pelagic and shallow marine deposits. Several last occurrences provide unreliable approximations for the Berriasian/Valanginian boundary in neritic deposits. The species richness declines mid-Berriasian onward in accordance with the general trend toward lower sea levels through the late Tithonian into the Valanginian that diminished shallow marine factories and paved the way for a general Valanginian–Hauterivian drowning phase for the Tethyan carbonate platforms. This also adds difficulties in finding reliable origination events in the shallow marine environments for this extinction dominated interval.
This paper examines the evolution and the drowning history of late Lower to Upper Cretaceous carbonate platforms in the Gulf of Hammamet, belonging to the North eastern of Tunisia based on seismic and well data sets. We use seismic architecture, well log data and micro-fauna to reconstruct factors that governed the growth and demise of the platforms. Platform evolution reflects four stages: (1) initial installation, (2) platform aggradation, progradation and retrogradation, (3) coalescence and extension, and (4) burial by Cenozoic siliciclastic deposits. Interpretations of seismic facies help to define platform history indicating that the area of study originated since the Jurassic time as three small platforms on extensional fault-blocks separated by deep seaways. Eustatic sea-level changes controlled the timing of sequence boundary establishment. Nevertheless, tectonics modified facies distributions and stacking patterns. Faulting-controlled the substrate morphology, forming-sites for the development of platform deposits and providing bottom for the localization of backstageped platforms. Faulting may also have caused progradation of the platforms as a result of a slowdown in the creation accommodation space. The net platform extension and backstageping may be controlled by regional subsidence. Progradation is highly developed on the leeward sides of the platforms, but increased accommodation resulting either from rapid local subsidence or changing oceanographic currents also influenced the direction and magnitude of the results.
Atolls are faithful recorders helping us understand eustatic variations, the evolution of carbonate production through time, and changes in magmatic hotspots activity. Several early Cretaceous Mid‐Pacific atolls were previously investigated through ocean drilling, but due to the low quality of vintage seismic data available few spatial constraints exist on their stratigraphic evolution and large‐scale diagenesis. Here we present results from an integrated core‐log‐seismic study at Resolution Guyot and comparison with modern and ancient analogues. We identify six seismic stratigraphic units: (1) platform initiation with aggradation and backstepping through the Hauterivian which ended by platform emersion; (2) reflooding of the platform with progradation and aggradation through the Barremian till the early‐Aptian when ocean anoxic event 1a resulted in incipient drowning; (3) platform backstepping till the mid‐Aptian when the platform shifted to progradation and aggradation till the mid‐Albian; (4) platform emersion; (5) reflooding with backstepping ending at the latest‐Albian by platform emersion; and (6) final drowning. The stratigraphic surfaces bounding these units are coeval with some of the Cretaceous eustatic events which suggest an eustatic control on the evolution of this atoll and confirm that several previously reported sea‐level variations in the early Cretaceous are driven by eustasy. Changes in subsidence and carbonate production rates and suspected later magmatism have also impacted the stratigraphic evolution. The suspected later magmatism could lead to environmental perturbations and potentially platform demise. Contrary to previous studies we identify two emersion events during the mid‐ and late‐Albian which resulted in intensive meteoric dissolution and karstification. The platform margin syndepositional fractures interacted with the subaerial exposure events by focusing the dissolution which formed vertically stacked flank‐margin fracture‐cave system. The study gives a unique insight on the interplay between eustasy, subsidence, and volcanic activity(ies) on long‐term evolution of early Cretaceous shallow‐marine carbonates. It also documents the impact and distribution of hypogenic and epigenic fluid‐flow in atolls serving as an analogue for isolated carbonate platforms.
Congo and São Francisco cratons are made of several Archean and Paleoproterozoic nuclei welded together by Paleoproterozoic belts. The pair is considered to be a stable lithospheric entity by ~2.0 Ga and hosts fissural mafic magmatism at 2.7–2.6, 1.71, 1.50, and 0.92 Ga; magmatic events at 1.38 and 1.10 Ga are restricted to Africa. Some of these dike swarms and also younger sedimentary units have been targeted for paleomagnetic studies, but the paleomagnetic data for the Congo−São Francisco craton is still scarce. Here we review the available data for both cratons. A total of 21 paleomagnetic poles was selected for paleogeographic reconstructions, 11 of them with Q-index higher than 4. Segments of apparent wander paths were drawn for 1.1–0.92, 0.79–0.74, and 0.57–0.52 Ga. Tentative reconstructions are proposed to place Congo−São Francisco into the context of supercontinents Columbia, Rodinia, and Gondwana.
In Southern Alberta, the Tournaisian Banff Formation overlies the argillaceous and silty Exshaw Formation; it is overlain by the cliff-forming Pekisto or Livingstone Formations of the Rundle Group. The Exshaw-Banff interval represents an argillaceous, recessive interval wedged between two massive carbonate sequences, the Devonian Wabamun-Palliser and the upper Mississippian Rundle Group. The Banff corresponds to a shallowing-upward megasequence interpreted as a prograding carbonate ramp. Two paleogeographical realms are recognized in the Banff and Rundle: an eastern and a western domain. Within the Banff Formation a transgressive event is well marked by a radioactive shale unit at the base of the second mesosequence in the eastern region and by the occurrence of grainflow crinoidal grainstone beds at the top of the middle member in the western region. The lower Carboniferous sedimentation is structurally controlled while the boundary between the two realms migrates to the west through time. -from Author
A new Cambrian section has been exposed by Lemok BH-1, drilled on the left bank of the Yenisei River downstream from the mouth of the Angara River. Its lower part is saliniferous, and the upper one is made up of variegated deposits. They are similar to the rocks of the Usol'e and Evenki Formations (Siberian Platform), respectively. These parts of the section are separated by a sequence of sulfate-carbonate and carbonate deposits containing shell debris and fragments of algal colonies. Trilobites Binodaspis cf. paula Suvorova and Bonnaria sp. as well as olenellids have been found in the depth range of 2804.4-2805.9 m. They indicate the Botomian age of the host rock. We performed correlation of the sections of deep boreholes drilled on the left bank of the Yenisei River: Tyiskaya BH-1, Lemok BH-1, Eloguiskaya reference borehole, and Malokhetskaya BH-11. The correlation provides a basis for an independent scheme of Cambrian stratigraphy for the region under consideration. The Lower Cambrian includes four formations: Usol'e, Tyya, Averina, and Antsiferovka. The last three formations are proposed by us. They correspond to the Atdabanian, Botomian, and Toyonian, respectively. The Elogui Formation was formerly proposed for the lower Middle Cambrian (Amgaian). It is overlain by the Evenki Formation. It has been demonstrated that in the Early and early Middle Cambrian, the left bank of the Yeniseri River was occupied by a vast carbonate platform (barrier reef). It separated the salt deposition basin of the Siberian Platform (continent) in the east from the oceanic water area open to the west. Volcanic rocks typical of back-arc basins have been found close to the margin of the Siberian continent in the Vezdekhodnaya area.
Each sequence consists of a lowstand-systems tract, a transgressive-systems tract and condensed section, and a highstand-systems tract. Increased subsidence from the Middle Miocene onward caused the retreat of the Natuna Platform. Platform retreat occurred incrementally, during deposition of transgressive-systems tracts and the condensed sections. The large eustatic sea-level rise in the early Pliocene, combined with continued rapid subsidence, drowned the platform and ended carbonate sedimentation. -from Authors
The middle Bajocian to middle Bathonian epicontinental sediments of northern Switzerland consist of shallow-marine oolitic carbonates (Hauptrogenstein Formation, Celtic realm) and marly basinal deposits (Klingnau Formation, Swabian realm). Detailed biostratigraphic data based on ammonites and dinoflagellates provide a time frame for a sedimentologic analysis. The carbonate series of the Celtic realm is composed of three shallowing-upward successions, each capped by a hardground. In the basinal domain east of the Aare River, marls persist in a monotonous facies throughout the same time period. The first shallowing-upward succession within the Hauptrogenstein Formation, started during the Blagdeni Subzone with marly beds and intercalated tempestites (Rothenfluh Beds), covered in the western Jura by finegrained, bioclastic tempestites (Grenchenberg Beds). Simultaneously, the Gislifluh Reef developed in the southeastern Jura, probably on a morphologic high. Oolitic sedimentation started in the central Jura during the Niortense/Subfurcatum Zone (Lower Oolitic Series). The units of 0.5-2 m thick, cross-bedded oolites are attributed to a tidal, shallow-marine, high-energy setting. At the same time, the oolitic beds in the eastern Jura contain up to 35% of mud, and a low-energy setting is inferred (Lower Acuminata Beds). During the Garantiana Zone oolite-belts prograded eastwards reaching the area of the Aare River. An up to 70 m thick oolitic succession was deposited during a period of moderate sea-level rise and a steady subsidence. The second shallowing-upward succession started in the early Parkinsoni Zone. The production of ooids ceased during a sea-level highstand and marls and bioclastic limestones accumulated in northern Switzerland: the Homomya Marls in the western and the Upper Acuminata Beds in the central and eastern Jura. Later, a drop in relative sea-level during the late Parkinsoni Zone re-established ooid production (Upper Oolitic Series). The third shallowing-upward succession started during the latest Bajocian and earliest Bathonian (Zigzag Zone). Marly sediments rich in coarse bioclasts (Movelier Beds) are again interpreted as formed during a relative sea-level highstand. They are overlain by micritic oncolites in the western Jura; to the east, sparry bioclastic, locally cross-bedded limestones occur ("Spatkalk"), probably deposited by storms and tides. The deposition of the "Spatkalk" lasted until early Middle Bathonian, prograding eastward and covering the top of the basinal Klingnau Formation. The facies belts within the Hauptrogenstein and Klingnau Formations suggest the evolution of a middle Jurassic, north-south trending oolitic barrier dominated by tides. Backbarrier facies belts formed to the west and off-barrier assemblages to the east of this barrier. A decrease in the production of sediments, as evidenced by platformwide facies changes and in the thickness of shallowing-upward successions, was probably caused by changes in water circulation and local climate. On the other hand, more or less abrupt lateral changes in thickness and facies within the successions suggest local and regional patterns of differential subsidence.
Thirty-two maps have been constructed which depict the plate tectonic configuration, paleogeography and selected lithofacies for Phanerozoic time intervals from the earliest Cambrian through the Neogene. The plate tectonic maps illustrate geodynamic evolution of the Earth from the disassembly of Rodinia-Pannotia during Sauk time through closure, assembly, reorganization and formation of Pangean supercontinent during Tippecanoe, Kaskaskia and Early Absaroka times, rifting, spreading and disassembly during Late Absaroka and Zuni times, and new closure during Tejas time.
The Earth’s climate reflects the plate tectonic phases of continental breakup and assembly. The climate changed from a greenhouse with short icehouse interlude through icehouse with warming interludes, and another greenhouse, to the present day icehouse.
The global carbonate production of reefs is applied as a measure of the health of the reef ecosystem in a given time interval. Hence global reef crises are defined as significant drops in the global reefal carbonate production. This definition differs from the measure of diversity to detect evolutionary crises and mass extinctions, and it has two major implications: (1) Reef crises may be linked to mass extinctions defined by global biodiversity decreases, but are not necessarily so. (2) Reef crises can take place during very short time intervals linked to catastrophic events, but they can also extend over prolonged periods of time.
Our PaleoReefs database was used to calculate reefal carbonate production on a stage level and to quantify Phanerozoic reef crises. We determined eight first-order reef crises (carbonate production loss > 90%) (in decreasing order of magnitude) at the Triassic-Jurassic, Permian-Triassic, end-Ordovician, Pliensbachian-Toarcian, Mississippian-Pennsylvanian, Frasnian-Famenman, Berriasian-Valangin-ian, and Artinskian-Kungurian boundaries. Second-order reef crises (loss 75–90%) were seen at the Middle-Late Permian, Cenomanian-Turonian, and Valanginian-Hauterivian boundaries.
The magnitudes of reef crises and global marine diversity losses may differ substantially. As evidenced for the Cretaceous-Tertiary boundary, synecological patterns in reefs are not necessarily interrupted by mass extinction events. Although many reef crises coincide with major mass extinction events, some crises are associated with only minor extinctions or even with evolutionary radiations (Middle Ordovician, Early Permian). Reef crises affect all reef builders, including corals, sponges, and bivalves. Even microbes are not necessarily disaster forms that survive reef crises. The paleogeographic reef distribution pattern is nearly always constricted during major reef crises. The most commonly observed pattern is a latitudinal narrowing and northward shift of the reef zone. The geographic range of reefs prior to the crisis had no influence on the magnitude of the crisis.
Applying the criteria for reef crisis to reef recovery, we define reef recovery as the time when a first significant increase in the global reef carbonate production becomes evident. Reef recovery usually takes a substantially longer time than the recovery of global biodiversity and is in the range of 5–30 million years. Recovery time is nearly independent of crisis intensity in the reef ecosystem.
The Permian sequence of the Transcaucasia, which comprises the Davaly, Asni, Gnishik, Arpa, Khachik, and Akhura Formations, is described. A precise dating of the formations based on the analysis of fusulinid assemblages is also provided. The Davaly Formation corresponds to the Bolorian Stage of the Lower Permian (Cisuralian); the Asni Formation corresponds to the Kubergandian Stage, and to the lower half of the Murgabian Stage of the Middle Permian (Guadalupian); the Gnishik Formation corresponds approximately to the upper half of the Murgabian Stage; and the Arpa and Khachik Formations represent the entire Midian Stage of the Middle Permian. Only the uppermost Chanakhchy Beds of the Khachik Formation are referred to the upper series of the Permian (Lopingian), based on the latest proposal of the International Subcommission on Permian Stratigraphy concerning series boundaries. The Akhura Formation encompasses the Dzhulfian and Dorashamian Stages of the Upper Permian. Refined correlations between the Permian sequence of the Transcaucasia and the most complete Permian sequences of the Tethyan region (Central Iran, southestern Pamirs, South China, Japan) are presented. The transgressive overlapping of the Permian deposits is recorded in these areas, similar to the Transcaucasia. Although the transgression began during the Bolorian, it reached the widest extent in the Kubergandian and therefore, in most sections the transgressive series begins with deposits of Kubergandian age. The Middle and Upper Permian deposits of the Transcaucasia, Iran, and southern Turkey belonged to a single carbonate platform. Similar extensive carbonate platforms are recorded in the southern parts of Afghanistan and China. A change in the sedimentary regime was recorded in all these platforms at the boundary between the Guadalupian and Lopingian epochs. The Guadalupian time was marked by the intensive accumulation of biolitithic and detrital limestones produced by benthic organisms, mainly algae and foraminifers, whereas in the Lopingian time, carbonate and clayey micritic deposition dominated, and the role of nectonic-planctonic and nectonic organisms, such as cephalopods and conodonts, increased. The sedimentation change was abrupt and caused probably by the short-term post-Midian regression. The change resulted in a significant biotic crisis when larger fusulinids, goniatitids and agoniatitids, tabulate corals, most rugose corals and other organisms became extinct. These events marked the onset of the Late Permian 'Great Extinction', which ended at the Permian/Triassic boundary. Nine paleontological plates show the main fusulinid assemblages. Nine new species are described: Codonofusiella (?) vediensis, Chalaroschwagerina davalensis, Pseudofusulina arpaensis, P. araxensis, P. pjatakovae, Rugosochusenella davalensis, Misellina (Misellina) caucasica, Cancellina armenica, and Sumatrina vediensis.
Two stratigraphic units in the Hunton Group contain reservoirs in Mt. Everette and Southwest Reeding fields: the Chimneyhill Subgroup (Early-Late Silurian), and the Henryhouse Formation (Late Silurian). The Chimneyhill Subgroup is an upward-shoaling sequence, at the top of which are hydrocarbon-bearing, crinoid-rich, skeletal-buildup reservoirs of the Clarita Formation. These buildups contain biomoldic and other solution porosity created during subaerial exposure and dolomitization prior to Henryhouse sedimentation.
Spectacular conical Early Devonian carbonate buildups up to 55 m high that crop out in the eastern Anti-Atlas of southern Morocco are microbially mediated carbonate mud mounds that were surfaced by soft-bottom communities dominated by small tabulate corals. They formed on the Hamar Laghdad elevation, which was created by a submarine volcanic eruption, and were associated with a network of synsedimentary radial and tangential faults that originated by uplift of the intrusive laccolithic body underlying the Kess-Kess Formation. These faults served as conduits for the migration of hydrothermal fluids to the sea floor. Most mounds developed over cross-points of radial and tangential faults. Vents were episodically active until the Famennian, but extensive vent carbonate production occurred only during the Emsian. Preliminary geochemical results document that mudmound carbonates and cakite cements in neptunian dikes precipitated from brines comprising a mixture of hydrothermal fluids and seawater. In addition, carbon isotope compositions (8I3C as low as -18%c PDB) suggest a contribution from thermogenic methane derived presumably from underlying basaltic intrusives. Aerobic bacterial oxidation of methane is favored as the main process driving carbonate precipitation in, and rapid lithification of, the mounds.
In most studies, tidal deposits are associated with shallowwater coastal areas. In contrast, this paper illustrates an ancient deepwater tidal environment located on the outer part of the Jura shelf. The Bajocian (mid-Jurassic) sediments are composed of fine-grained marly limestones that include several crinoidal limestone bars. These bioclastic bars are formed by stacked dunes and sand waves showing sedimentary structures typical of tidal environments. In order to interpret the sedimentology of the crinoidal limestones, the hydrodynamic behavior of crinoidal particles was investigated. Derived from a sedimentological, petrographical, and paleontological approach of the area, the results indicate that dunes and sand waves formed on the outer shelf at a depth of about 100-150 m under the occasional influence of tidal currents. Interpretation of seismic reflection data indicates a shelf-edge position located about 15 km to the SE.
Four contrasting carbonate sequences developed in a tectonically active, extensional setting in the Lower Cretaceous (AptianAlbian) Castro Urdiales platform of north Spain. The four carbonate phases (P1-P4; early Aptian, late Aptian, earliest Albianearlylate Albian, respectively) are identified across the platform-to-basin transition on the basis of sedimentary geometries and internal facies patterns. They are vertically separated by four incipient drowning events (D1-D4; middle Aptian, Aptian-Albian boundary, early Albianlate Albian). The first carbonate stage (PI) corresponds to a lowrelief carbonate platform characterized by widespread shallow-marine depositional environments with a nearly flat organization. The second platform stage (P2) developed as a rimmed carbonate platform. The third carbonate stage (P3) evolved from a low-relief aggradational platform (substage A) to a progradational offlapping platform (substage B)back to a backstepped, aggradational rimmed platform (substage C), responding to changes in differential subsidence and carbonate production. At the beginning of the Albian the Castro Urdiales carbonate platform was broken up by extensional tectonic movements with formation of fault blocks bounded by NE-SW and NW-SE trending faults. On the crests of uplifted blocks meteoric processes were active, whereas grabens and half grabens acted as channel conduits for terrigenous-rich deposits. Subsidence rates increased during the late early Albian-late Albian. The crests of rotated blocks formed paleohighs that nucleated small residual carbonate platforms (carbonate stage P4) that were surrounded by deeper-water basins. This study suggests that the evolution of carbonate platform sequences in the Lower Cretaceous of Castro Urdiales was primarily controlled by changes in accommodation space, which were most likely driven by intraplate stresses related to extension in the north Spanish continental margin during the opening of the N7orth Atlantic. Drowning events in the Castro Urdiales platform coincide with major crises of Cretaceous carbonate production worldwide, suggesting that regional tectonism and global oceanic changes interacted to cause phases of platform demise.
Sequence stratigraphic models are used to interpret stratal architecture and key stratal bounding surfaces in ancient carbonate platforms within the context of changing accommodation space during third-order relative sea-level cycles. However, individual systems tracts are still described using standard microfacies that give a snapshot of limestone composition, but they do not take into account gradual changes in the marine environment resulting from variations in water depth during the cycle of relative sea-level change. Water depth is the single most significant collective control on a wide range of environmental gradients affecting carbonate sediment composition. During dynamic relative sea-level fluctuations stratigraphic changes in carbonate sediment composition are characterized by systematic shifts in the relative importance of different limestone component grain types, forming temporal continuums or relays. Relays are detected using computer-optimized Jaccard's similarity coefficient matrices to analyze presence/absence compositional data. Individual relays between grain types may link together samples that are generically unrelated to one another but are nevertheless genetically related to deposition during the same unidirectional dynamic environmental gradient. A stratigraphic relay identified within the basal beds of the mid-Cretaceous Urgonian carbonate platform succession of SE France records unidirectional environmental gradients linked to changing water depth, characteristic of a transgressive systems tract. Periods of static water depth, such as the keep-up phase of a late highstand systems tract at the top of the Urgonian carbonate platform succession, are characterized by fixed compositional assemblages. Stratigraphic breaks between individual compositional relays and assemblages occur at inflections in changing water depth, marking the boundaries between individual systems tracts and sequences, currently identified using stratal geometries and key stratal surfaces. The use of relays to model microfacies and identify individual system tracts and sequence boundaries has several advantages over existing methods. This approach can be used where key stratal surfaces are difficult to distinguish, such as in planar and concordantly bedded, inner platform settings and in arid depositional environments where physical evidence of subaerial platform exposure such as karstification is poorly developed. The technique can also be used to determine the genetic significance of unconformities preserved in outcrop or core within a sequence stratigraphic context by differentiating unconformities formed at the extremes of relative sea-level cycles from those formed by other abrupt acyclical environmental changes.
This article summarizes the lithostratigraphy of two sections through the Kapp Starostin Formation on Spitsbergen having contrasting distal and proximal depositional settings. These outcrop sections are compared with an approximately age-equivalent spiculitic unit penetrated in two exploration wells 800 km to the southeast on the Finnmark Platform. Eight main facies associations comprise these strata, including limestones (matrix-rich, matrix-poor, and mudstone), siliciclastics (shale and sandstone), spiculite (dark/tight and light-colored/porous), and phosphatized surfaces. A sequence stratigraphic model is proposed wherein siliciclastic-limestone intervals represent lowstands of relative sea level, and the spiculites are mainly highstand deposits. Based on this model, seven depositional cycles (sequences) are recognized in the distal, high-accommodation locality on Spitsbergen (Akseloya), four in the proximal locality (Dickson Land), and two on the Finnmark Platform. A speculative model for correlation between these localities is presented, wherein lateral amalgamation of sequences, due to landward pinch-out of some lowstand intervals, results in recognition of fewer sequences in areas of lower accommodation. On both Dickson Land and the Finnmark Platform, an upward change in spiculite lithology from dark/tight to light/porous is shown, and Dickson Land also shows an upward change in siliciclastic lithology from shale to glauconitic sandstone. These changes record a long-term shoaling trend approaching the Permian-Triassic boundary. This model provides a basis for interpreting the basin-scale (Begin page 2062) distribution of lithofacies and predicting the occurrence of porous zones representing potential hydrocarbon reservoirs.
Allen Bay and overlying Read Bay shelf carbonate rocks and their lateral northward transition to basinal clastic rocks of the Cape Phillips are well exposed on Cornwallis and Griffith Islands. The exposures of Silurian shelf to basin strata on Cornwallis may be unexcelled anywhere in the world for this part of the stratigraphic record. Allen Bay carbonate rocks, approximately 6,000 ft (1,830 m) thick, consist largely of dolomite. Brachiopods suggest a Silurian (Wenlockian to Ludlovian) age for the middle and upper Allen Bay. Detailed outcrop studies led to the recognition of five main depositional facies and 15 lesser facies, despite pervasive dolomitization. Vertical and lateral changes of facies are described in terms of four transitional depositional stages. Deposition took place in environmental settings ranging from restricted interior algal flats and shelf-edge sabkha islands to unrestricted basins. Normal marine deposition on the carbonate shelf and shelf edge occurred in a variety of high- and low-energy environments. Between shelf and basin, slopes were very low, particularly during lower Allen Bay deposition, but may have been more pronounced through deposition of the middle Allen Bay when a dolomitized shelf-edge reef complex provided a relatively effective barrier. In general the sedimentation rate in the basin and slope apparently kept pace with that of the carbonate shelf throughout Allen Bay and lower Read Bay deposition. The amount, type, and degree of thermal alteration of organic matter in the Allen Bay and transitional Allen Bay-Cape Phillips facies appear to have been optimum for generation of both oil and gas. Greater values of porosity in the Allen Bay are particularly common at the shelf edge and in dolomitized carbonate sands and patch reefs of the interior shelf. Reduction in porosity in a shelfward direction, particularly for the middle Allen Bay, is interpreted as related primarily to change from dolomitized carbonate sand to finer textured protected-shelf and algal-flat facies. Dolomitization of Allen Bay carbonate rocks is related primarily to intrastratal mixing of marine and hypersaline water with fresh water.
The southern Alps of Italy preserve a tectonically intact array of Jurassic facies that record the evolution of a part of the margin of the Apulian plate from its ancestral beginnings in a complex of Permian and Triassic rifted continental basins through the initial stages of breakup and stepwise foundering of a carbonate platform. Breakup was accompanied first by the rapid accumulation of thick prisms of carbonate turbidites in newly formed fault troughs. Then, as the new Ligurian oceanic basin began to open farther west and, as subsidence gradually slowed, accumulation of a succession of slowly deposited biogenous pelagic sediments recorded not only the increasing depths of the seafloor but also fluctuations in oceanographic conditions of fertility, carbonate dissolutio levels, and the strength of bottom currents. Estimates of the history of seafloor depths, based on a simple subsidence law of the form Subsidence = K(Age)12/, provide a basis for the construction of a set of curves showing the changing depths of significant carbonate dissolution surfaces during the Jurassic in this region. The rapid 1-km deepening of the compensation depth for calcite during the Late Jurassic may be due to a change in regional oceanic vertical circulation patterns from upwelling (fertile, silica-rich, carbonate dissolving) to downwelling (less fertile, silica-poor, carbonate preserving).
Carbonate platforms were one of the most characteristic paleoenvironments of the Tethyan domain. From Permian to Late Cenozoic, the permanence of warm marine conditions in this domain have favored thriving shallow-water skeletal benthic communities and accordingly, the carbonate sedimentation.
Recognises three types of carbonate buildups, including platform-margin reefs, organic mud mounds, and patch reefs. Carbonate buildups in the Changxing Formation have yielded natural gas. Distribution and nature of these buildups were controlled by movement of basement blocks along paleorift zones. Paleotopographically high blocks west of the rift became silts of carbonate platforms upon which patch reefs developed in the Late Permian. Dolomitisation is most extensive in the platform-margin reefs and these contain the best hydrocarbon reservoirs. -from Authors
The first detailed history of relative sea-level changes known from lower Paleozoic strata in Antarctica is documented in this study of the Nelson Limestone. Basal beds of the formation constitute a nonmarine terrigenous valley-fill succession. Thickness of these strata varies from 0.1 m to 72 m, suggesting that significant topographic relief existed below the sub-Nelson unconformity. Locally, base level must have risen at least 72 m because, following fluvial infilling of the valley, a succession of carbonates over 400 m thick was deposited as seas inundated the Antarctic margin of Gondwana during late Middle Cambrian time. In the Nelson Limestone, smaller fluctuations of relative sea level are indicated by three sequences, each about 100 m thick. The lower sequence is bounded below by the sub-Nelson unconformity and includes the valley-fill succession, transgressive sandstone, and highstand carbonate deposits. Following marine flooding, an offshore carbonate shoal with an associated restricted lagoon was established during deposition of the middle sequence. The upper sequence records marine flooding above the middle sequence and subsequent reestablishment of an offshore carbonate shoal prior to deformation and volcanism in the area related to the Ross Orogeny. -from Authors