Project

IGCP 652 Reading Geologic Time in Paleozoic sedimentary Rock

Goal: Major events punctuated the Paleozoic: ecological crises and diversifications, shifts in ocean chemistry, climatic changes, etc. One of the key-obstacles in understanding these events lays in the difficulty of providing precise estimates of the duration represented by a sequence of Paleozoic sedimentary rocks. This lack of temporal precision severely hampers the evaluation of forcing mechanisms and rates of climatic, ecological or biogeochemical changes in the Paleozoic. It is therefore essential to first improve the Paleozoic timescale to then unravel the history of the Paleozoic Earth system.

Cyclostratigraphy is a powerful chronometer, based on the detection of the Milankovitch cycles in the sedimentary record. Those cycles result from periodic variations in the Earth-Sun system, affecting the distribution of solar energy over the Planet influencing Earth’s climate on time scales between 104 and 106 years. Through the integration of this astronomical time scale with biostratigraphy and radio-isotopic dating, this project intends to document the environmental evolution during the Paleozoic with a focus on the Ordovician to Devonian (485 – 359 million years). It gathers participants (> 200) from all over the world (36 countries) and promotes the participation of young scientists and scientists from developing countries.

Date: 22 March 2017 - 31 December 2020

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Project log

Peter Königshof
added a research item
The Bayankhoshuu Ruins section in southern Mongolia is characterized by strongly thrusted and folded sequences. Overall, three sections ranging from Ordovician to Carboniferous rocks were studied. Facies analysis combined with stratigraphic data provide improved lithostratigraphic descriptions of Palaeozoic successions in the Mushgai region. The overall marine sedimentary sequence is punctuated by volcanic rocks – basaltic lava of Silurian and Middle Devonian age and volcaniclastic bentonite and tuff in the Middle to Late Devonian and Mississippian suggesting an island arc setting. The Minjin Member of the Botuulkhudag Formation (Middle Devonian to Late Devonian) is primarily composed of thick basaltic and subaerial volcanic rocks with minor silicified siltstone and chert inclusions. Thicker successions of limestone occur in the Ordovician/Silurian, Early Devonian, and the Mississippian. The macrofauna is scarce, except distinct limestone horizons where different fossil groups were recognized. Microfossils, such as radiolarians and conodonts, are scarce and generally poorly preserved. However, based on the re-study of collections from earlier publications and new conodont data, a more detailed biostratigraphic record of the Khoyormod, Botuulkhudag, and Arynshand formations of the Bayankhoshuu Ruins section can be developed. For instance, the Arynshand Formation likely ranges from the late Bispathodus ultimus conodont biozone to the Scaliognathus anchoralis – Doliognathus latus conodont biozone. A tectonic breccia occurs in the early Mississippian and is overlain by a red shale of remarkable thickness at the top of this formation which points to subaerial exposure in the early Mississippian (near the Tournaisian/Visean transition). Due to strong tectonic overprint and/or facies, some unconformities/hiatuses occur. Most strata are intensively folded and faulted, ranging from centimeter to meter scale. Overall, deposition likely occurred on either the Mandalovoo or Gurvansayhan Terrane.
Peter Königshof
added a research item
A Late Devonian to (?)Early Mississippian section at Hushoot Shiveetiin gol in the Baruunhuurai Terrane of the Central Asian Orogenic Belt (CAOB) exposes large parts of cyclic Famennian shallow-water siliciclastic shelf deposits composed of siltstones, sandstones, shales, volcaniclastics, and intercalated autochthonous carbonates. The youngest part of the section, possibly Early Mississippian, is represented by arkosic sandstones with large plant remains. The facies reflects a range from shallow-intertidal to outer ramp settings. In terms of conodont stratigraphy, the Hushoot Shiveetiin gol section ranges from the Palmatolepis minuta minuta Biozone to at least the Palmatolepis rugosa trachytera Biozone. Hiatuses of several conodont biozones occur due to the facies setting (erosion and reworked sediments which are recognized by reworked conodonts) rather than thrusting or folding. The environmental setting was characterized by coeval subaerial volcanism resulting in numerous pyroclastic deposits. The depositional environments and intense volcanic activity at the Hushoot Shiveetiin gol section limited the stratigraphic distribution, abundance, and diversity of many elements of the fauna such as brachiopods. Ostracods were very abundant and diverse through many parts of the section. Although limited in stratigraphic distribution, the crinoid fauna is the most diverse Palaeozoic fauna collected from Mongolia to date and supports the hypothesis that the CAOB was a biodiversity hotspot in the aftermath of the Frasnian-Famennian extinction event.
Peter Königshof
added a research item
An Upper Devonian to (?)Lower Mississippian section at Hushoot Shiveetiin gol in the Baruunhuurai Terrane of the Central Asian Orogenic Belt (CAOB) was investigated. A generally well-preserved and diverse ostracod fauna was collected from the Late Devonian (Famennian) Samnuuruul Formation in western Mongolia. It is the first rich assemblage described from this area. The ostracod fauna consists of 19 genera and 25 species. Two of the species are proposed new species, and 13 species are described in open nomenclature. The Mongolian ostracod fauna is similar to coeval faunas in western China and Laurussia, but also contains new, endemic species. Two new taxa are described: Beyrichiopsis hushootensis and Ampuloides beckeri. Ostracod findings are characterized by the Eifelian Mega-Assemblage (I-III) representing a nearshore, variable palaeoenvironment which is in accordance with facies analysis provided by other studies.
Shuang Dai
added an update
Thanks a lot to my colleagues for help during the meeting.
 
Michael T. Whalen
added 4 research items
The Cretaceous/Palaeogene mass extinction eradicated 76% of species on Earth1,2. It was caused by the impact of an asteroid3,4 on the Yucatán carbonate platform in the southern Gulf of Mexico 66 million years ago 5 , forming the Chicxulub impact crater6,7. After the mass extinction, the recovery of the global marine ecosystem-measured as primary productivity-was geographically heterogeneous 8 ; export production in the Gulf of Mexico and North Atlantic-western Tethys was slower than in most other regions8-11, taking 300 thousand years (kyr) to return to levels similar to those of the Late Cretaceous period. Delayed recovery of marine productivity closer to the crater implies an impact-related environmental control, such as toxic metal poisoning 12 , on recovery times. If no such geographic pattern exists, the best explanation for the observed heterogeneity is a combination of ecological factors-trophic interactions 13 , species incumbency and competitive exclusion by opportunists 14 -and 'chance'8,15,16. The question of whether the post-impact recovery of marine productivity was delayed closer to the crater has a bearing on the predictability of future patterns of recovery in anthropogenically perturbed ecosystems. If there is a relationship between the distance from the impact and the recovery of marine productivity, we would expect recovery rates to be slowest in the crater itself. Here we present a record of foraminifera, calcareous nannoplankton, trace fossils and elemental abundance data from within the Chicxulub crater, dated to approximately the first 200 kyr of the Palaeocene. We show that life reappeared in the basin just years after the impact and a high-productivity ecosystem was established within 30 kyr, which indicates that proximity to the impact did not delay recovery and that there was therefore no impact-related environmental control on recovery. Ecological processes probably controlled the recovery of productivity after the Cretaceous/Palaeogene mass extinction and are therefore likely to be important for the response of the ocean ecosystem to other rapid extinction events.
Rising oceanic and atmospheric oxygen levels through time have been crucial to enhanced habitability of surface Earth environments. Few redox proxies can track secular variations in dissolved oxygen concentrations ([O2]) around threshold levels for metazoan survival in the upper ocean. We present an extensive compilation of iodine to calcium ratios (I/Ca) in marine carbonates. Our record supports a major rise in atmospheric pO2 at ~400 million years ago (Ma), and reveals a step-change in the oxygenation of the upper ocean to relatively sustainable near-modern conditions at ~200 Ma. An Earth system model demonstrates that a shift in organic matter remineralization to greater depths, which may have been due to increasing size and biomineralization of eukaryotic plankton, likely drove the I/Ca signals at ~200 Ma.
Shuang Dai
added an update
Photo 1 Siliceous nodules in limestone.
Photo 2 suture line.
 
David De Vleeschouwer
added 2 research items
The Wetteldorf section is the Global Stratotype Section and Point (GSSP) locality of the Lower- Middle Devonian boundary. The section is characterized by an alternation of marls, limestones, and siltstones, with the base of the Eifelian stage defined by the first occurrence of the conodont Polygnathus costatus partitus. The well-established conodont biostratigraphy for this section permits correlations with other time-equivalent sections; however, a cyclostratigraphic framework does not yet exist for this section. Here, we construct such a framework that provides an additional tool for long-distance correlation, and at the same time constrains the amount of geologic time represented by this stratigraphic interval. Microfacies analysis indicates that the entire section has been deposited in an open-marine shelf paleoenvironment, below the storm wave base and under oxygen-rich conditions. We collected high-resolution (5-cm spaced) geochemical data, using a handheld X-ray fluorescence (XRF) spectrometer, and quantified net intensity results for 23 chemical elements. By using factor analysis, we explain 52% of the observed variance in those elements by a model that consists of four factors. The most important factor, factor 1, is driven by geochemical elements related to detrital input (e. g. K, Rb, Si, Ti). Factor 2 is interpreted as a pyrite-indicator, while Factor 3 is driven by Ca and Sr and is thus tied to lithological variations in carbonate content. Factor 1 and 3 are used for cyclo - stratigraphy, as their respective power spectra show similar characteristics. Both factors exhibit a strong 58-cm period, which can be interpreted, according to the available biostratigraphic constraints, either as the imprint of the 18-kyr precession cycle or as the imprint of the 33-kyr obliquity cycle. However, the ratio between different spectral peaks in the different proxies' power spectra strongly advocates the first option. Our interpretation in terms of astronomical climate forcing implies that the 8.65 meter thick Wetteldorf section (within the Happel Hut) is characterized by an average sedimentation rate of ~ 3.2 cm/kyr and represents ~ 250 kyr. From a paleoclimatological point of view, our results indicate that detrital input into the Rhenohercynian Basin was spurred under high-eccentricity configurations, which allowed for strongly enhanced seasonal rainfall. Under astronomical configurations that avoided extremes in seasonality for a prolonged period of time (simultaneously low eccentricity and obliquity), Factor 2 indicates the occurrence of pyrite, which we associate with temporary deteriorations of generally well-oxygenated conditions.
The Late Devonian envelops one of Earth’s big five mass extinction events at the Frasnian–Famennian boundary (374 Ma). Environmental change across the extinction severely affected Devonian reef-builders, besides many other forms of marine life. Yet, cause-and-effect chains leading to the extinction remain poorly constrained as Late Devonian stratigraphy is poorly resolved, compared to younger cataclysmic intervals. In this study we present a global orbitally calibrated chronology across this momentous interval, applying cyclostratigraphic techniques. Our timescale stipulates that 600 kyr separate the lower and upper Kellwasser positive δ13C excursions. The latter excursion is paced by obliquity and is therein similar to Mesozoic intervals of environmental upheaval, like the Cretaceous Ocean-Anoxic-Event-2 (OAE-2). This obliquity signature implies coincidence with a minimum of the 2.4 Myr eccentricity cycle, during which obliquity prevails over precession, and highlights the decisive role of astronomically forced “Milankovitch” climate change in timing and pacing the Late Devonian mass extinction.
Michael T. Whalen
added 3 research items
The International Geoscience Program project IGCP- 580 (started in 2009), focuses on the application of magnetic susceptibility (MS) as a paleoclimatic proxy on Paleozoic sedimentary rocks and on the characterization of the magnetic susceptibility signal. Here we provide a summary of the scientific targets behind the project and a summary of the organized activities. This project concerns three main issues: the first one consists of compiling the available MS data from the different researchers and continuing the collection of new data (with a main focus on the Devonian). The second issue focuses on the identification of the nature and origin of the magnetic minerals carrying MS signal. The last issue concerns the application of MS as a correlation, cyclostratigraphic and paleoclimatic tool. The IGCP-580 community consists of 245 researchers, from 45 countries (including Kenya, Namibia, Vietnam, Iran, Uzbekistan, Algeria, Tunisia, Colombia, Nigeria, India, etc.). During the project, we organized five meetings (Belgium, China, Czech Republic, Austria, Canada), three special sessions in international meetings and eight field workshops, as well as various training sessions. © 2014. International Union of Geological Sciences. All rights reserved.
We investigate the Late Devonian Frasnian-Famennian extinction interval in western Alberta and south China to shed light on the palaeoecological and palaeoceanographic conditions that characterize this biotic crisis. Both the Lower and Upper Kellwasser events are documented in western Canada. Only the Upper Kellwasser event has been evaluated in south China. Our multiproxy geochemical approach reveals that these events are characterized by positive δ13C and δ15N excursions and increasing magnetic susceptibility (Canada/China) and increases in detrital (Al, Si, Ti, Zr), productivity (Cu, Ni, Zn) and redox (Mo, U, V) elemental proxies (Canada). We interpret these trends as part of a systemic palaeoecological shift associated with the development of widespread terrestrial forests and their alteration of chemical-mechanical weathering patterns. Increase in detrital proxies is thus interpreted as resulting from pedogenically driven weathering on the continents that nutrified epeiric and continental margin seas. High biological productivity led to eutrophication and development of suboxic to anoxic conditions during both events and probably euxinic conditions during the Upper Kellwasser event in western Canada. Positive δ13C excursions are the telltale signature of excessive carbon burial, while redox proxies and δ15N records indicate suboxic-anoxic denitrifying conditions.
Upper Devonian rocks in western Canada were deposited as carbonate-platform and surrounding slope and basinal rocks during a second-order sea-level cycle, characterized by long-term climatic warming, that ended with cooling associated with the Frasnian–Famennian mass-extinction event. In this contribution, we assess the hypothesis that high-resolution magnetic susceptibility (MS) data records cross-basin variations that are intimately tied to sea level and associated climatic change, the depositional environment, and the paleogeographic location of siliciclastic sediment sources. Four main trends are apparent in the MS data: (1) the magnitude of the MS signature increases from west to east across western Canada; (2) platform facies generally have low MS signatures compared with off-platform facies; (3) the overall MS signature increases and then decreases throughout the stratigraphic profile, largely in response to changes in depositional setting (i.e., item 2); (4) MS is generally high during third-and fourth-order sea-level lowstand and early transgression and lower during late transgression and highstand. During the late Middle (Givetian) to early Late (Frasnian) Devonian, siliciclastic sediments (silt and fine sand size) sourced from the west Alberta arch and Peace River arch, contributed to relatively high MS signatures in facies deposited proximal to these source areas. Other important detrital sediment sources were the Ellesmerian orogenic belt in northern Canada and the Laurussian continental landmass to the east. These latter sources supplied fine-grained sediments that were dispersed basin-wide and resulted in a nearly order-of-magnitude increase in MS values to the east. This trend and fine grain size implies that some detrital sediment was delivered from the east as eolian dust from the ''Old Red Continent.'' By the early Frasnian, the west Alberta arch was submerged, and by middle to late Frasnian time the Peace River arch was largely covered. During the late middle Frasnian a pronounced rise in MS signatures can be tied directly to deposition of the clay-and locally silt-rich Mount Hawk Formation. During the late middle to late Frasnian, carbonate-ramp facies prograded from east to west, resulting in seaward migration of the shoreline and increased siliciclastic input to the ramp slope that influenced the pronounced increase in MS signatures to the east. By the late Frasnian, cross-basin MS profiles record uniformly low susceptibilities indicating that high MS siliciclastic detritus was either bypassed seaward, was swamped by carbonate input, or was dominated by diamagnetic quartz. Individual MS events can be accurately correlated across much of the basin at a resolution that is higher than single conodont zones despite the local influences on variability of the signature. Variations in the MS signature can thus be explained partly by depositional environment (platforms with low MS, basins with higher MS) and partly by third-and fourth-order sea-level and associated climatic changes. Fourth-order changes in sea level are routinely interpreted to result from variations in paleoclimate in the Milankovitch band and recent work indicates that third-order sea-level changes may be linked to longer-term modulation of Milankovitch-band orbital variations. The increase in MS during prolonged Frasnian warming thus appears to be directly linked to paleoclimatic change, and comparison of the MS signature with more direct measures, like oxygen isotopes, would serve as a test of its utility as a paleoclimate proxy.
David De Vleeschouwer
added an update
Don't forget to submit an abstract on your latest work to our special session during the International Meeting of Sedimentology in Toulouse! Our session is titled "Reading geological Time - Climate and Cyclostratigraphy".
The deadline has been extended to June 19th, so a bit less than a week to get your abstract into the system.
Good luck & see you there!
 
Shuang Dai
added an update
Project goal
Major events punctuated the Paleozoic: ecological crises and diversifications, shifts in ocean chemistry, climatic changes, etc. One of the key-obstacles in understanding these events lays in the difficulty of providing precise estimates of the duration represented by a sequence of Paleozoic sedimentary rocks. This lack of temporal precision severely hampers the evaluation of forcing mechanisms and rates of climatic, ecological or biogeochemical changes in the Paleozoic. It is therefore essential to first improve the Paleozoic timescale to then unravel the history of the Paleozoic Earth system.
Cyclostratigraphy is a powerful chronometer, based on the detection of the Milankovitch cycles in the sedimentary record. Those cycles result from periodic variations in the Earth-Sun system, affecting the distribution of solar energy over the Planet influencing Earth’s climate on time scales between 104 and 106 years. Through the integration of this astronomical time scale with biostratigraphy and radio-isotopic dating, this project intends to document the environmental evolution during the Paleozoic with a focus on the Ordovician to Devonian (485 – 359 million years). It gathers participants (> 200) from all over the world (36 countries) and promotes the participation of young scientists and scientists from developing countries.
Background and motivation
The Palaeozoic is a very important Era for the Earth’s tectonic evolution and environmental changes. However, our understandings of this process are hampered by the low temporal resolution of the timescale, and the lack of more reasonable correlation of the tectonic and climatic events in global scale. Thus, the main aim of this project are: (1) Building a high resolution database of various proxies focussing on Ordovician to Devonian intervals; (2) Improving the Palaeozoic time scale and (3) shedding new light on the different Palaeozoic events. This will provide a better-calibrated Ordovician to Silurian time scale and new insight into biological evolution, climate changes and a better understanding of how Earth evolved.
The main results of this project are firstly to be expected in the elaboration of a proxy database, which will make significant improvement of the Palaeozoic time scale, and the comprehension of the Palaeozoic climatic system. These will have an influence on a lot of Palaeozoic researchers, implying a large impact of the project. Secondly, new methodology or software developed during the project will improve correlations of global or local climatic events, which can be used to better understand the formation of oil and gas in the worldwide. Thirdly, this project is benefit to society. By publishing the research’s results on the journal or advertisement on the project’s website, etc., the society will understand the potential controls, especially on relatively rapid climate events. This could provide insight into the outcomes of current anthropogenic-induced warming. Furthermore, through international collaboration, annual meetings, workshops and post-meeting fieldtrips, the project will definitely enhance the training of graduate students and young scientists in the participating countries, as well as enhance social understanding, knowledge transfer, technological advancement and international cooperation among developed and developing countries.
 
David De Vleeschouwer
added a project goal
Major events punctuated the Paleozoic: ecological crises and diversifications, shifts in ocean chemistry, climatic changes, etc. One of the key-obstacles in understanding these events lays in the difficulty of providing precise estimates of the duration represented by a sequence of Paleozoic sedimentary rocks. This lack of temporal precision severely hampers the evaluation of forcing mechanisms and rates of climatic, ecological or biogeochemical changes in the Paleozoic. It is therefore essential to first improve the Paleozoic timescale to then unravel the history of the Paleozoic Earth system.
Cyclostratigraphy is a powerful chronometer, based on the detection of the Milankovitch cycles in the sedimentary record. Those cycles result from periodic variations in the Earth-Sun system, affecting the distribution of solar energy over the Planet influencing Earth’s climate on time scales between 104 and 106 years. Through the integration of this astronomical time scale with biostratigraphy and radio-isotopic dating, this project intends to document the environmental evolution during the Paleozoic with a focus on the Ordovician to Devonian (485 – 359 million years). It gathers participants (> 200) from all over the world (36 countries) and promotes the participation of young scientists and scientists from developing countries.