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Introduction
Publications
Publications (224)
Lateral facies heterogeneity and carbonate production perturbation within peri-Tethyan platforms were widespread phenomena during the Early Jurassic. These variations were either controlled by local factors affecting small areas or by processes prevailing on a global scale. Three geological sections are investigated in Lower Jurassic outcrops in th...
Carbonate sedimentary rocks are crucial for understanding Earth's geological history, ecosystems, and climate dynamics. However, their study is complicated by diagenetic processes that can alter original bedding and surfaces, leading to potential misinterpretations, for example of palaeoecological and sedimentological settings as well as the time r...
Bedding and bedding surfaces in carbonate and mixed siliciclastic-carbonate successions can be diagenetic, not depositional in origin and require interrogation to determine their true origins. This study reviews the different models and implications associated with diagenetic bedding and diagenetic bedding surfaces in such successions. Weathering,...
Artificially cemented sandstones were produced to assess the impact of detrital texture and composition on the precipitation and distribution of early calcite cement, and cement-related degradation in porosity. To simulate early-calcite cementation, loose sediment of variable composition (siliciclastic and calcareous) and grain size was exposed to...
Climatically the Silurian was a most unstable period, as it is shows several strong δ ¹³ C excursions, with the Lau excursion being the strongest short-lived positive δ ¹³ C excursion of the entire Phanerozoic. The causes of these excursions remain a topic of debate. In order to determine how benthic communities responded to these climatic perturba...
Early micritic cementation is important to reconstruct paleoenvironments of sedimentary gaps. However, due to their scarcity in ancient records, their initial mineralogy (low-magnesium calcite (LMC), high-magnesium calcite (HMC), aragonite), as well as their origin (biotic or abiotic) and paleoenvironments are still controversial. Herein, based on...
The Xiangshuyuan Formation (middle Rhuddanian to middle Aeronian stages of the Llandovery Series, lower Silurian) records a shelly fauna representing recovery after the end-Ordovician mass extinction in a well-oxygenated shallow carbonate platform of the Upper Yangtze region, South China Block. Carbon isotope stratigraphy is documented from limesto...
The platycerate gastropods Orthonychia yutaroi Ebbestad, sp. nov. (Ordovician, Boda Limestone, Sweden), O. enorme (Silurian, Sweden, Gotland), O. parva (Pennsylvanian, Finis Shale Member, USA), and Orthonychia sp. (Mississippian, Imo Formation, USA) are studied including their protoconch morphology. Orthonychia yutaroi is the oldest known species i...
The picture stones from Gotland are one of the most famous and exceptional groups of monuments known from Swedish Prehistory. These carved memorial stones and their extraordinarily rich imagery are a unique source for the study of Late Iron and Viking Age culture and in particular Scandinavian
pre-Christian religions. The Gotlandic picture stones a...
Sandstones with carbonate cements are found in a variety of depositional settings (e.g. fluvial, lacustrine, deltaic, shallow marine) with abundances ranging from just a few volume percent to pervasive pore-filling cements and are of major interest due to their impact on reservoir quality. Despite the widespread occurrence of such cements, predicti...
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Understanding ancient climate changes is hampered by the inability to disentangle trends in continental ice volume from records of relative sea-level change. As a unique coastal deposit in tropical and subtropical regions, beachrock has been proved to be reliable for constraining the glacial meltwater signal and thus the total volume of land-based...
The Pliensbachian–Toarcian transition was characterised by a drastic turnover from a cool climate to a period of rapid
global warming. While the warming associated with the Early Toarcian Oceanic Anoxic Event is rather well-studied, the
cause, intensity and extent of the preceding cooling in the late Pliensbachian are still discussed. Occurrences...
Reports of diverse vermiform and peloidal structures in Neoproterozoic to Mesozoic open marine to peritidal carbonates include cases interpreted to be keratose sponges. However, living keratose sponges have elaborate, highly elastic skeletons of spongin (a mesoscopic end‐member of a hierarchical assemblage of collagenous structures) lacking spicule...
A unique occurrence of ironstone lenses represented by ferruginous oncoids is reported from the offshore Řeporyje Limestone (Lower Devonian, Pragian) from the Prague Basin (the Stydlé Vody Quarry). The oncoidal cortices show distinct arrangement of hematite/chamosite and/or iron-bearing calcite laminae, which are irregular, wavy and with a relative...
Understanding the causes of the formation of hardgrounds provides insights on the oceanographic evolution of a basin. Phosphate-rich hardground formation interrupted carbonate ramp deposition in the Mediterranean during the Miocene. We analyzed the εNd record of three central Mediterranean hardgrounds to identify the origin of the phosphate-rich wa...
The Late Jurassic is considered as greenhouse period. Most palaeoclimatic data, however, have been derived from European basins, and these data show an increase of the palaeotemperature from the Oxfordian to the Tithonian. In the present study we for the first time present such data from the Ouarsenis Mountains, northwest of Algeria (southern margi...
The order Heterocorallia is an enigmatic, anatomically distinct group of calcifying Palaeozoic corals with unclear affinities to other, either extinct or modern cnidarian lineages. Here, we present results of microstructure and stable isotope studies on exceptionally well-preserved skeletons of two species of the heterocoral Oligophylloides from th...
The Ordovician (∼487 to 443 Ma) ended with the formation of extensive Southern Hemisphere ice sheets, known as the Hirnantian glaciation, and the second largest mass extinction in Earth History. It was followed by the Silurian (∼443 to 419 Ma), one of the most climatically unstable periods of the Phanerozoic as evidenced by several large scale (>5‰...
Foraminiferal zonation based on cosmopolitan taxa is poorly defined in the Viséan–Serpukhovian boundary interval in South China, hampering regional/global stratigraphical correlations and, to some extent, weakening the competitiveness for the Serpukhovian Global Stratigraphical Section and Point (GSSP). To address this issue, we investigated forami...
The algal genus Vitinellopsis nov. gen. is well represented in the Silurian limestones of Gotland (Sweden). This new taxon is interpreted as a calcified codiacean alga (Chlorophyta, Bryopsidales). In the studied material, the calcareous wall of sparry calcite, probably originally aragonitic, appears well preserved. The subcylindrical thallus, with...
Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this stu...
Evaluating shell preservation of Campanian rudists (Macgillavryia sp., Vaccinites sp., Torreites sanchezi) by investigating their microstructure and mineral composition, allows tackling the development of silica replacement as a crucial diagenetic feature prior to sclerochronological and geochemical analyses. Understanding the silicification spatia...
The palaeogeographic position of the Saharan Central Atlas was on the western margin of the Tethys in an epicontinental shallow area between a continental domain in the west and a deeper oceanic domain in the east. The Late Jurassic is a time of pronounced climate perturbations, and in the studied area in Algeria several carbonate platforms develop...
Bryostromatolites are found in stressed environments from the Paleozoic to the Recent. They are formed by alternating layers of bryozoans and microbes. This study investigates recent bryostromatolites in brackish ponds in the Netherlands to better understand ancient analogues and the environments which hosted them. They formed a fringing reef at th...
The Ordovician Chiatsun Group, exposed at the Jiacun section, Nyalam, in southern Xizang (Tibet), China, is biostratigraphically one of the best constrained Ordovician sections in the Himalaya margin, and thus plays a key role in correlating the Ordovician strata of this region. The Chiatsun Group is subdivided into the Adang Formation, the Alai Fo...
Palaeozoic stromatoporoids, throughout their 100-million + year history (Middle Ordovician to Late Devonian and rare Carboniferous), are better preserved than originally aragonite molluscs, but less well-preserved than low magnesium calcite brachiopods, bryozoans, trilobites and corals. However, the original mineralogy of stromatoporoids remains un...
Investigation of large populations of peteinoid acritarchs recovered from Middle Ordovician strata of the Hälludden and Horns Udde quarry sections (Öland, Sweden) allows for statistical analyses based on morphometric measurements. The results indicate the presence of assemblages with a continuous variability of morphotypes, thus a distinction of di...
Stable carbon isotope curves are used as a precise stratigraphic tool in the Paleozoic, even though they are commonly based on shallow-water carbonate record, characterized by low stratigraphic completeness. Identification of episodes of large-scale redeposition and erosion may improve δ13Ccarb-based correlations. Here, a series of at least three e...
Bryozoan–stromatolite associations (bryostromatolites) formed conspicuous reef structures throughout the Sheinwoodian (Wenlock) to Ludfordian (Ludlow) stratigraphy on Gotland but have not been described so far. They are mainly composed of encrusting bryozoans forming a complex intergrowth with porostromate and spongiostromate microbes and are diffe...
Methane seepage along continental margins has been linked to climatic warming, yet it is uncertain whether such seepage took place during the Permian, a period that witnessed a transition from an icehouse to a greenhouse world. To address this issue, we investigated calcareous concretions and layers within mudstones/shales of the Kungurian Angie Fo...
The Upper Jurassic rocks of the El Bayadh Area (Central Saharan Atlas, Algeria) are composed of mixed siliciclastic-carbonate rocks, which were roughly assigned to a Kimmeridgian-Hauterivian age in previous studies. Based on our studies, the succession can be subdivided into five new formations; from base to top: the Theniet Et-Temar, Ksel, Lagurem...
This study presents the first record of stable carbon and oxygen isotopes of well-preserved belemnites and bulk sediment from the Upper Jurassic pelagic carbonates of the Ouarsenis Mountains (northwestern Algeria), which were deposited at the southern margin of the Tethys ocean. Cathodoluminescence and scanning electron microscopy was used to elimi...
Variations in depositional rates affect the temporal depositional resolutions of proxies used for paleoenvironmental reconstructions; for example, condensation can make reconstructed environmental changes appear very abrupt. This is commonly addressed by transforming proxy data using age models, but this approach is limited to situations where nume...
The Calcarenite di Gravina is a poorly lithified, heterogeneous bio-lithoclastic Plio-Pleistocene limestone formed in a temperate shallow-water setting. Since prehistoric times it has been used for construction, as witnessed by the “Sassi”, the old city center of Matera (southern Italy). Here, the relatively distal, fine-grained bioclastic grainpac...
The origin of limestone–marl alternations (LMA) and their diagenesis is still lively debated. The most disputed question is whether original variations in sediment input control the differentiation of the precursor sediment into limestone and marl, or if a LMA can form without compositional differences in the precursor sediment. The Miocene brackis...
Methane seepage along continental margins has been linked to climatic warming, yet it is uncertain whether such seepage took place during the Permian, a period that witnessed a transition from an icehouse to a greenhouse world. To address this issue, we investigated calcareous concretions and layers within mudstones/shales of the Kungurian Angie Fo...
Eight bryozoan species are described from the Hanchiatien Formation (lower Silurian, Telychian) of southern Chongqing, South China. Four species are new: the trepostomes Asperopora sinensis n. sp., Trematopora jiebeiensis n. sp., and Trematopora tenuis n. sp., and the fenestrate Moorephylloporina parvula n. sp. One species, the cystoporate Hennigop...
The late Miocene is a crucial interval for global climate evolution as well as for the regional geodynamic evolution of the Central Mediterranean area. It spans the transition
from the warm Mid Miocene Climatic Optimum, associated with the major Monterey
Carbon Isotope Excursion, to the cooler Pliocene, characterized by a bipolar
glaciation. Within...
Trophic interactions of extinct fishes are central to our understanding of evolution, paleoecology, and their role in the paleo-communities, but can be challenging, as these are limited by the incompleteness of the fossil record and by a lack of behavioural data. The extensive fossil record of Actinopterygii comes mostly from Conservation-Lagerstät...
Bivalves document their response to environmental and climatic changes in their shells. Each individual species has different growth rates and life-strategies, which are reflected in their morphology, incremental banding and geochemical shell composition. During the Late Cretaceous rudist bivalves became diverse and very abundant thus their shells...
The Late Ordovician succession of the Baltic Basin contains a characteristic fine-grained limestone, which is rich in calcareous green algae. This limestone occurs in surface outcrops and drill-cores in an extensive belt reaching from Sweden across the Baltic Sea to the Baltic countries. This limestone, which is known in the literature under severa...
The Sassi of Matera, UNESCO site since 1993, represents a human settlement completely integrated in the natural landscape. There, the development of the community is closely connected to the geology since prehistoric times. The Calcarenite di Gravina, a Pleistocene poorly lithified limestone onlapping a large area of the Apulian foreland in souther...
New δ13Ccarb and microfacies data from Hereford–Worcestershire and the West Midlands allow for a detailed examination of variations in the Homerian carbon isotope excursion (Silurian) and depositional environment within the Much Wenlock Limestone Formation of the Midland Platform (Avalonia), UK. These comparisons have been aided by a detailed seque...
Matera (Basilicata, southern Italy) was awarded World Heritage Site status by the UNESCO since 1993, and it will be the European Capital of Culture in 2019. It is one of the most ancient towns in the world, whose historical centre was totally built by only a moderately lithified and highly porous sedimentary building stone, known as Gravina Calcare...
Limestone-marl alternations are often interpreted to reflect cyclic changes in the depositional environment, with time spans for the deposition of a limestone-marl couplet between thousands and tens of thousands of years. Data from halysitid coral colonies from Gotland (Silurian), Sweden, indicate a diagenetic origin of limestones and marls indiffe...
Meter-scale shallowing-upward cycles are recorded in many carbonate successions around the world. It is often difficult to recognize whether they represent autocycles, formed through intrinsic controls, or allocycles, resulting from orbital forcing or tectonic movements, or both. Here, we review the criteria used in the identification of the two ty...
Compared to modern counterparts, bioerosion is rare in Paleozoic reefs, especially macro-bioerosion. The unique and enigmatic Silurian reefs from Gotland (Sweden), composed of bryozoans and microbial laminates, show evidence of a large amount of bioerosion. The samples contain Trypanites trace fossils, as well as a large number of undescribed macro...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Carbonate concretions have been recorded in many recent and ancient marine sediments around the world. The Middle Miocene marl of the Tenes area, situated in the northeast of the Lower Chelif Basin in NW-Algeria, contains such carbonate concretions but with a variety of different structures and morphologies. Three different basic types are distingu...
Asymmetric, pendant cements are considered good indicators for early lithification in the vadose zone. In the present study, asymmetric cements are recorded in thin-sections of a Lower Jurassic limestone from the Traras Mountains (northwest Algeria). Geopetal fabrics, however, indicate that these seemingly “pendant cements” are, in some places, ori...
Asymmetric, pendant cements are considered good indicators for early lithification in the vadose zone. In the present study, asymmetric cements are recorded in thin-sections of a Lower Jurassic limestone from the Traras Mountains (northwest Algeria). Geopetal fabrics, however, indicate that these seemingly “pendant cements” are, in some places, ori...
Aguirrea fluegelii gen. et sp. nov. (Corallinales, Corallinophycidae, Rhodophyta) is described from the mid‐Silurian of Gotland Island, Sweden (Högklint Formation, lower Wenlock). The holotype is of dimerous construction and includes a uniporate conceptacle with a sporangium, thus providing evidence that taxa of the Corallinales/Corallinaceae exist...
Summary: Stone monuments represent important and diversified cultural heritages of different ages, spread all around the world. The rocks, however, are altered by a set of physical and chemical reactions occurring at the intersection of the lithosphere, atmos- phere, hydrosphere, and biosphere. The degree of alteration is related to the chemical an...
Sandstone and carbonate concretions in the middle Miocene rocks in Tenes area (Lower Chelif Basin, Nord-West Algeria): anatomy and origin.
PPendant cements, i.e. asymmetric precipitated crusts, concentrated on the undersides of grains are thought to be limited to the vadose zone (marine or meteoric), where water driven by gravitational drainage has filled pores only periodically and partially.Such asymmetric cements have been recorded in thin sections from the Ras El Manara section (Z...
The classification of acritarchs remains a major problem concerning the study of this group, which is considered as representing a major part of the organic-walled phytoplankton of the Palaeozoic. It can be assumed that a large part of the taxa described in literature are not real biological entities but rather represent different (eco-) phenotypes...
Based on the aragonite composition of extant cephalopods and exceptionally preserved fossil cephalopods going back to the Paleozoic, it is commonly assumed that externally shelled cephalopods had an aragonitic shell wall. We present evidence that at least two lineages of orthoconic nautiloids in the Silurian and Devonian calcite seas were originall...
Stromatoporoids were abundant components of reefs, reef complexes and associated facies for ca. 100 million years between Middle Ordovician and end-Devonian time. A lot of environmental information stored in their skeletons may be used to develop: a) understanding of stromatoporoid growth controls; and b) interpretations of sedimentary environments...
