T05 Theme 5: Stratigraphic archives of evolution of climate, oceans, and biota
T05-SS01 – Paleozoic ocean, lands, ecosystems and climate imprinted in sedimentary strata: New insights from high-resolution proxies
Conveners: Kabanov P. (Geological Survey of Canada, NRCan, Canada), da Silva A. C. (Université du Liége, Belgium)
The sedimentary record unveils a lot of previously unknown due to instrumental innovations augmenting conventional observations to ever increasing degree, elemental and isotope geochemistry, magnetic susceptibility are just a few out of many groups of methods enhancing our capacity to read signals coded in sedimentary strata, and advancing geochronology is paving the way to globewide synchronization of events and cyclic sedimentary processes of the Past. Palaeozoic stratal archive still bears a lot of knowledge gaps and controversies. The need to better understand Palaeozoic strata emerges not only from their economic value, but they also imprint icehouse-greenhouse transitions and prominent events of biotic crises and rapid climate change. This session is open to research of Palaeozoic sedimentary strata in all forms: marine and non-marine sediments, cyclic stratal successions of various expressions, stratigraphic unconformities and paleosols, the widest range of conventional observations, petrography, instrumental proxies, and modelling as applied to better understanding of the dynamics of oceans, seas, lands, and climates of the deep Past. This session equally welcomes talks on biotic imprints in Palaeozoic sediments.
T05-SS02 – Climatic, environmental, and biotic crises of the Permo- Triassic: Sedimentary records of the transition to the Mesozoic world
Conveners: Frank T. (University of Nebraska–Lincoln, USA), Fielding C. (University of Nebraska–Lincoln, USA), Bourquin S. (French National Centre for Scientific Research, France)
The Permian and Triassic periods witnessed Earth’s penultimate icehouse, the development of extreme hothouse conditions, and the largest extinction event of the Phanerozoic. The late Paleozoic Icehouse was the longest and most intense glaciation of the Phanerozoic, with atmospheric composition that encompassed both the lowest carbon dioxide and highest oxygen levels of the Phanerozoic. Fundamental shifts in atmospheric circulation led to the development of a global megamonsoon. Arid tropical late Permian environments in America were balanced by environments elsewhere that supported extensive peat accumulation. The transition to the Triassic was marked by a complex ecological catastrophe, with volatile release from basaltic magma and sedimentary strata contributing to greenhouse gas-induced extreme global warming and widespread anoxia and acidification contributing to the extinction of about 96 percent of all species. In light of conditions comparable to those anticipated for Earth’s immediate future, there is an urgent need to assess this dynamic time period in a variety of settings and over a longer timeframe using integrated datasets. This session aims to explore the latest results of research on Permian and Triassic climate and environment in a range of marine and terrestrial settings.
T05-SS03 – Understanding a greenhouse Earth: Climate, sea level, ocean circulation and biogeochemical cycles in the Cretaceous
Conveners: Uličný D. (Institute of Geophysics, Prague), Batenburg S. (Université Rennes, France)
Intervals of geological history characterized by a greenhouse climate regime serve as a source of important data for understanding climatic processes in the past as well as in the near future. The Cretaceous Period was characterized by a greenhouse climate involving polar warmth, a Phanerozoic maximum in sea level, exotic thermohaline circulation patterns in oceans, and global perturbations of the carbon cycle expressed in oceanic anoxic events. During the past two decades, evidence for short-term sea-level changes has fueled debate about controversial short-lived glacial episodes in this greenhouse world. Most recently, aquifer-eustasy or limno-eustasy are being increasingly invoked as possible drivers of greenhouse sea-level change. New and higher-resolution datasets and new modelling efforts (including use of GCMs) are needed in order to improve our understanding of relationships between the greenhouse climate, ocean behaviour, and global biogeochemical cycles, on time scales approaching those of younger sedimentary archives of the Cenozoic. This session aims to present current work on the above topics, focusing particularly on high-resolution and multi-disciplinary studies, integrating the approaches of sedimentology, palaeontology, mineralogy, geochemistry, sequence stratigraphy, chemo- and cyclostratigraphy, and numerical modelling.
T05-SS04 – Black shales: Past depositional systems and modern environments
Conveners: Gambacorta G. (Eni, Italy), Frijia G. (University of Ferrara, Italy), Parente M. (University of Naples Federico II, Italy), Wignall P. (University of Leeds, UK)
Decades of research have clearly shown that is not always possible to apply uniformitarian principles to depositional models for black shales. Enhanced preservation in stratified landlocked or silled basins and enhanced productivity in coastal upwelling
zones represent two modern end-members that do not always capture the variety and complexity of processes that acted during peculiar time interval in Earth history. Consequently, ancient black shales represent unique and fundamental archives of peculiar processes not directly observable in modern environments. On the other hand, modern depositional settings offer a unique opportunity for directly observing and measuring the relative importance of sedimentary style, primary productivity, water-column and sediment anoxia in controlling the vertical and lateral distribution of organic carbon-rich sediments. The study of recent depositional models for ancient black shales and modern organic carbon-rich sediments is increasingly capturing the complexity and variability of processes involved in their deposition. However, further careful and multidisciplinary studies of ancient and modern records are needed to better understand the local and global factors that drove organic matter accumulation in the geological record. The aim of this session is to provide a representative review of the state of the art of black shale petrography, sedimentology and stratigraphy. Contributions to this session should reflect the current views of black shale deposition and environments from modern and past continental and marine sedimentary records.
T05-SS05 – Sedimentary environments as the theatres of life and evolution
Conveners: Shillito A. (University of Oxford, UK), Davies N. (University of Cambridge, UK), McMahon W. (Utrecht University, the Netherlands), Rice S. (Loughborough University, UK)
The sedimentary record provides an archive of ancient environments, intrinsic to which were organisms that evolved and adapted throughout Earth history. Life and environment have co-evolved throughout geological time, as organisms have sculpted and influenced physical landforms, bedforms and sedimentary processes. The objectives of this session are (1) to recognise what information of major Earth-historical evolutionary innovations and extinction events is archived within the ancient sedimentary record; (2) to unravel sedimentary clues pertaining to the influence of physical environments on ancient organisms; and (3) to improve understanding of how the fossil record and physical sedimentary record co-evolved as the biosphere became an increasingly significant component of the geosphere. Contributions are welcome from work at all scales of these objectives, from fields including ichnology, sedimentary geology, geochemistry, geomorphology, and palaeoecology, in both marine and non-marine settings.
T05-SS06 – Continent-ocean interactions and their geological records: A tribute to Karl Föllmi
Conveners: Adatte T. (Lausanne University, Switzerland), Bomou B. (Lausanne University, Switzerland), Bodin S. (Arrhus University, Denmark), Fantasia A. (Arrhus University, Denmark), Van de Schootbrugge B. (Utrecht University, the Netherlands)
With the recent passing of Karl Föllmi, sedimentology and Earth Science in general lost a scientist of international reputation. This session will be focused on continent-ocean interactions and their geological records, in particular in Mesozoic shallow water carbonates, one of the favourite research topics of Karl Föllmi.
T05-SS07 (new for 2021) – Western Tethys meets Eastern Tethys – sedimetological perspective
Conveners: Krobicki M. (AGH University of Science and Technology, Poland), Gawlick H.-J. (Montanuniversitaet Leoben, Austria), Goričan Š. (Research Centre of the Slovenian Academy of Sciences and Arts, Slovenia), Huang H. (Chinese Academy of Geological Sciences, China), Ueno K. (Fukuoka University, Japan), Yilmaz İ. Ö. (Middle East Technical University, Turkey), Kowal-Kasprzyk J. (AGH University of Science and Technology, Poland), Starzec K. (AGH University of Science and Technology, Poland)
The geological history of the Tethys Ocean is broadly established. However, many details are still unknown and many major questions related to geotectonics, palaeogeography, palaeoceanography and palaeobiogeography remain unanswered. Improved understanding of Mesozoic-Cenozoic ocean/climate history is based on accurate reconstruction of distribution of continents and ocean basins and on reconstruction of opening and closing of seaways along the Tethys. There is little or no agreement about the number or size of separate basins neither on their space-time relationships. Moreover, there is no consensus on the number and location of former micro-continents and on their incorporation into the present-day Eurasian-Mountain Belt. In addition, diachronic closure or collision of continent/continent lets along the margin of Tethys Ocean will also be highlighted by details studies. Correlation between Western and Eastern Tethys is difficult not only because of the large distances involved but also because they are separated by the area of the huge Himalayan collision within which much of the pre-Palaeogene tectonostratigraphic information has been lost. Regarding the above discussions and controversies the IAS’s Special Session will focus on the sedimentological comparison between the Western and Eastern part of the Tethys (Morocco/Iberia–SE Asia) during the latest Paleozoic–Mesozoic times including reconstruction of palaeoceanographic conditions recorded in sedimentary structures and fossils.
T05-SS08 – Diagenetic signals in the sedimentary record of environmental change
Conveners: Nohl T. (Geozentrum Nordbayern, Germany), Reuning L. (Kiel University, Germany), De Vleeschouwer D. (Universität Bremen, Germany), Wright V. P. (National Museum Wales, UK)
The term “diagenesis” is used for a broad range of processes in sedimentology, including early, late, chemical, and physical alteration. Many of these processes influence the transformation from soft sediment into solid rock. Thereby, paleoenvironmental information can be lost, or even worse, an artificial signal can be introduced. The identification and evaluation of diagenetic processes is vital to accurately interpret and reconstruct palaeoe-nvironmental conditions. This session invites contributions from the wide field of diagenesis, including e.g. the identification and differentiation of diagenetic processes, case studies from fresh water, restricted marine and full marine environments. We welcome abstracts with suggestions on how to circumvent diagenetic overprints in the fields of palaeontology, palaeoclimatology, paleo- ceanography, cyclostratigraphy and sedimen-tology. But we also encourage abstracts warning for potential biases introduced by diagenesis in these fields of study. In other words, this session aims to revive the discussion within this long-standing debate in sedimentology.