Report on ICDP Deep Dust workshops: probing continental climate of the late Paleozoic icehouse–greenhouse transition and beyond

Abstract

Abstract. Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian – the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies – boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed “Deep Dust,” held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on clarifying the scientific drivers and key sites for coring continuous sections of Permian continental (loess, lacustrine, and associated) strata that preserve high-resolution records. Combined, the two workshops hosted a total of 91 participants representing 14 countries, with broad expertise. Discussions at Deep Dust 1.0 (USA) focused on the primary research questions of paleoclimate, paleoenvironments, and paleoecology of icehouse collapse and the run-up to the Great Dying and both the modern and Permian deep microbial biosphere. Auxiliary science topics included tectonics, induced seismicity, geothermal energy, and planetary science. Deep Dust 1.0 also addressed site selection as well as scientific approaches, logistical challenges, and broader impacts and included a mid-workshop field trip to view the Permian of Oklahoma. Deep Dust 2.0 focused specifically on honing the European target. The Anadarko Basin (Oklahoma) and Paris Basin (France) represent the most promising initial targets to capture complete or near-complete stratigraphic coverage through continental successions that serve as reference points for western and eastern equatorial Pangaea.

Reconsidering Carboniferous–Permian continental paleoenvironments in eastern equatorial Pangea: facies and sequence stratigraphy investigations in the Autun Basin (France)

“…As these areas likely constituted a considerable atmospheric CO2 sink through the storage of organic carbon in sediments, they would have constituted a major driving factor on the climate, especially at that time (e.g., Montañez et al 2016;Richey et al 2020). Given the sensitivity of the equatorial continental areas to climate forcing (e.g., Soreghan et al 2020) Fig. 3 Illustration of the facies associations corresponding to the littoral lake environments (L1 and L2 facies associations; see Table 1 for the facies codes).…”

“…Given the presence of large tropical rainforests (Cleal and Thomas 2005) and the tremendous rates of organic carbon burial in sediments at that time (i.e., coal and black shale deposits), intertropical areas constituted a major atmospheric CO2 sink. It is therefore of utmost importance to explore paleointertropical basins because their sensitivity to climate forcings has been underestimated in paleoclimate scenarios (e.g., Soreghan et al 2020). At that time, intertropical latitudes are mainly considered as a mountainous region submitted to tropical weathering (e.g., Goddéris et al 2017), and therefore mainly in erosion;active sedimentation areas are not fully considered in either the terrestrial paleogeography reconstructions or in the climate modelling.…”

The Brécy depocenter as part of a new northern Massif Central Carboniferous–Permian Basin (France)

“…They were filled with siliciclastic volcanoclastic continental material-from alluvial to lacustrine through fluvial environments-at intertropical latitudes [Donsimoni, 1990, Gand, 2003, Mercuzot et al, 2021, Schäfer, 2011, Schneider and Romer, 2010, Soreghan et al, 2020. LOCPB were also accompanied by widespread intrusive and extrusive magmatic activity with a crustal or mantle origin with mostly felsic and rare mafic signatures [Neumann et al, 2004, Timmerman, 2004, McCann et al, 2006.…”

“…One good way to discuss the tectono-sedimentary history of hidden subsurface LOCBP is to use seismic data to look for them under their Meso-Cenozoic sedimentary cover given that they may be considered as fossil basins with preserved pre-Triassic depositional and structural patterns. We present new results from the interpretation of industrial seismic lines spanning 115 kilometers, while targeting the Brécy depocenter in the southwest Paris Basin, which has recently been reprocessed within the framework of an International Continental Scientific Drilling Program proposal [ICDP Deepdust project; Soreghan et al, 2020]. First, we aim to discuss the structural features, thickness and tectonic evolution of the Brécy depocenter and the related sedimentary filling using seismic and well data.…”

The Late Paleozoic Ice Age in western equatorial Pangea: Context for complex interactions among aeolian, alluvial, and shoreface sedimentary environments during the Late Pennsylvanian – early Permian

“…Steele, 1987;Chan, 1989). This Late Pennsylvanian -Permian succession was deposited during the Late Paleozoic Ice Age (LPIA; Fielding et al, 2008;Montañez et al, 2016;Griffis et al, 2022) and is located in the central Pangean equatorial region (Soreghan et al, 2020). In consequence, these early Permian series provide an opportunity to study the variation of depositional environments, vegetation preservation and stratigraphic cycles considering sea-level, tectonics and sediment supply variations within glacial-interglacial phases in the equatorial Pangea.…”