Deepdust - A proposed ICDP project to probe continental climate of the Late Paleozoic icehouse-greenhouse transition - focus on the Paris Basin target
Résumé
The tectonic, climatic, and biotic events of the Permian are amongst the most profound in Earth history. Global orogeny leading to Pangaean assembly culminated by early-middle Permian time, and included multiple orogenic belts in the equatorial Central Pangaean Mountains, from the Variscan-Hercynian system (east) to the Ancestral Rocky Mountains (west). Earth’s penultimate global icehouse peaked in early Permian time, transitioning to full greenhouse conditions by late Permian time. The Late Paleozoic Icehouse was the longest and most intense glaciation of the Phanerozoic. The atmosphere during this icehouse experienced the lowest CO2 and highest O2 levels of the Phanerozoic. Fundamental shifts occurred in atmospheric circulation: a global megamonsoon developed and the tropics became anomalously arid with time. We will seek to elucidate paleoclimatic conditions and forcings through the Permian at temporal scales ranging from the sub-millennial to the Milankovitch and beyond by acquiring continuous core in continental lowlands known to harbor stratigraphically complete records dominated by loess and lacustrine strata.We have identified locales in the western U.S. and France as the 2 key coring sites globally to achieve our objectives, as these represent the western and eastern limits, respectively of the Pangaean tropics. Additionally, the Anadarko Basin (Oklahoma) and Paris Basin (France) archive arguably the most complete continental Permian sections at the paleoequator, and their adjacent paleo-uplands are the only sites globally for which Permian low-latitude glaciation has been hypothesized.In the Paris Basin, The Permian section has been investigated using reprocessed seismic data and reassessment of well data; it comprises fine-grained red beds, and extends over an area of several thousand km2, with thicknesses reaching 3500 m.(The Deepdust project, led by G. Soreghan, remains under development and follows the ICDP proposal submission process).