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The Permian witnessed some of the most profound climatic, biotic, and tectonic events in Earth’s history. Global orogeny leading to the assembly of Pangea culminated by middle Permian time, and included multiple orogenic belts in the equatorial Central Pangean Mountains, from the Variscan-Hercynian system in the East to the Ancestral Rocky Mountains in the West. Earth’s penultimate global icehouse peaked in early Permian time, transitioning to full greenhouse conditions by late Permian time, constituting the only example of icehouse collapse on a fully vegetated Earth. The Late Paleozoic Ice Age was the longest and most intense glaciation of the Phanerozoic. Reconstructions of atmospheric composition in the Permian record the lowest CO2 and highest O2 levels of the Phanerozoic, with average CO2 levels comparable to the Quaternary, rapidly warming climate. Fundamental shifts occurred in atmospheric circulation: a global megamonsoon developed, and the tropics became anomalously arid with time. Extreme environments are well documented in the form of voluminous dust deposits, acid-saline lakes and groundwaters, extreme continental temperatures and aridity, and major shifts in biodiversity, ultimately culminating in the largest extinction of Earth history at the Permian-Triassic boundary.The Deep Dust project seeks to elucidate paleoclimatic conditions and forcings through the Permian at temporal scales ranging from millennia to Milankovitch cycles and beyond by acquiring continuous core in continental lowlands known to harbor stratigraphically complete records dominated by loess and lacustrine strata. Our initial site is in the midcontinental U.S.— the Anadarko Basin (Oklahoma), which harbors a complete continental Permian section from western equatorial Pangaea. We will also address the nature and character of the modern and fossil microbial biosphere, the chemistry of saline lake waters and groundwaters, Mars-analog conditions, and exhumation histories of source regions. Importantly, data from Deep Dust will be integrated with Earth-system modelling. This is crucial for putting the (necessarily local) drill core data into the broader global context and for understanding relevant mechanisms and feedbacks of the Permian Earth system.
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Dust and loess as archives and agents of climate and climate change in the late Paleozoic Earth system
Abstract Palaeo-loess and silty aeolian-marine strata are well recognized across the Carboniferous–Permian of equatorial Pangaea. Aeolian-transported dust and loess appear in the Late Devonian in the west, are common by the Late Carboniferous, and predominate across equatorial Pangaea by the Permian. The thickest loess deposits in Earth history – in excess of 1000 m – date from this time, and archive unusually dusty equatorial conditions, especially compared to the dearth of equatorial dust in the Cenozoic. Loess archives a confluence of silt generation, aeolian emission and transport, and ultimate accumulation in dust traps that included ephemerally wet surfaces and epeiric seas. Orogenic belts sourced the silt, and mountain glaciation may have exacerbated voluminous silt production, but remains controversial. In western Pangaea, large rivers transported silt westward, and floodplain deflation supplied silt for loess and dust. Expansion of dust deposition in Late Pennsylvanian time records aridification that progressed across Pangaea, from west to east. Contemporaneous volcanism may have created acidic atmospheric conditions to enhance nutrient reactivity of dusts, affecting Earth's carbon cycle. The late Paleozoic was Earth's largest and most long-lived dust bowl, and this dust represents both an archive and agent of climate and climate change.
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- Award ID(s):
- 1849754
- PAR ID:
- 10555835
- Publisher / Repository:
- DOI PREFIX: 10.1144
- Date Published:
- Journal Name:
- Geological Society, London, Special Publications
- Volume:
- 535
- Issue:
- 1
- ISSN:
- 0305-8719
- Format(s):
- Medium: X Size: p. 195-223
- Size(s):
- p. 195-223
- Sponsoring Org:
- National Science Foundation
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