Palaeohydrological Change in a Rapidly Warming World: Clues to Continental Interior Dynamics from the Early Eocene Lake Uinta, Green River Formation, Utah
Abstract
Understanding past climatic states, especially during times of extreme warmth, is crucial for future predictions of hydrologic change during the new warm mode humans have created. The Early Eocene Climatic Optimum (EECO, 53-50 Ma) provides a natural experiment of the impacts of rapid global warming on the Earth system, including hydrological and associated biogeochemical feedbacks.
Here we present compound-specific hydrogen isotopic analyses of n-alkanes, isoprenoids, and hopanes extracted from a 120-m-thick thermally immature sequence preserved in cores that sample a transect from basin margin to centre of the lacustrine Parachute Creek Member of the Green River Formation in the Uinta Basin, Utah, USA. The study interval includes the Mahogany Oil Shale, a deposit unusually rich in TOC (up to 40%). Quantitative δ13Corg data from this non-marine succession can be correlated to marine sections through astrochronology and radioisotopic age constraints from 21 tuff deposits. Comparison of this novel record with additional biomarker profiles and organic petrographic data generated, set within a key stratigraphic context, allows the differentiation of hydrological change from broader ecosystem change during the EECO. We conclude that lake and wetland hydrological change during the early Eocene likely had an under-appreciated role in early Cenozoic greenhouse conditions and affected re-equilibration of the hydrologic cycle in the North American continental interior.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP51F1442E
- Keywords:
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- 1009 Geochemical modeling;
- GEOCHEMISTRY;
- 4914 Continental climate records;
- PALEOCEANOGRAPHY;
- 4924 Geochemical tracers;
- PALEOCEANOGRAPHY;
- 4994 Instruments and techniques;
- PALEOCEANOGRAPHY