T183 Soils and Paleosols across Space and Time II: A Celebration of Steven G. Driese

Tuesday, 11 October 2022
1:30 PM - 5:30 PM
207

HOT ENOUGH FOR YA? DETERMINING THE MAGNITUDE OF SOIL TEMPERATURE CHANGE IN THE BIGHORN BASIN, WY AT THE PALEOCENE-EOCENE THERMAL MAXIMUM

Paper number: T183-5
Program: Technical Sessions
Time: 2:20 PM – 2:35 PM

Authors

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) is a well-studied hyperthermal event, and it is often invoked as an analogue for modern rapid warming of the climate. Terrestrial records of the PETM are particularly useful for understanding how the hydrosphere and biosphere respond to rapid global warming, which may help the scientific community make better policy recommendations for the future. The Bighorn Basin, Wyoming USA, preserves a sequence of paleosols with abundant carbonate nodules that provide a unique opportunity to investigate terrestrial temperature change through the PETM at relatively high temporal resolution. These nodules have already yielded a carbon isotope records that confirms the preservation of the PETM in the basin, as well as unique features like the presence of a smaller carbon isotope excursion (CIE) that immediately precedes the major CIE of the PETM, as well as the recovery period following the peak excursion. In addition, quantifying the temperature change through the PETM provides critical context for floral and faunal turnovers that have been observed during the body of the PETM in the Bighorn Basin.

Here, we present a record of temperature change from clumped isotope thermometry (T(Δ47)) of Bighorn Basin paleosol carbonate nodules through the PETM. Our preliminary record shows 12°C of warming in paleosols from pre-PETM conditions to the body of the PETM, with T(Δ47) values up to 41°C during the body of the PETM. Prior T(Δ47) studies for these nodules suggest that the temperatures reflect carbonate formation during the warm season. Here, we will add to this interpretation based on the comparison to photomicrographs and isotope datasets of modern fine-grained, clay rich soils; these modern sites may be better analogs for the Bighorn Basin paleosols than sites used in previous studies of T(Δ47) in modern soils. We will compare our inferred summertime temperatures with mean annual air temperatures inferred from the floral record, and observations of community change observed in the palynological and paleontological record.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383086

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