30 D20. Recent Advances in Stratigraphy (Posters)

Sunday, 22 September 2024
8:00 AM - 5:30 PM
Hall D

PRELIMINARY EARLY EOCENE TERRESTRIAL RECORD FROM THE WIND RIVER BASIN, WYOMING, USA

Paper number: 30-10
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

During the early Eocene, the Wind River Basin in central Wyoming was a dynamic fluvial landscape that was responding to both contemporaneous uplift during the Laramide Orogeny and fluctuating early Eocene climate patterns. The early Eocene was marked by a series of rapid injections of CO2 into the atmosphere causing periods of rapid warming and increasingly variable climatic patterns, providing a useful deep-time analog for anthropogenically induced climate change. Previous work from the Bighorn Basin of northern Wyoming identifies multiple negative carbon isotope excursions during the Paleogene tied to atmospheric CO2 changes. This injection of CO2 into the atmosphere is linked to a global increase in temperature, but other coeval records are needed to understand the overall impact on the landscape. The Wind River Basin preserves an understudied early Eocene fluvial record which provides a unique opportunity to compare hyperthermal induced terrestrial environmental change in western North America.

A high resolution stratigraphic analysis of multiple localities in the basin is needed to set the framework for future paleoclimate reconstructions. This project focuses on two sites in the Wind River Basin: (1) Hell’s Half Acre near the town of Casper in the east and (2) Painted Hills near the town of Dubois in the west. The Indian Meadows and Wind River Formations have previously been interpreted to represent braided fluvial systems, but age control in the early Eocene is limited to biostratigraphy from mammals and maximum depositional ages from detrital zircons. Ongoing work to develop an early Eocene magnetostratigraphic age model for the Wind River Basin will aid in correlation to basinal, regional, and global records. Our preliminary stratigraphic work indicates that the depositional environments for the sites consist of braided channel systems and their associated floodplains with moderate- to well-developed paleosols appropriate for paleoclimate proxies. The majority of the paleosols are identified as paleo-Vertisols with abundant carbonate nodules. Future work will focus on traditional stable isotopes (δ18O and δ13C) to identify carbon isotope excursions and clumped isotopes (Δ47) to quantify temperature changes in these hyperthermal events.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404922

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