221-3 Correlating paleoenvironment with biotic recovery within the Virgin Limestone at Lost Cabin Spring, NV

Session: Phanerozoic Earth System Shifts in the Marine Sedimentary Record (Posters)

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Abstract:

The End-Permian mass extinction, brought on by the eruption of the Siberian Traps large igneous province, resulted in high sea surface temperatures and stratified, anoxic ocean waters, leading to the extinction of at least 76% of marine species. Biotic recovery following the End-Permian mass extinction was complex, with recovery rates that varied greatly across different environmental settings, with some studies showing rapid recovery, while others show slow and/or inconsistent recovery throughout the entire Early Triassic. Previous studies have shown that the recovery of marine ecosystems within the paleotropical waters along the western margin of Pangaea was slow, taking place from the Permian-Triassic boundary through at least the early Middle Triassic. Analysis of deeper water facies documented incursions of anoxic bottom waters onto the continental shelf, while surface waters in the region were subject to increased sea-surface temperatures, likely contributing to a sluggish biotic recovery (Woods et al., 2019). The Lower Triassic (Spathian) Virgin Limestone is predominantly comprised of interbedded limestone and shale deposited on the margin of equatorial Pangaea in an intertidal to middle ramp setting, and was concurrent with the biotic recovery following the End-Permian extinction event. The interbedded nature of the Virgin Limestone provides a means to examine interactions between oxygenation levels and biotic recovery following the End-Permian extinction and to test the hypothesis of Woods et al. (2019) that harsh environmental conditions were responsible for determining the timing and strength of biotic recovery following the End-Permian mass extinction. This study focuses on the Virgin Limestone at Lost Cabin Spring, in southwestern Nevada. Biotic recovery is being assessed through outcrop observations of body fossil content, ichnofabric, and trace fossil type and abundance within limestone beds. Paleoxygenation and paleoproductivity are being reconstructed via geochemical data derived from interbedded shale units. The combination of paleoenvironmental data from the shales and recovery data from the limestone beds will allow for the relationship between recovery and environmental stress to be ascertained. Results will yield insights into the effect of paleoenvironmental stresses on recovery rates following major mass extinction events, including the current modern mass extinction.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9693

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