Chemostratigraphy indicates a relatively complete Late Permian to Early Triassic sequence in the western United States

摘要

Although the latest Permian mass extinction and associated δ~(13)C excursion are well documented from the Tethys Ocean, carbonate rocks preserving these events in the eastern Panthalassic Ocean (western Pangea) are unknown. We present δ~(13)C_(carb) from the Gerster and Thaynes (Permian and Triassic) Formations in the western United States and document a negative excursion with no evidence for major breaks in continuity. To further constrain the age of the δ~(13)C_(carb) excursion in the absence of index fossils, we analyzed the same samples for ~(87)Sr/~(86)Sr. When examining our new carbon and Sr data in the context of biostratigraphy and sequence stratigraphy, we conclude that parts of the western United States may preserve carbonate successions that span the latest Permian extinction.