T173 Friend to the Cephalopods: Honoring Neil Landman’s Contributions to Cephalopod Paleobiology (Posters)

Tuesday, 17 October 2023
8:00 AM - 5:30 PM
Hall B

PALEOCLIMATE OF THE CRETACEOUS–PALEOGENE GULF COASTAL PLAIN AND ITS RELATIONSHIP TO EXTINCTION PATTERNS

Paper number: T173-4
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

The Gulf Coastal Plain (GCP) has long been a target for studies of faunal extinction patterns across the Cretaceous–Paleogene (KPg) boundary due to its abundance of well-preserved invertebrate faunas. Previous work has focused on the KPg extinction event itself and environmental change directly caused by the Chicxulub impact. However, marine environments preceding and following the impact need better characterization to interpret taxonomic and ecological changes. With this new information, we can determine which marine environments supported survivorship, extinction, and evolution of species and their communities before, during, and after the impact. Temperature and salinity have been shown to have a first-order control on survivorship and distribution change in modern shallow shelf invertebrate species, thus, here we present clumped isotope data from 6+ KPg boundary sites from four states across the GCP (Arkansas, Alabama, Mississippi, and Georgia) that document Δ47 (a proxy for temperature) and δ18Owater values (a proxy for salinity) over the region before and after the KPg boundary. Seawater temperatures in the region were reconstructed to be 22-27°C and show very little change across the boundary. We show that δ18Owater values across the GCP were similar to the enriched δ18Owater values of the modern Gulf of Mexico, which is much higher than the typically-assumed ice-free end member. This difference between assumed and actual δ18Owater values renders previous δ18Ocarb temperature estimates too high and indicates that the end-Cretaceous GCP may have been environmentally similar to the modern Gulf. We observe a slight increase in δ18Owater into the Paleogene at multiple sites, possibly due to the restriction of the Western Interior Seaway and increase in local salinity. This sizable dataset supports that there was little change in marine environmental conditions on either side of the KPg boundary, suggesting that the short-term change associated with the bolide impact controlled patterns of species and community turnover. The dataset also demonstrates resilience of this shallow shelf environment over time regardless of the existence of short, high-magnitude, perturbation.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-391272

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.