13 Time of Transition: Cretaceous Climate, Tectonics, and Evolutionary History II

Monday, 19 May 2025
1:30 PM - 3:15 PM
Cascade E

MOLECULAR PROXIES RECORD TRENDS IN SOUTHERN OCEAN PALEOTEMPERATURES FOR THE CAMPANIAN THROUGH PALEOCENE

Paper number: 13-6
Program: Theme Sessions
Time: 2:45 PM – 3:00 PM

Authors

Abstract

Gradual cooling characterizes the trend in Late Cretaceous climate for southern high latitudes, likely associated with the progressive breakup of Gondwana and widening of the Southern Ocean basin. However, a lack of high-resolution paleotemperature records has constrained assessment of factors controlling this cooling trend. Recovery of Campanian through Paleocene organic-rich sediments (~78 – 60 Ma) from the Transkei Basin (Hole U1581B), offshore South Africa, during IODP Expedition 392 now enables reconstruction of ocean paleotemperatures recording climatic evolution of the late Cretaceous Southern Ocean. Analysis of GDGTs originating from Nitrososphaerota and alkenones derived from haptophyte algae afforded temporal records for sea surface temperatures (SST) based on TEX86 and UK'40 molecular proxies. UK'40 represents an analog of the UK'37 proxy based on the ratio of C40 rather than C37 di- and triunsaturated alken-2-ones. The coherence between TEX86 and UK'40 supports the efficacy of the UK'40 as a Cretaceous temperature proxy and the high sedimentation rate of the sequence captures trends in SSTs. evidence for progressive cooling in the TEX86 record is consistent with other temperature reconstructions for the late Cretaceous. In addition, SSTs stratigraphic profiles for the Transkei Basin reveals several discrete cooling steps during the late Campanian and at the Campanian-Maastrichtian boundary not previously observed for this time interval. Moreover, the location of Hole U1581B suggest that these data may help define the development of the Southern Ocean gyre, which likely influenced the gradual decrease in southern mid-to-high-latitude temperatures.

Geological Society of America Abstracts with Programs. Vol. 57, No. 5

doi: 10.1130/abs/2025RM-409631

© Copyright 2025 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.