Geological Society of America

222 D58. Recent Advances in Paleoclimatology and Paleoceanography

Wednesday, 7 November 2018
8:00 AM - 12:00 PM
Room 138-139

EVOLUTION OF LATE CRETACEOUS MERIDIONAL TEMPERATURE GRADIENTS

Paper number: 222-4
Program: Technical Sessions
Time: 8:45 AM – 9:00 AM

Authors

Robin R. Dawson Presenting Author
Yale University, New Haven, CT
Hagit P. Affek
The Hebrew University of Jerusalem, Jerusalem
Pincelli Hull
Yale University, New Haven, CT
Charlotte L. O'Brien
Yale University, New Haven, CT
Mark Pagani
Yale University, New Haven, CT
Bradley Sageman
Northwestern University, Evanston, IL
Daren A. McGregor
Syracuse University, Syracuse, NY
Linda Ivany
Syracuse University, Syracuse, NY
Neil Landman
American Museum of Natural History, New York, NY
James Cochran
Stony Brook UniversityMarine & Atmospheric Scienc, Elko, NV

Abstract

During the Late Cretaceous, Earth’s climate experienced a shift from the warmest conditions of the past ~100 Myr, the Cenomanian-Turonian super-greenhouse (~100-90 Ma), to the relatively cooler greenhouse climate of the Campanian-Maastrichtian (~80-66 Ma). Despite considerable proxy data and climate modeling efforts, Late Cretaceous climate dynamics are still poorly understood. Existing temperature proxy data suggest that latitudinal temperature gradients were much shallower during the super-greenhouse as compared to today, although climate models often have difficulty reproducing these patterns. Here, we present the first carbonate clumped isotope (Δ₄₇)temperature estimates from fossil mollusks within the Western Interior Seaway (WIS) during the warmest, highest CO₂ interval of the Late Cretaceous, the Cenomanian-Turonian, together with new Δ₄₇data from the lower CO₂interval of the Campanian-Maastrichtian. Our Δ₄₇temperatures agree well with previous proxy estimates (TEX₈₆ and δ¹⁸O) and confirm that the mid-latitudes experienced cooling of up to ~10°C during the Late Cretaceous. Combining all proxy data, from this study and previous including Δ_47,TEX₈₆ and δ¹⁸O, the absolute latitudinal gradient steepens significantly from the Cenomanian-Turonian (~0.07 °C/°latitude) into the Campanian-Maastrichtian (~0.4 °C/°latitude). This contrasts with prior model results of temperature gradients across these interval, which suggest very little change, and suggest that meridional climate dynamics representative of extreme greenhouse worlds have yet to be captured by climate models.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-321421

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