Geological Society of America

T36 Oceans and Climates throughout Earth’s History: From Proxy Reconstructions to Model Assessments (Posters)

Sunday, 22 September 2019
9:00 AM - 5:30 PM
Hall AB, North Building

LARGE VOLUME TURBIDITE DEPOSITION ON CONTINENTAL MARGINS IN A GREENHOUSE WORLD: THE EARLY EOCENE CLIMATIC OPTIMUM (EECO)

Paper number: T36-21
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Tim McHargue Presenting Author
Stanford University, Stanford, CA
Zack Florentino Murguia Burton
Stanford University, Stanford, CA
Tyler Kukla
Stanford UniversityGeological Sciences, Palo Alto, CA
Roger Bloch
San Carlos, CA
Jared T. Gooley
Stanford University, Stanford, CA
Stephan A. Graham
Stanford University, Stanford, CA
Jake Harrington
Stanford University, Stanford, CA
Chayawan Jaikla
Stanford University, Stanford, CA
Christopher Henry Kremer
Brown University, Providence, RI

Abstract

We evaluate the hypothesis that during a prolonged eustatic highstand, deep ocean passive margin basins can accumulate substantial volumes of turbidity current deposits. To test this hypothesis we compiled an inventory (97 locations) of the global distribution of deep ocean siliciclastic turbidites that accumulated during the Early Eocene Climatic Optimum (EECO) or bounding time intervals. The EECO is a prolonged interval characterized by minimal glaciation and exceptionally high atmospheric and ocean temperatures. Eustatic sea level was abnormally high and, apart from possible Milankovich effects, relatively stable for approximately 6 Ma. Consequently, the EECO would have been a particularly unfavorable time for continental margin turbidite deposition if falling sea level is a prerequisite for transporting substantial volumes of terrestrial sediment into the deep ocean.

We find that turbidites are common and abundant along tectonically active margins during the EECO and also present on the passive margins of multiple continents. The presence of significant volumes of turbidites in passive continental margin deep ocean basins during the EECO argues in favor of the importance of mechanisms other than falling relative sea level to supply abundant siliciclastic sediments beyond the shelf edge. Most likely, abundant turbidites on passive margins resulted from voluminous sediment supplied by large integrated fluvial drainage systems.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-339587

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