T128 Cenozoic Paleoclimates and Ecosystems II

Monday, 23 October 2017
1:30 PM - 5:30 PM
Room 609

MARINE BIOTIC RESPONSE OF THE NORTHERN ATLANTIC OCEAN DURING GRADUAL AND ABRUPT WARMING EVENTS FROM THE LATE PALEOCENE TO THE EARLY-MIDDLE EOCENE

Paper number: T128-9
Program: Technical Sessions
Time: 3:30 PM – 3:45 PM

Authors

Abstract

The latest Paleocene to the early-middle Eocene (~58 to 48 Ma) was climatically dynamic, experiencing elevated global temperatures and atmospheric carbon dioxide (CO2) levels across both gradual and geologically brief episodes. Transient warming events known as ‘hyperthermals’ punctuated the long-term warming trend, typically lasting <200 kyr in duration. These are characteristically associated with negative carbon isotope excursions and dissolution of deep-sea carbonates, suggesting an association with massive changes to the exogenic carbon reservoir. Hyperthermals thus likely indicate the release and/or redistribution of large quantities of isotopically light (13C-depleted) carbon to the atmosphere and oceans. Throughout this time, hyperthermals vary in magnitude, making them effective case studies for future climate change driven by anthropogenic CO2 emissions.

The marine biological pump describes the fixation of carbon in surface waters through primary production and its transport to the deep-sea. Biogenic barium (Babio) has been widely applied as a proxy for the strength of the biological pump, since barite is formed during the degradation of sinking organic matter. Understanding connections between the marine biological pump and climatic perturbations of varying magnitude and duration will provide context for predicting the behavior of the biological pump in the future.

Here we present new bulk and benthic stable isotopic carbon (δ13C) and oxygen (δ18O) records from the Integrated Ocean Drilling Program (IODP) Site U1409, recovered offshore Newfoundland. We compare these records with Ocean Drilling Program (ODP) Site 1258 (Demerara Rise, Equatorial Atlantic) and ODP Site 1262 (Walvis Ridge, South Atlantic) to discriminate probable global climatic events. Additionally, we present an X-Ray Florescence (XRF) derived barium/iron (Ba/Fe) record and select, preliminary barite measurements from Site U1409 to evaluate trends in export production coincident with hyperthermals and long-term trends in climate. Our new records suggest that the Early Eocene was a time of high export production in this region and that transient increases in export coincided with short-lived warming events.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-298467

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