Middle Eocene climate instability in the equatorial oceans

Author(s): Kordesch, W. E.; Paelike, H.; Edgar, K. M.; Bohaty, S. M.; Wilson, P.
Author Affiliation(s): Primary:
National Oceanography Centre, Southampton, United Kingdom
University of Bremen, MARUM Center for Marine Environmental Sciences, Bremen, Germany
Cardiff University, School of Earth and Ocean Sciences, Cardiff, United Kingdom
Volume Title: AGU 2013 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2013; American Geophysical Union 2013 fall meeting, San Francisco, CA, Dec. 9-13, 2013. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Long-term cooling through the middle Eocene (49 to 37 million years ago, Ma) was punctuated by several transient events, notably global warming at the Middle Eocene Climate Optimum (MECO; ≈40 Ma) and a series of inferred cooling episodes associated with Carbonate Accumulation Events (CAE) in the Pacific Ocean. The mechanisms responsible for MECO warming are not well understood, and debate remains regarding the timing and extent of Eocene glaciation. Current knowledge of middle Eocene climate events has been hindered in part by recovery of deep-sea sections that contain discontinuous sediments with poor age control -- particularly in low-latitude regions. This project aims to increase the fidelity and resolution of middle Eocene records and to test the pervasiveness of recently documented transient events at sites around the globe. In this study, we present new mono-specific benthic foraminiferal stable isotope records (δ18O and δ13C) from two equatorial sites: IODP Site U1333 in the Pacific Ocean (10°30.996'N, 138°25.159'W; 4853 mbsl) and from ODP Site 929 in the Atlantic Ocean (5°58.568'N, 43°44.402'). At Site U1333 we have constructed new high-resolution (≈10 kyr) records spanning the interval between ≈43.0 and 38.5 Ma from a stratigraphically continuous section with excellent age control. Site 929 sediments are more condensed across the same interval but uniquely show two or more short-lived dissolution pulses during the MECO event. At Site 929 we generated a medium-resolution stable isotope record (≈50 kyr) between 41.5 and 39.5 Ma. These are the first two low latitude records to span the entirety of the MECO event and the onset of CAE-3. We also present a multi-site stable isotope comparison of records across the middle Eocene to provide new constraints on changes in ocean temperature, continental ice volume, and global carbon cycling.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Ceara Rise; Cenozoic; Climate change; Cores; East Pacific; Eocene; Equatorial Atlantic; Equatorial Pacific; Expedition 320; Expeditions 320/321; IODP Site U1333; Integrated Ocean Drilling Program; Leg 154; Marine sediments; Middle Eocene; North Atlantic; North Pacific; Northeast Pacific; ODP Site 929; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleogene; Sediments; Tertiary
Coordinates: N055834 N055834 W0434423 W0434423
N103100 N103100 W1382510 W1382510
Record ID: 2014051750
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