Middle to late Eocene carbonate accumulation events in the Equatorial Pacific; new high resolution geochemical records from IODP Exp 320/321 and ODP Leg 199

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Author(s): Westerhold, T.; Roehl, U.; Lyle, M. W.; Pälike, H.; Wilkens, R. H.
Author Affiliation(s): Primary:
University of Bremen, Department of Geosciences, Bremen, Germany
Texas A&M University, Department of Oceanography, College Station, TX, United States
University of Southampton, School of Ocean & Earth Sciences, Southampton, United Kingdom
University of Hawaii, Institute of Geophysics and Planetology, Honolulu, HI, United States
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Seven Carbonate Accumulation Events (CAEs) were identified in the late Eocene at ODP Site 1218 and 1219 in the equatorial Pacific, each characterized by high-carbonate burial, a relatively deep Carbonate Compensation Depth (CCD), and oxygen isotope values demonstrating relatively cool global conditions. The main driver for the CAEs was interpreted to represent different carbon reservoirs in the carbon cycle interacting with climate (Lyle et al., 2005, Proc. ODP, Sci. Results, 199). However, the data resolution was limited and a precise age model was still lacking both essential to unravel the ultimate causes of the CAEs as well as their potential relation to orbital cycles. Here we present Ca, Si, and Fe intensity data from XRF core scanning of more than 1200 meters of sediment from IODP Exp. 320 (new Sites U1331-U1334) and ODP Leg 199 (Sites 1218-1220) spanning magnetic polarity chrons C13n to C20n (34 to 44 Ma). Ca elemental intensity data have been transferred into carbonate records using CaCO3 values analyzed on discrete samples. This comprehensive dataset proved to be ideal to reconstruct carbonate content at unprecedented resolution. The depth transect including seven sites significantly contributes to an improved spatial view of the CAEs in the equatorial Pacific. The CAEs are expressed as sharp carbonate concentration fluctuations at ≈35, 37.5, 39, 41, 44, 46 Ma across Sites U1331-U1334 and 1218, and reveal a highly dynamic middle to late Eocene environment. The CAEs-bearing interval in the Eocene is followed by a sharp transition into much higher carbonate accumulation rates in the Oligocene. The newly developed cyclostratigraphic age model of our new depth transect indicates that the CAEs are related to fluctuations in the very long eccentricity cycle suggesting a close connection to long-term variations in the carbon cycle.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Chemical composition; East Pacific; Eocene; Equatorial Pacific; Expedition 320; Expedition 321; Expeditions 320/321; Geochemistry; IODP Site U1331; IODP Site U1334; Integrated Ocean Drilling Program; Leg 199; North Pacific; Northeast Pacific; ODP Site 1218; ODP Site 1219; Ocean Drilling Program; Pacific Ocean; Paleoclimatology; Paleogene; Tertiary
Coordinates: N074800 N074800 W1420100 W1420100
N085300 N085300 W1352200 W1352200
Record ID: 2014054456
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