Ocean circulation in the northwestern Pacific (ODP Site 884) from the middle Eocene to the early Oligocene (45-33 Ma)

Author(s): Borrelli, Chiara; Cramer, Benjamin S.; Katz, Miriam E.
Author Affiliation(s): Primary:
Rensselaer Polytechnic Institute, Earth and Environmental Sciences, Troy, NY, United States
Volume Title: Geological Society of America, 2012 annual meeting
Source: Abstracts with Programs - Geological Society of America, 44(7), p.122-123; Geological Society of America, 2012 annual meeting, Charlotte, NC, Nov. 4-7, 2012. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: New high-resolution benthic foraminiferal δ18O and δ13C data from ODP Site 884 (northwestern Pacific) adds significant structure to a low-resolution record (Pak and Miller 1995), providing new insights into paleoceanographic changes from the middle to the late Eocene in the Pacific. Site 884 δ18O data, compared with published ODP records from the Atlantic (Sites 1260 and 1053) and Southern (Site 689) Oceans, indicate that the northwestern Pacific was one of the warmest deepwater locations from the middle middle to the late Eocene (∼46-34 Ma). A comparison among Site 884 and other published ODP Pacific δ13C records (Sites 883, 865, and 1218) suggests that the water mass bathing the northwest Pacific (Site 883 and 884) during the middle middle Eocene was not the same water mass flowing in the western and eastern equatorial Pacific (Sites 865 and 1218). Together, we interpret the δ18O and δ13C comparisons as indicative of a localized deepwater influence in the northwestern Pacific. The relatively low δ13C values recorded at the northwestern Pacific sites in the middle middle Eocene, together with the published neodymium isotopic results and tectonic reconstructions for this region, do not support a deepwater source in the higher latitudes of the North Pacific. However, in the late Eocene, the Site 884 record shifts towards higher δ13C values, implying a change in deepwater circulation. This late Eocene change recorded in the northwestern Pacific may have been related to tectonic movements that opened key Southern Ocean gateways; the formation of a proto- Antarctic Circumpolar Current as a consequence of opening of the Drake Passage and the Tasman Rise has been shown to affect deepwater circulation in the Northern Hemisphere.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctic Circumpolar Current; Atlantic Ocean; C-13/C-12; Carbon; Cenozoic; Demerara Rise; Detroit Seamount; Emperor Seamounts; Eocene; Equatorial Atlantic; IODP Site; Isotope ratios; Isotopes; Leg 113; Leg 145; Leg 207; Lower Oligocene; Maud Rise; Middle Eocene; North Atlantic; North Pacific; Northwest Atlantic; Northwest Pacific; ODP Site 1260; ODP Site 689; ODP Site 884; Ocean Drilling Program; Oligocene; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleoenvironment; Paleogene; Southern Ocean; Stable isotopes; Tertiary; Weddell Sea; West Atlantic; West Pacific
Coordinates: N091600 N091600 W0543300 W0543300
N512702 N512702 E1682013 E1682013
Record ID: 2013047184
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