Export productivity and carbonate accumulation in the Pacific Basin at the transition from a greenhouse to icehouse climate (late Eocene to early Oligocene)

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doi: 10.1029/2010PA001932
Author(s): Griffith, Elizabeth; Calhoun, Michael; Thomas, Ellen; Averyt, Kristen; Erhardt, Andrea; Bralower, Timothy; Lyle, Mitchell W.; Olivarez-Lyle, Annette; Paytan, Adina
Author Affiliation(s): Primary:
University of California at Santa Cruz, Institute of Marine Sciences, Santa Cruz, CA, United States
Other:
Wesleyan University, United States
Pennsylvania State University, United States
Texas A&M University, United States
Volume Title: Paleoceanography
Source: Paleoceanography, 25(3). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 101 refs.; illus., incl. 2 tables, sketch map
Summary: The late Eocene through earliest Oligocene (40-32 Ma) spans a major transition from greenhouse to icehouse climate, with net cooling and expansion of Antarctic glaciation shortly after the Eocene/Oligocene (E/O) boundary. We investigated the response of the oceanic biosphere to these changes by reconstructing barite and CaCO3 accumulation rates in sediments from the equatorial and North Pacific Ocean. These data allow us to evaluate temporal and geographical variability in export production and CaCO3 preservation. Barite accumulation rates were on average higher in the warmer late Eocene than in the colder early Oligocene, but cool periods within the Eocene were characterized by peaks in both barite and CaCO3 accumulation in the equatorial region. We infer that climatic changes not only affected deep ocean ventilation and chemistry, but also had profound effects on surface water characteristics influencing export productivity. The ratio of CaCO3 to barite accumulation rates, representing the ratio of particulate inorganic C accumulation to Corg export, increased dramatically at the E/O boundary. This suggests that long-term drawdown of atmospheric CO2 due to organic carbon deposition to the seafloor decreased, potentially offsetting decreasing pCO2 levels and associated cooling. The relatively larger increase in CaCO3 accumulation compared to export production at the E/O suggests that the permanent deepening of the calcite compensation depth (CCD) at that time stems primarily from changes in deep water chemistry and not from increased carbonate production.
Year of Publication: 2010
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Barite; Calcium carbonate; Cenozoic; Chemostratigraphy; Chronostratigraphy; Clastic sediments; Cores; DSDP Site 574; Deep Sea Drilling Project; East Pacific; Eocene; Equatorial Pacific; IPOD; Leg 198; Leg 199; Leg 85; Lithostratigraphy; Lower Oligocene; Marine sediments; North Pacific; Northeast Pacific; Northwest Pacific; ODP Site 1209; ODP Site 1210; ODP Site 1211; ODP Site 1218; Ocean Drilling Program; Oligocene; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleogene; Sand; Sediments; Shatsky Rise; Sulfates; Tertiary; Upper Eocene; West Pacific
Coordinates: N323900 N324000 E1583100 E1583000
N321300 N321300 E1581600 E1581600
N320000 N320000 E1575100 E1575100
N085300 N085300 W1352200 W1352200
N041231 N041232 W1331948 W1331949
Record ID: 2013034370
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