Peak intervals of Equatorial Pacific export production during the middle Miocene climate transition

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doi: 10.1130/G38290.1
Author(s): Carter, Samantha C.; Griffith, Elizabeth M.; Penman, Donald E.
Author Affiliation(s): Primary:
University of Texas at Arlington, Department of Earth and Environmental Sciences, Arlington, TX, United States
Yale University, United States
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 44(11), p.923-926. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. GSA Data Repository item 2016310. 36 refs.; illus., incl. sketch map
Summary: The middle Miocene climate transition (MMCT) is characterized by an abrupt 1 ppm increase in benthic foraminiferal oxygen isotopes at ca. 13.8 Ma, marking expansion of the Antarctic Ice Sheet and transition of Earth's climate to a cooler, relatively stable glacial state. Also occurring during this period is a globally recognized positive carbon isotope excursion (16.9-13.5 Ma) in benthic and planktonic foraminifera with shorter carbon isotope maxima (CM) events, linking hypotheses for climate change at the time with the carbon cycle. In order to test whether export production in the eastern equatorial Pacific is related to the largest such event (CM6), coincident with Antarctic Ice Sheet expansion, a high-resolution (<5 k.y.) record of export production at Integrated Ocean Drilling Program Site U1337 spanning the MMCT (14.02-13.43 Ma) was produced using marine pelagic barite mass accumulation rates. Export production is elevated with an extended period of more than double present-day values. These variations are not orbitally paced and provide evidence for a reorganization of nutrients supplied to the eastern equatorial Pacific in the Miocene and intensification of upwelling. If such changes are representative of the entire region, then this mechanism could sequester enough carbon to have a significant effect on atmospheric pCO2 However, continual delivery of nutrients to the surface waters of the eastern equatorial Pacific is required in order to sustain export production without depleting the surface ocean of limiting nutrients. This might be accomplished by a change in ocean circulation or a combination of other processes requiring further study.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; C-13/C-12; Carbon; Carbon dioxide; Cenozoic; Chemostratigraphy; Climate change; Climate forcing; Cores; East Pacific; Equatorial Pacific; Expedition 321; Expeditions 320/321; Foraminifera; IODP Site U1337; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Marine sediments; Microfossils; Middle Miocene; Miocene; Models; Neogene; North Pacific; Northeast Pacific; O-18/O-16; Orbital forcing; Oxygen; Pacific Ocean; Paleoclimatology; Paleoecology; Paleoenvironment; Productivity; Protista; Reconstruction; Sediments; Stable isotopes; Tertiary
Coordinates: N035000 N035000 W1231222 W1231222
Record ID: 2016094415
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data supplied by the Geological Society of America