Millennial-scale variability to 735 ka: High-resolution climate records from Santa Barbara Basin, CA

Authors

  • Sarah M. White,

    Corresponding author
    1. Geology Department, University of California, Davis, California, USA
    • Corresponding author: S. M. White, Department of Earth and Planetary Sciences, University of California, Santa Cruz 1156 High Street, EMS Bldg, Rm A232 Santa Cruz, CA 95064, USA. (smwhite@ucsc.edu)

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  • Tessa M. Hill,

    1. Geology Department, University of California, Davis, California, USA
    2. Bodega Marine Laboratory, Bodega Bay, California, USA
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  • James P. Kennett,

    1. Department of Earth Science, University of California Santa Barbara, Santa Barbara, California, USA
    2. Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA
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  • Richard J. Behl,

    1. Department of Geological Sciences, California State University, Long Beach, California, USA
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  • Craig Nicholson

    1. Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA
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Abstract

[1] Determining the ultimate cause and effect of millennial-scale climate variability remains an outstanding problem in paleoceanography, partly due to the lack of high-resolution records predating the last glaciation. Recent cores from Santa Barbara Basin provide ~2500–5700 year “windows” of climate with ~10–50 year resolution. Ages for three cores, determined by seismic stratigraphic correlation, oxygen isotope stratigraphy, and biostratigraphy, date to ~293 ka (MIS 8), ~450 ka (MIS 12), and ~735 ka (MIS 18). These records sample the Late Pleistocene, during which the 100 kyr cycle strengthened and the magnitude of glacial-interglacial cyclicity increased. Thus, these records provide a test of the dependence of millennial-scale behavior on variations in glacial-interglacial cyclicity. The stable isotopic (δ18O) composition of planktonic foraminifera shows millennial-scale variability in all three intervals, with similar characteristics (duration, cyclicity) to those previously documented during MIS 3 at this site. Stadial G. bulloides δ18O values are 2.75–1.75‰ (average 2.25‰) and interstadial values are 1.75–0.5‰ (average 1‰), with rapid (decadal-scale) interstadial and stadial initiations of 1-2‰, as in MIS 3. Interstadials lasted ~250–1600 years and occurred every ~650–1900 years. Stadial paleotemperatures were 3.5–9.5°C and interstadial paleotemperatures were 7.5–13°C. Upwelling, evidenced by planktonic foraminiferal assemblages and δ13C, increased during interstadials, similar to MIS 3; high productivity during some stadials was reminiscent of the Last Glacial Maximum. This study builds upon previous records in showing that millennial-scale shifts were an inherent feature of Northern Hemisphere glacial climates since 735 ka, and they remained remarkably constant in the details of their amplitude, cyclicity, and temperature variability.

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