Determining the ultimate cause and effect of millennial-scale climate variability remains an outstanding problem in paleoclimatology, partly due to the lack of high- resolution records extending beyond the last glacial period. New cores from Santa Barbara Basin provide ∼5000 year "windows" of climate with ∼50-year resolution dating to ∼293 ka (the MIS 8.6-8.5 transition), ∼460 ka (MIS 12), and ∼735 ka (MIS 18). These records span the Late Pleistocene, during which the 100-kyr cycle gained power in global climate records 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. Planktonic foraminiferal δ 18O indicates that millennial-scale variability is present in all three intervals, and is similar to that during MIS 3. Stadial G. bulloides δ18O values were 2.75-1.75 ‰ (mean 2.25 ‰) and interstadial values were 1.75-0.5 ‰ (mean 1 ‰), with rapid interstadial initiations of 1-2 ‰, as in MIS 3. Interstadials were ∼300-1300 years long and spaced ∼750-1500 years apart, consistent with MIS 3 interstadial durations. Upwelling increased during interstadials, but did not vary synchronously with surface water temperatures, again similar to MIS 3. These high-resolution records provide evidence that millennial-scale variability was an inherent feature of glacial climates in the Northern Hemisphere throughout the past 735 ka.
|Advisor:||Hill, Tessa M.|
|Commitee:||Montanez, Isabel P., Spero, Howard J.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||MAI 51/03M(E), Masters Abstracts International|
|Subjects:||Paleoclimate Science, Geochemistry|
|Keywords:||Abrupt, Carbon, Isotope, Micropaleontology, Oxygen, Paleoceanography|
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