Holocene foraminiferal radiocarbon record of paleocirculation in the Santa Barbara Basin
- 1Department of Geography, University of California, Berkeley, California 94720, USA
- 2Department of Geography and Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA
- 3Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
- 4Department of Geological Sciences, University of California, Santa Barbara, California 93106, USA
Abstract
Differences in radiocarbon apparent ages between coexisting planktonic and benthic (B-P) foraminifers in the Santa Barbara Basin contain information about changes in the age (and thus the source) of water entering the basin. The Holocene sequence indicates a greater variability in circulation than previously detected. During the early Holocene, ca. 9 ka, B-P 14C apparent age differences fluctuated between 220 and 560 14C yr, similar to rapid variations seen during the Younger Dryas and the last glacial episode. During the relatively stable middle Holocene (8.5–2 ka), B-P 14C apparent age differences averaged 440 14C yr. After 2 ka, the average B-P 14C apparent age difference increased to 620 14C yr, which has persisted until the present. The shift in B-P 14C apparent age differences likely represents a change in the strength or source of North Pacific Intermediate Water production and is concurrent with changes in regional climate patterns as well as with changes in temperature and accumulation rates measured in the Greenland Ice Sheet Project 2 ice core, suggesting large-scale changes in atmospheric circulation patterns.
Footnotes
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↵*Present address: Department of Earth System Science, University of California, Irvine, California 92697, USA
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↵GSA Data Repository item 2003046, planktonic and benthic foraminiferal radiocarbon ages, is available on request from Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301-9140, USA,editinggeosociety.org or at www.geosociety.org/pubs/ft2003.htm.
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- Accepted January 9, 2003.
- Received August 6, 2002.
- Revision received January 7, 2003.
- Geological Society of America
