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The California current of the last glacial maximum: Reconstruction at 42?? N based on multiple proxies

Paleoceanography

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Abstract

Multiple paleoceanographic proxies in a zonal transect across the California Current near 42?? N record modem and last glacial maximum (LGM) thermal and nutrient gradients. The offshore thermal gradient, derived from foraminiferal species assemblages and oxygen isotope data, was similar at the LGM to that at present (warmer offshore), but average temperatures were 3.3?? ??1.5?? C colder. Observed gradients require that the sites remained under the southward flow of the California Current, and thus that the polar front remained north of 42?? N during the LGM. Carbon isotopic and foraminiferal flux data suggests enhanced nutrients and productivity of foraminfera in the northern California Current up to 650 km offshore. In contrast, marine organic carbon and coastal diatom burial rates decreased during the LGM. These seemingly contradictory results are reconciled by model simulations of the LGM wind- field, which suggest that wind stress curl at 42?? N (and thus open-ocean upwelling) increased, while offshore Ekman transport (and thus coastal upwelling) decreased during the last ice age. The ecosystem of the northern California Current during the LGM approximated that of the modern Gulf of Alaska. Cooling and production in this region was thus driven by stronger open-ocean upwelling and/or southward flow of high-latitude water masses, rather than by coastal upwelling.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The California current of the last glacial maximum: Reconstruction at 42?? N based on multiple proxies
Series title:
Paleoceanography
Volume
12
Issue:
2
Year Published:
1997
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
191
Last page:
205
Number of Pages:
15