Climatically related millennial-scale fluctuations in strength of California margin oxygen-minimum zone during the past 60 k.y.

Journal Article · Mon Nov 01 04:00:00 EST 1999 · Geology

DOI:https://doi.org/10.1130/0091-7613(1999)027<0975:CRMSFI>2.3.CO;2· OSTI ID:20003864

Cannariato, K G; Kennett, J P

A strong oxygen-minimum zone (OMZ) currently exists along the California margin because of a combination of high surface-water productivity and poor intermediate-water ventilation. However, the strength of this OMZ may have been sensitive to late Quaternary ocean-circulation and productivity changes along the margin. Although sediment-lamination strength has been used to trace ocean-oxygenation changes in the past, oxygen levels on the open margin are not sufficiently low for laminations to form. In these regions, benthic foraminifera are highly sensitive monitors of OMZ strength, and their fossil assemblages can be used to reconstruct past fluctuations. Benthic foraminiferal assemblages from Ocean Drilling Program Site 1017, off Point Conception, exhibit major and rapid faunal oscillations in response to late Quaternary millennial-scale climate change (Dansgaard-Oeschger cycles) on the open central California margin. These faunal oscillations can be correlated to and are apparently synchronous with those reported from Santa Barbara Basin. Together they represent major fluctuations in the strength of the OMZ which were intimately associated with global climate change--weakening, perhaps disappearing, during cool periods and strengthening during warm periods. These rapid, major OMZ strength fluctuations were apparently widespread on the Northeast Pacific margin and must have influenced the evolution of margin biota and altered biogeochemical cycles with potential feedbacks to global climate change.

• Research Organization: Univ. of California, Santa Barbara, CA (US)
• Sponsoring Organization: US Department of Energy
• OSTI ID: 20003864
• Journal Information: Geology, Journal Name: Geology Journal Issue: 11 Vol. 27; ISSN 0091-7613; ISSN GLGYBA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALIFORNIA
CLIMATIC CHANGE
CONTINENTAL MARGIN
FLUCTUATIONS
GEOCHEMISTRY
OXYGEN