Intermittent existence of a southern Californian upwelling cell during submillennial climate change of the last 60 kyr

Abstract

Application of a high-resolution multiproxy approach to a sedimentary section drilled at Ocean Drilling Program Site 1017, located under a highly active upwelling cell off Point Conception, California, provides clear evidence for surface ocean productivity shifts on submillennial timescales during the last 60 kyr. The proxies include bulk-sediment major and minor elements, organic carbon and carbonate concentrations, δ15N, and planktonic foraminiferal species assemblage and carbon isotope determinations. The collective results demonstrate that marine productivity in this area was not simply linearly related to cold and warm cycles except during the millennial-scale climate oscillations of marine isotope stage (MIS) 3. During that interval, the upwelling cell and resulting high productivity were active during warm interstadial events and were largely inactive during cool stadial events. However, the Last Glacial Maximum was also relatively productive. Productivity increased dramatically during the Bø lling warm interval, while the Ållerød and Younger Dryas were much less productive. High coccolithophorid abundance commenced during the earliest Holocene after 10 ka. The complexity of the productivity response was probably related to interplay between local winds, as well as California Undercurrent strength. Copyright 2004 by the American Geophysical Union.