VARIATIONS IN THE OXYGEN MINIMUM ZONE IN THE GUAYMAS BASIN, GULF OF CALIFORNIA DURING THE PAST 15,000 YEARS

Analysis of the benthic foraminiferal fauna in the JPC-56 core, western Guaymas Basin, indicates that variations in the foraminiferal faunas during the past 15,000 yrs correlate with the global and local climatic events. The expansion and contraction of the Pacific Intermediate Water mass and the oxygen minimum zone in the Gulf of California directly correlates with a warm North Pacific (expansion) and/or a cool North Pacific (contraction). An expanded or more intense oxygen minimum zone is noted in the Bølling/Allerød and early Holocene intervals, whereas a contracted or less intense oxygen minimum zone is noted in the Younger Dryas and middle to late Holocene intervals. The faunas in JPC-56 also suggest that during cool events in the southern Pacific, the quantity of Pacific Deep Water in the Gulf of California expands. Increased quantities of Pacific Deep Water are observed in the Younger Dryas and middle to late Holocene intervals. The foraminiferal faunas in JPC-56 correlate with local climatic events such as the mid-Holocene drought Altithermal which affected the southwestern United States from about 7 to 5 ka.