HR: 16:30h
AN: PP44A-03    [Abstracts]
TI: Evidence of Stable Middle to Late Holocene Sea Surface Temperatures Along the Baja California Margin
AU: * Coombs, M
EM: coombs@umail.ucsb.edu
AF: University of California, Santa Barbara, Department of Earth Science 552 University Road - Bldg 526, Santa Barbara, CA 93106-9630 United States
AU: Lea, D W
EM: lea@geol.ucsb.edu
AF: University of California, Santa Barbara, Department of Earth Science 552 University Road - Bldg 526, Santa Barbara, CA 93106-9630 United States
AU: Herguera, J
EM: herguera@cicese.mx
AF: Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Division de Oceanologia Km 107, Carretera Tijuana Ensenada, Ensenada, BC 22860 Mexico
AB: Climate variability within the Holocene epoch can be considered the standard against which we compare present climate variability. Here we present paleo-sea surface temperatures from ~3600 B.C.E. to 2000 C.E. (i.e., middle Holocene to present) as recorded in Mg/Ca and d18O performed on planktonic foraminiferal species Globigerina bulloides and Globigerinoides ruber from marine sediments. The chosen site of study - San Lazaro Basin, Baja California Sur, Mexico - is particularly sensitive to climatic and oceanographic forcings from both the temperate and the tropical to equatorial Pacific Ocean because of its location beneath the dynamic boundary between the cool northern California Current waters and the warmer southern tropical waters. Four separate proxies (Mg/Ca and d18O on two planktonic foraminiferal species) indicate that sea surface temperatures (SSTs) along the Baja California continental margin were relatively stable between ~3600 B.C.E. and 1600 C.E. G. bulloides Mg/Ca SSTs for this period ranged between 19 and 26 deg C, with a mean of 21.5 +/-1.5 deg C (1 standard deviation). G. ruber Mg/Ca SSTs ranged between 20 and 27 deg C, with a mean of 22.8 +/- 1.4 (1 standard deviation). Mg/Ca SST results from a core (PCM00-78C) representing ~1850-2000 C.E. show Mg/Ca SSTs between 1950 and 2000 that ranged between ~20 and 23 deg C; instrumental mean annual SSTs for this same period were between 19 and 23 deg C, indicating that Mg/Ca is a valid indicator of paleo-temperature in this region. In addition, we will present Mg/Ca data from an additional core (BAP96-6K) that represents the period ~1000-1900 C.E.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4944 Micropaleontology (0459, 3030)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005