High-Resolution Foraminiferal, Isotopic, and Trace Element Records from Holocene Estuarine Deposits of San Francisco Bay, California

摘要

A 3.5-m gravity core (DJ6-93SF-6) from San Francisco Bay reveals a complex paleoclimatic history of the region over the last 3870 cal YBP. A polynomial equation based on 11 AMS 14C ages provides an excellent age model for the core, and environmental proxies for water temperature and salinity are derived from various foraminiferal abundances, stable carbon and oxygen isotopes, and Mg/Ca ratios. Two foraminiferal associations were identified by Q-mode cluster analysis: a colder-water Elphidium excavatum association and the warmer-water Ammonia beccarii–Elphidium gunteri association. The E. excavatum association dominates the core for all but about 600 years out of the last four millennia.