Correlation of marine and coastal terrestrial records of central California: Response to paleoceanographic and paleoclimatic change during the past 19,000 years

Abstract

New benthic foraminiferal census data combined with previously published planktic foraminiferal and pollen data from the continental margin off central California provide a unique opportunity to document concurrent paleoceanographic and paleoclimatic changes in the region during the late Quaternary. All three datasets were evaluated in gravity core S3-15G, collected at a depth of 3491 on the western levy of the Monterey Fan (36°23.53′N, 123°20.52′W). Accelerator mass spectrometry radiocarbon dates and the ratio of the planktic foraminiferal species Neogloboquardrina pachyderma (Ehrenberg) to Neogloboquadrina incompta (Cifelli) provide a good age-depth model for the last 19,000 years, covering the last glacial, Bølling–Allerød, Younger Dryas, and Holocene intervals. Separate Q-mode cluster analyses of the hemipelagic as well as mixed (combined hemipelagic and turbiditic) mud samples grouped the benthic foraminiferal fauna into two clusters reflecting faunal adaptation to changing climatic conditions during the Pleistocene and Holocene. R-mode cluster analysis also differentiated glacial (Uvigerina senticosa and Globobulimina auriculata) and interglacial (Melonis pompilioides and Gyroidina planulata) faunas. A general trend of slightly increasing oxygen in the deep sea is suggested from the Pleistocene to Holocene based on the reduction in abundance of G. auriculata and increased frequency of M. pompilioides. Q-mode cluster analysis of the planktic foraminifera illustrates a change in the surface water from a glacial subpolar fauna in the Pleistocene to a transitional fauna in the Holocene, whereas the pollen record separated into three clusters, two of Pleistocene age (glacial and transitional) and one in the Holocene (interglacial), reflecting the terrestrial floral adaptation in the California Coast Ranges of central California to the warmer climate in the Holocene. Decoupling is evident between the benthic and planktic foraminiferal and terrestrial floral responses to changing oceanographic and climatic conditions. The floral response leads the surface-dwelling fauna by several millennia, and is followed by the deep-dwelling benthic foraminiferal fauna a millennium later.