Bottom-water oxygenation and environmental change in Santa Monica Basin, Southern California during the last 23 kyr

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doi: 10.1016/j.palaeo.2017.09.002
Author(s): Balestra, Barbara; Quintana Krupinski, Nadine B.; Erohina, Tzvetina; Fessenden-Rahn, Julianna; Rahn, Thom; Paytan, Adina
Author Affiliation(s): Primary:
University of California at Santa Cruz, Institute of Marine Science, Santa Cruz, CA, United States
Los Alamos National Laboratory, United States
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Vol.490, p.17-37. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. Includes appendix. 81 refs.; illus., incl. 5 tables, sketch map
Summary: The Southern California Borderland is a region that experiences strong natural variations in bottom water oxygen and pH. We use marine sediments from Santa Monica Basin to reconstruct environmental conditions in the basin's bottom water from the Last Glacial Maximum (LGM) to present. We then compare the records to the adjacent Santa Barbara Basin and Santa Lucia Slope. High-resolution records of benthic foraminiferal oxygen and carbon isotopes (δ18O and δ13C), benthic foraminiferal assemblages, and bulk sedimentary organic matter geochemistry records exhibit major changes associated with late Quaternary millennial-scale global climate oscillations. Our data show the dominance of low-oxygen benthic foraminiferal assemblages during warm intervals, and assemblages representing higher dissolved oxygen during cooler intervals, as also seen in Santa Barbara Basin and Santa Lucia Slope. However, our record shows a stronger and longer-lasting oxygen minimum zone (OMZ) between the mid Younger Dryas (YD) and the Early Holocene than at neighboring sites, indicated by dominance of Bolivina tumida (characteristic of major hypoxia) in the assemblage. The middle to late Holocene (from ∼ 9 to 0 kyr) had weaker hypoxia than the early Holocene, with assemblages mainly composed of Bolivina argentea and Uvigerina peregrina. Santa Monica Basin remained slightly hypoxic throughout the past 23 kyr, however, differences in the degree of hypoxia from Santa Barbara Basin and Santa Lucia Slope (especially from the B-A to the Early Holocene) are seen. The Santa Monica Basin bottom water is affected by regional processes, such as changes in the source of intermediate water and/or changing ventilation (oxygenation) of the intermediate water source. This is due to the greater depth and the more southern geographic position of the Basin, which reduces exposure to the oxygenated North Pacific Intermediate Water current. Additional local processes also affect the basin, such as the effects of sediment influx from submarine canyons. This analysis utilizing parallel geochemical and micropaleontological records brings new insights into bottom water and climate conditions in Santa Monica Basin, indicating regional similarities and differences from adjacent basins, and provides insight into the causes for changes in bottom water oxygenation.
Year of Publication: 2018
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Assemblages; Benthic taxa; Bolivina; Bolivina argentea; Bolivina tumida; Bolivinitidae; Bottom water; Buliminacea; C-13/C-12; California; Carbon; Cenozoic; Climate change; Continental borderland; Continental slope; Cores; Dysaerobic environment; East Pacific; Foraminifera; Geochemistry; Glacial environment; Holocene; Hydrochemistry; Interglacial environment; Isotope ratios; Isotopes; Last glacial maximum; Leg 146; Leg 167; Lower Holocene; Marine sediments; Microfossils; N-15/N-14; Nitrogen; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 1015; ODP Site 893; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleoclimatology; Pleistocene; Quaternary; Rotaliina; Santa Barbara Basin; Santa Lucia Slope; Santa Monica Basin; Sediments; Southern California; Stable isotopes; United States; Upper Pleistocene; Upper Weichselian; Uvigerina; Uvigerina peregrina; Uvigerinidae; Weichselian; Younger Dryas
Coordinates: N334255 N334255 W1184909 W1184909
Record ID: 2018025378
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands