Quantified intermediate water oxygenation history of the NE Pacific: A new benthic foraminiferal record from Santa Barbara basin
Article first published online: 30 AUG 2013
©2013. American Geophysical Union. All Rights Reserved.
Volume 28, Issue 3, pages 453–467, September 2013
How to Cite
2013), Quantified intermediate water oxygenation history of the NE Pacific: A new benthic foraminiferal record from Santa Barbara basin, Paleoceanography, 28, 453–467, doi:10.1002/palo.20043., , , , , , , and (
- Issue published online: 11 OCT 2013
- Article first published online: 30 AUG 2013
- Accepted manuscript online: 30 JUL 2013 10:12AM EST
- Manuscript Accepted: 26 JUL 2013
- Manuscript Revised: 22 JUL 2013
- Manuscript Received: 3 MAY 2012
- U.S. National Science Foundation. Grant Number: OCE-0825322 and 0825366
- oxygen minimum zone;
- oxygen index;
The oxygen minimum zone (OMZ) of the late Quaternary California margin experienced abrupt and dramatic changes in strength and depth in response to changes in intermediate water ventilation, ocean productivity, and climate at orbital through millennial time scales. Expansion and contraction of the OMZ is exhibited at high temporal resolution (107–126 year) by quantitative benthic foraminiferal assemblage changes in two piston cores forming a vertical profile in Santa Barbara Basin (569 m, basin floor; 481 m, near sill depth) to 34 and 24 ka, respectively. Variation in the OMZ is quantified by new benthic foraminiferal groupings and new dissolved oxygen index based on documented relations between species and water-mass oxygen concentrations. Foraminiferal-based paleoenvironmental assessments are integrated with principal component analysis, bioturbation, grain size, CaCO3, total organic carbon, and δ13C to reconstruct basin oxygenation history. Fauna responded similarly between the two sites, although with somewhat different magnitude and taxonomic expression. During cool episodes (Younger Dryas and stadials), the water column was well oxygenated, most strongly near the end of the glacial episode (17–16 ka; Heinrich 1). In contrast, the OMZ was strong during warm episodes (Bølling/Allerød, interstadials, and Pre-Boreal). During the Bølling/Allerød, the OMZ shoaled to <360 m of contemporaneous sea level, its greatest vertical expansion of the last glacial cycle. Assemblages were then dominated by Bolivina tumida, reflecting high concentrations of dissolved methane in bottom waters. Short decadal intervals were so severely oxygen-depleted that no benthic foraminifera were present. The middle to late Holocene (6–0 ka) was less dysoxic than the early Holocene.