Pronounced changes in carbonate system and temperature history of the Southern California margin from LGM to present

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http://abstractsearch.agu.org/meetings/2012/FM/PP43C-04.html
Author(s): Quintana Krupinski, Nadine B.; Pak, D. K.; Hill, T. M.; Paytan, A.
Author Affiliation(s): Primary:
University of California, Earth and Planetary Sciences, Santa Cruz, CA, United States
Other:
University of California-Santa Barbara, United States
University of California-Davis, United States
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Millennial-scale records of the marine carbonate system and its natural variability provide long-term perspective on anthropogenically-induced ocean acidification, and provide a basis for determining whether there is a critical threshold at which organisms may be negatively affected by changing carbonate saturation and pH. The state, stability and natural variability of pre-anthropogenic marine carbonate systems can be reconstructed from carbonate system proxies in foraminiferal calcite. Using newly calibrated proxies, we quantify the long-term history and variability of the surface water carbonate system in the Southern California Borderland, a coastal region that experiences substantial pH fluctuations today. Our reconstruction of temperature also allows comparison with other nearby Southern California temperature reconstructions. We present trace metal (B/Ca, U/Ca and Mg/Ca), stable isotope (δ18O , δ13C ) and shell weight results from the planktonic foraminifera G. bulloides and N. incompta (N. pachyderma (d)) from Santa Monica Basin (SMB; ODP 1015) to reconstruct the past surface ocean carbonate system and temperature for the past ∼32 ka. We observe a gradual decrease in B/Ca in the thermocline-dwelling N. incompta from 20 ka to ∼12 ka, likely reflecting the decrease in global ocean pH and [CO32-] during deglaciation. Changes in temperature and ocean carbonate chemistry can be observed during the Younger Dryas and Bolling-Allerod in trace metal, stable isotope and shell weight records. Compared with other nearby Southern California ODP sites, temperatures from Mg/Ca during deglaciation in SMB are cooler by ∼1-3 degrees, and show a larger temperature difference between G. bulloides and N. incompta during glacial time than other regional sites. These results strengthen evidence that the southern California Borderland shows a strong atmospheric teleconnection to North Atlantic climate changes, and also provide the opportunity to assess what aspects of southern California records could be regional in nature. Reconstruction of [CO32-] from B/Ca represents a successful application of this proxy for quantifying changes in past ocean carbonate chemistry, and this reconstruction will be placed in context of modern carbonate system variability in the California Current.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; California; Cenozoic; Continental margin; East Pacific; Last glacial maximum; Leg 167; North Pacific; Northeast Pacific; ODP Site 1015; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Quaternary; Santa Monica Basin; Southern California; United States
Coordinates: N334255 N334255 W1184909 W1184909
Record ID: 2014081914
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