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Title: Bottom-water oxygenation and environmental change in Santa Monica Basin, southern California during the last 22 kyr

Abstract

The Southern California Borderland (SCB) is a region that experiences strong natural variations in bottom water oxygen and pH. Here, we use marine sediments from the Santa Monica Basin (SMB) to reconstruct environmental conditions and changes in the basin's bottom water oxygenation from the Last Glacial Maximum (LGM) to present, and compare the records to the adjacent Santa Barbara Basin (SBB) and Santa Lucia Slope (SLS). High-resolution records of benthic foraminiferal oxygen and carbon isotopes (δ 18O and δ 13C), 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 foraminifera assemblages during warm intervals, and assemblages representing higher dissolved oxygen during cooler intervals, as also seen in SBB and SLS. But, our record shows a stronger and longer-lasting oxygen minimum zone (OMZ) between the end of the Bølling-Allerød (B-A) and the Early Holocene (including the Younger Dryas) than at neighboring sites, indicated by dominance of Bolivina tumida (characteristic of major hypoxia) in the assemblage. The middle to late Holocene (from ~ 8.8 to 0 ka) had weaker hypoxia than the early Holocene, with assemblages mainly composed of Bolivina argentea andmore » Uvigerina peregrina. The SMB remains mostly slightly low in oxygen throughout the studied interval, with differences in the degree of hypoxia relative to SBB and SLS (especially from the B-A to the Early Holocene) likely due to its greater depth and its more southern geographic position and therefore decreased exposure to North Pacific Intermediate Water current. Regional effects, such as changing intermediate water source and/or changing ventilation (oxygenation) of the intermediate water source, also affect SMB deep water. Our analysis utilizing parallel geochemical and micropaleontological records brings new insights into bottom water and climate conditions in SMB, indicating regional similarities and differences with adjacent basins, and provides insight into the causes for changes in bottom water oxygenation.« less

Authors:
 [1];  [2];  [1]; ORCiD logo [3];  [3];  [1]
  1. Univ. of California, Santa Cruz, CA (United States). Inst. of Marine Science
  2. Univ. of California, Santa Cruz, CA (United States). Inst. of Marine Science; Lund Univ. (Sweden). Dept. of Geology
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1398937
Report Number(s):
LA-UR-17-28251
Journal ID: ISSN 0031-0182
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Accepted Manuscript
Journal Name:
Palaeogeography, Palaeoclimatology, Palaeoecology
Additional Journal Information:
Journal Volume: 490; Journal ID: ISSN 0031-0182
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Analytical Chemistry; Earth Sciences; climate science, paleoclimate

Citation Formats

Balestra, Barbara, Krupinksi, Nadine Quintana, Erhoina, Tzvetina, Fessenden-Rahn, Julianna, Rahn, Thom, and Paytan, Adina. Bottom-water oxygenation and environmental change in Santa Monica Basin, southern California during the last 22 kyr. United States: N. p., 2017. Web. doi:10.1016/j.palaeo.2017.09.002.
Balestra, Barbara, Krupinksi, Nadine Quintana, Erhoina, Tzvetina, Fessenden-Rahn, Julianna, Rahn, Thom, & Paytan, Adina. Bottom-water oxygenation and environmental change in Santa Monica Basin, southern California during the last 22 kyr. United States. doi:10.1016/j.palaeo.2017.09.002.
Balestra, Barbara, Krupinksi, Nadine Quintana, Erhoina, Tzvetina, Fessenden-Rahn, Julianna, Rahn, Thom, and Paytan, Adina. Fri . "Bottom-water oxygenation and environmental change in Santa Monica Basin, southern California during the last 22 kyr". United States. doi:10.1016/j.palaeo.2017.09.002. https://www.osti.gov/servlets/purl/1398937.
@article{osti_1398937,
title = {Bottom-water oxygenation and environmental change in Santa Monica Basin, southern California during the last 22 kyr},
author = {Balestra, Barbara and Krupinksi, Nadine Quintana and Erhoina, Tzvetina and Fessenden-Rahn, Julianna and Rahn, Thom and Paytan, Adina},
abstractNote = {The Southern California Borderland (SCB) is a region that experiences strong natural variations in bottom water oxygen and pH. Here, we use marine sediments from the Santa Monica Basin (SMB) to reconstruct environmental conditions and changes in the basin's bottom water oxygenation from the Last Glacial Maximum (LGM) to present, and compare the records to the adjacent Santa Barbara Basin (SBB) and Santa Lucia Slope (SLS). 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 foraminifera assemblages during warm intervals, and assemblages representing higher dissolved oxygen during cooler intervals, as also seen in SBB and SLS. But, our record shows a stronger and longer-lasting oxygen minimum zone (OMZ) between the end of the Bølling-Allerød (B-A) and the Early Holocene (including the Younger Dryas) than at neighboring sites, indicated by dominance of Bolivina tumida (characteristic of major hypoxia) in the assemblage. The middle to late Holocene (from ~ 8.8 to 0 ka) had weaker hypoxia than the early Holocene, with assemblages mainly composed of Bolivina argentea and Uvigerina peregrina. The SMB remains mostly slightly low in oxygen throughout the studied interval, with differences in the degree of hypoxia relative to SBB and SLS (especially from the B-A to the Early Holocene) likely due to its greater depth and its more southern geographic position and therefore decreased exposure to North Pacific Intermediate Water current. Regional effects, such as changing intermediate water source and/or changing ventilation (oxygenation) of the intermediate water source, also affect SMB deep water. Our analysis utilizing parallel geochemical and micropaleontological records brings new insights into bottom water and climate conditions in SMB, indicating regional similarities and differences with adjacent basins, and provides insight into the causes for changes in bottom water oxygenation.},
doi = {10.1016/j.palaeo.2017.09.002},
journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
number = ,
volume = 490,
place = {United States},
year = {2017},
month = {9}
}

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