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Title: A Bayesian, multivariate calibration for Globigerinoides ruberMg/Ca

Abstract

The use of Mg/Ca in marine carbonates as a paleothermometer has been challenged by observations that implicate salinity as a contributing influence on Mg incorporation into biotic calcite and that dissolution at the sea-floor alters the original Mg/Ca. Yet, these factors have not yet been incorporated into a single calibration model. In this paper, we introduce a new Bayesian calibration for Globigerinoides ruber Mg/Ca based on 186 globally distributed core top samples, which explicitly takes into account the effect of temperature, salinity, and dissolution on this proxy. Our reported temperature, salinity, and dissolution (here expressed as deep-water ΔCO 2- 3) sensitivities are (±2σ) 8.7±0.9%/°C, 3.9±1.2%/psu, and 3.3±1.3%/μmol.kg -1 below a critical threshold of 21 μmol/kg in good agreement with previous culturing and core-top studies. We then perform a sensitivity experiment on a published record from the western tropical Pacific to investigate the bias introduced by these secondary influences on the interpretation of past temperature variability. This experiment highlights the potential for misinterpretations of past oceanographic changes when the secondary influences of salinity and dissolution are not accounted for. Finally, multiproxy approaches could potentially help deconvolve the contributing influences but this awaits better characterization of the spatio-temporal relationship between salinity andmore » δ 18O sw over millennial and orbital timescales.« less

Authors:
 [1];  [2];  [3];  [4];  [4]
  1. Univ. of Texas, Austin, TX (United States). Inst. for Geophysics; Univ. of Southern California, Los Angeles, CA (United States). Dept. of Earth Science
  2. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Mathematics and Statistics
  3. Univ. of Texas, Austin, TX (United States). Inst. for Geophysics
  4. Univ. of Southern California, Los Angeles, CA (United States). Dept. of Earth Science
Publication Date:
Research Org.:
Univ. of Texas, Austin, TX (United States); Univ. of New Mexico, Albuquerque, NM (United States); Univ. of Southern California, Los Angeles, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Science Foundation (NSF)
OSTI Identifier:
1454911
Grant/Contract Number:  
SC0006985; SC0010843; ATM-0902507; DMS1025464
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Geochemistry, Geophysics, Geosystems
Additional Journal Information:
Journal Volume: 16; Journal Issue: 9; Journal ID: ISSN 1525-2027
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 97 MATHEMATICS AND COMPUTING; Mg/Ca calibration; Bayesian statistics

Citation Formats

Khider, D., Huerta, G., Jackson, C., Stott, L. D., and Emile-Geay, J. A Bayesian, multivariate calibration for Globigerinoides ruberMg/Ca. United States: N. p., 2015. Web. doi:10.1002/2015GC005844.
Khider, D., Huerta, G., Jackson, C., Stott, L. D., & Emile-Geay, J. A Bayesian, multivariate calibration for Globigerinoides ruberMg/Ca. United States. doi:10.1002/2015GC005844.
Khider, D., Huerta, G., Jackson, C., Stott, L. D., and Emile-Geay, J. Wed . "A Bayesian, multivariate calibration for Globigerinoides ruberMg/Ca". United States. doi:10.1002/2015GC005844. https://www.osti.gov/servlets/purl/1454911.
@article{osti_1454911,
title = {A Bayesian, multivariate calibration for Globigerinoides ruberMg/Ca},
author = {Khider, D. and Huerta, G. and Jackson, C. and Stott, L. D. and Emile-Geay, J.},
abstractNote = {The use of Mg/Ca in marine carbonates as a paleothermometer has been challenged by observations that implicate salinity as a contributing influence on Mg incorporation into biotic calcite and that dissolution at the sea-floor alters the original Mg/Ca. Yet, these factors have not yet been incorporated into a single calibration model. In this paper, we introduce a new Bayesian calibration for Globigerinoides ruber Mg/Ca based on 186 globally distributed core top samples, which explicitly takes into account the effect of temperature, salinity, and dissolution on this proxy. Our reported temperature, salinity, and dissolution (here expressed as deep-water ΔCO2-3) sensitivities are (±2σ) 8.7±0.9%/°C, 3.9±1.2%/psu, and 3.3±1.3%/μmol.kg-1 below a critical threshold of 21 μmol/kg in good agreement with previous culturing and core-top studies. We then perform a sensitivity experiment on a published record from the western tropical Pacific to investigate the bias introduced by these secondary influences on the interpretation of past temperature variability. This experiment highlights the potential for misinterpretations of past oceanographic changes when the secondary influences of salinity and dissolution are not accounted for. Finally, multiproxy approaches could potentially help deconvolve the contributing influences but this awaits better characterization of the spatio-temporal relationship between salinity and δ18Osw over millennial and orbital timescales.},
doi = {10.1002/2015GC005844},
journal = {Geochemistry, Geophysics, Geosystems},
issn = {1525-2027},
number = 9,
volume = 16,
place = {United States},
year = {2015},
month = {7}
}

Journal Article:
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