TY - JOUR
T1 - Implications of seawater Mg/Ca variability for Plio-Pleistocene tropical climate reconstruction
AU - Medina-Elizalde, Martín
AU - Lea, David W.
AU - Fantle, Matthew S.
N1 - Funding Information:
This material is based upon the work supported by the National Science Foundation under Grant No. OCE0502609. Additional support was provided by CONACYT-UCMEXUS. We thank Alan Haywood and two anonymous reviewers for their comments and suggestions. We also thank Kira Lawrence, Katharina Billups, Howard Spero, Petra Dekens and Christina Ravelo for valuable discussions of our work.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2008/5/30
Y1 - 2008/5/30
N2 - Recent reconstructions of Mg and Ca concentrations of seawater indicate that seawater Mg/Ca changed significantly over the last 5 million years (Ma). Tropical sea surface temperature (SST) records for the last 5 Ma based on foraminiferal Mg/Ca paleothermometry assume constant seawater Mg/Ca. These SST records suggest that average equatorial Pacific SSTs remained thermally stable from 5 to 2 Ma, after which significant cooling occurred only in the eastern equatorial Pacific. This study examines the implications of adjusting available equatorial Pacific SST records based on Mg/Ca paleothermometry to account for the inferred past variations of seawater Mg/Ca. The results suggest that both the cold and the warm regions of the equatorial Pacific were much warmer during the early Pliocene (30-31 °C), and that both regions experienced a marked cooling from ∼ 4 Ma to ∼ 1 Ma. This new interpretation of foraminiferal Mg/Ca creates a discrepancy with alkenone unsaturation-based SST records from the eastern equatorial Pacific, which might be due to either overestimation of changes in past seawater Mg/Ca or to factors affecting the interpretation of the UK' 37 index. The adjusted SST records are consistent with the hypothesis that higher levels of greenhouse gases maintained the warmth of the early Pliocene.
AB - Recent reconstructions of Mg and Ca concentrations of seawater indicate that seawater Mg/Ca changed significantly over the last 5 million years (Ma). Tropical sea surface temperature (SST) records for the last 5 Ma based on foraminiferal Mg/Ca paleothermometry assume constant seawater Mg/Ca. These SST records suggest that average equatorial Pacific SSTs remained thermally stable from 5 to 2 Ma, after which significant cooling occurred only in the eastern equatorial Pacific. This study examines the implications of adjusting available equatorial Pacific SST records based on Mg/Ca paleothermometry to account for the inferred past variations of seawater Mg/Ca. The results suggest that both the cold and the warm regions of the equatorial Pacific were much warmer during the early Pliocene (30-31 °C), and that both regions experienced a marked cooling from ∼ 4 Ma to ∼ 1 Ma. This new interpretation of foraminiferal Mg/Ca creates a discrepancy with alkenone unsaturation-based SST records from the eastern equatorial Pacific, which might be due to either overestimation of changes in past seawater Mg/Ca or to factors affecting the interpretation of the UK' 37 index. The adjusted SST records are consistent with the hypothesis that higher levels of greenhouse gases maintained the warmth of the early Pliocene.
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U2 - 10.1016/j.epsl.2008.03.014
DO - 10.1016/j.epsl.2008.03.014
M3 - Article
AN - SCOPUS:43249125407
SN - 0012-821X
VL - 269
SP - 585
EP - 595
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 3-4
ER -