Preprints
https://doi.org/10.5194/egusphere-2024-2775
https://doi.org/10.5194/egusphere-2024-2775
25 Sep 2024
 | 25 Sep 2024
Status: this preprint is open for discussion.

New Controls on Sedimentation and Climate in the Central Equatorial Pacific Ocean

Allison W. Jacobel, Kassandra M. Costa, Lily M. Applebaum, and Serena Conde

Abstract. The equatorial Pacific is a nexus of key oceanic and atmospheric phenomena, and its regional climate has critical implications for hydroclimate, the partitioning of CO2, and temperature on a global scale. The spatial complexity of climate signals across the basin has long posed a challenge for interpreting the interplay of different climate phenomena including changes in the Intertropical Convergence Zone (ITCZ) and El Niño Southern Oscillation. Here, we present new, millennially resolved sediment core chronologies and stable isotope records from three sites in the equatorial Pacific’s Line Islands region, as well as updated chronologies for four previously studied cores. Age constraints are derived from 14C (n=17) and δ18O (n=610), which are used as inputs to a Bayesian software package (BIGMACS) that constructs age models and uncertainty bounds via correlation with the global benthic δ18O stack (Lee et al., 2023). We also make use of the new planktonic δ18O data to draw inferences about surface water salinity and to infer a southward-shifted position for the ITCZ at the Last Glacial Maximum (18–24 ka) and Marine Isotope Stage 6 (138–144 ka). These new chronologies and related datasets improve our understanding of equatorial Pacific climate and show strong promise for further surface and deep ocean paleoclimate reconstructions over the last several glacial cycles.

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Allison W. Jacobel, Kassandra M. Costa, Lily M. Applebaum, and Serena Conde

Status: open (until 10 Nov 2024)

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Allison W. Jacobel, Kassandra M. Costa, Lily M. Applebaum, and Serena Conde
Allison W. Jacobel, Kassandra M. Costa, Lily M. Applebaum, and Serena Conde

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Short summary
The equatorial Pacific is an important region that helps determine Earth's climate. This work presents new age models for two sediment core sites located in that region, spanning the last 280 ka. Our age models are based on new radiocarbon dates and oxygen isotope measurements. We also use the oxygen isotope data to infer changes in sea surface salinity patterns, finding evidence for a change in the position of the Intertropical Convergence Zone (ITCZ) on glacial/interglacial timescales.