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Title: Seasonally Variable Aquifer Discharge and Cooler Climate in Bermuda During the Last Interglacial Revealed by Subannual Clumped Isotope Analysis
Abstract

Faunal analog reconstructions suggest that Last Interglacial (MIS 5e) sea surface temperatures were cooler around Bermuda and in the Caribbean than modern climate. Here we describe new and revised clumped isotope measurements ofCittarium picafossil shells supporting previous findings of cooler than modern temperatures in Bermuda during the Last Interglacial. We resolve temperature and δ18Owdifferences between two closely located and apparently coeval sites described in Winkelstern et al. (2017),https://doi.org/10.1002/2016pa003014through reprocessing raw isotopic data with the updated Brand/IUPAC parameters. New subannual‐resolution clumped isotope data reveal large variations in δ18Owout of phase with seasonal temperature changes (i.e., lower δ18Owvalues in winter). Supported by modern δ18Owmeasurements identifying similar processes occurring today, we suggest past variations in coastal δ18Owwere driven by seasonally variable freshwater discharge from a subterranean aquifer beneath the island. Taken together, our results emphasize the importance of δ18Owin controlling carbonate δ18O, and suggest that typical assumptions of constant δ18Owshould be made cautiously in nearshore settings and can contribute to less accurate reconstructions of paleotemperature.

 
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Award ID(s):
1903237 1903389
NSF-PAR ID:
10449378
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Paleoceanography and Paleoclimatology
Volume:
36
Issue:
6
ISSN:
2572-4517
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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