Seasonally Variable Aquifer Discharge and Cooler Climate in Bermuda During the Last Interglacial Revealed by Subannual Clumped Isotope Analysis
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 of Cittarium pica fossil shells supporting previous findings of cooler tha...
| Published in: | Paleoceanography and Paleoclimatology |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Wiley Periodicals, Inc.
2021
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| Subjects: | |
| Online Access: | https://hdl.handle.net/2027.42/167776 https://doi.org/10.1029/2020PA004145 |
| Summary: | 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 of Cittarium pica fossil shells supporting previous findings of cooler than modern temperatures in Bermuda during the Last Interglacial. We resolve temperature and δ18Ow differences between two closely located and apparently coeval sites described in Winkelstern et al. (2017), https://doi.org/10.1002/2016pa003014 through reprocessing raw isotopic data with the updated Brand/IUPAC parameters. New subannual‐resolution clumped isotope data reveal large variations in δ18Ow out of phase with seasonal temperature changes (i.e., lower δ18Ow values in winter). Supported by modern δ18Ow measurements identifying similar processes occurring today, we suggest past variations in coastal δ18Ow were driven by seasonally variable freshwater discharge from a subterranean aquifer beneath the island. Taken together, our results emphasize the importance of δ18Ow in controlling carbonate δ18O, and suggest that typical assumptions of constant δ18Ow should be made cautiously in nearshore settings and can contribute to less accurate reconstructions of paleotemperature.Key PointsBermudan climate during the Last Interglacial period (MIS 5e) was colder than todaySubannual clumped isotope analyses capture seasonal‐scale changes in temperature and water compositionVariable discharge from an underground aquifer affects oxygen isotopic composition of coastal water during MIS 5e and today Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/167776/1/palo21033_am.pdf http://deepblue.lib.umich.edu/bitstream/2027.42/167776/2/palo21033.pdf http://deepblue.lib.umich.edu/bitstream/2027.42/167776/3/2020PA004145-sup-0001-Supporting_Information_SI-S01.pdf |
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