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- Title
Glacial-interglacial sea water isotope change near the Chilean Margin as reflected by d²H of C37 alkenones.
- Authors
Hättig, Katrin; Varma, Devika; Schouten, Stefan; van der Meer, Marcel T. J.
- Abstract
Hydrogen isotopic compositions of C37 long chain alkenones (d2HC37) have been proposed as a proxy for past seawater salinity and applied in several regions. However, previous studies were based solely on a single core and often suggested unlikely large changes in salinity. Here we present a new d2HC37 record, in combination with oxygen isotopes of benthic foraminifera from the same samples, from a sediment core from the Chilean Margin (ODP site 1235). The observed negative shift in d2HC37 of 20‰ during deglaciation was identical to that of the nearby located, but deeper, ODP core 1234, suggesting a regionally consistent shift in d2HC37. This shift translates into a hydrogen isotope shift of the surface seawater (Δδ2HSW) of ca. 14‰, similar to glacial-interglacial reconstructions based on other d2HC37 records. The reconstructed bottom seawater oxygen isotope change based on benthic foraminifera during the last deglaciation is approximately 0.8‰, in line with previous studies. When translated into ‰δ2HSW using the modern open-ocean waterline this would suggest a shift of ca. 5‰, smaller than the reconstructed surface seawater shift based on alkenones. The higher change in surface d2HSW suggests that the surface water experienced more freshening during the Holocene than bottom waters either due to increased freshwater input or reduced evaporation, or a combination of the two.
- Subjects
SEAWATER; ISOTOPE shift; OXYGEN isotopes; HYDROGEN isotopes; ISOTOPES
- Publication
Climate of the Past Discussions, 2023, p1
- ISSN
1814-9324
- Publication type
Article
- DOI
10.5194/egusphere-2023-1042