Using Atlantic Sediment Cores to Evaluate Na/Ca ratios in T. sacculifer as a Paleosalinity Proxy
Abstract
Recent culturing studies found a significant positive correlation between seawater salinity and the incorporation of Na into foraminiferal calcite, suggesting a potential new proxy for reconstructing past changes in sea surface salinity (SSS) (Bertlich et al.,2018). We test the applicability of this new proxy in sediment samples by measuring Na/Ca ratios in the planktic foraminifera Trilobatus sacculifer from 10 Atlantic core tops across a natural salinity gradient, spanning the northern to southern gyres and more than 2 units of salinity variability. Initial results from three size fractions (250 - 355 μm, 355 - 425 μm and > 425 μm) show higher Na/Ca ratios in the gyre regions and lower ratios in the fresher equatorial regions, suggesting SSS is a primary control in Na incorporation in the species. We will also present a high-resolution downcore SSS record based on Na/Ca ratios in T. sacculifer from Florida Straits core 26JPC and compare the resulting record with previous reconstructions of past salinity change based on the calculation of δ18Oseawater from Mg/Ca-SST and δ18O measurements and from Ba/Ca ratios in a near surface dwelling planktonic foraminifera (Schmidt and Lynch Stieglitz, 2011). Our data is expected to further develop and constrain the Na/Ca- SSS proxy.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP12B..06W
- Keywords:
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- 0419 Biomineralization;
- BIOGEOSCIENCES;
- 0454 Isotopic composition and chemistry;
- BIOGEOSCIENCES;
- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 4994 Instruments and techniques;
- PALEOCEANOGRAPHY