Calibration of Sr/Ca With Temperature in Sclerosponges
Abstract
Sclerosponges excrete a dense aragonitic skeleton which potentially offer 100's of years of proxy temperature and water chemistry data from a wide range of water depths. Preliminary to a rigorous in situ calibration study in Jamaica, we have used an indirect approach to estimate the relationship between sclerosponge Sr/Ca ratios and temperature. Using laser ablation ICP-MS for Sr/Ca coupled with micromilling for δ 18O , we have produced high-resolution records of both proxies in sclerosponges from the Tongue of the Ocean and Exuma Sound. Because Sr/Ca ratios and δ 18O were significantly correlated, established relations between temperature and oxygen isotopic composition of sclerosponges enabled a preliminary relationship between Sr/Ca and temperature to be determined. Sr/Ca ratios also show a very regular cyclicity, which, if assumed to annual variation reflecting seasonal temperature changes, leads to an age that agrees with U/Th estimates. Sr/Ca records from depths of 67m and 136m reveal that (i) temperature differences between the depths vary on a seasonal scale and (ii) temperature differences between the depths drop to zero on 5-10 year intervals. Using such a method, it can be shown that thermocline depth in Exuma Sound varies seasonally and decadal, reflecting possible decadal scale response of the subtropical Atlantic windfield to atmospheric forcing.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMOS31C0447R
- Keywords:
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- 4267 Paleoceanography;
- 4808 Chemical tracers;
- 4825 Geochemistry;
- 4870 Stable isotopes;
- 4875 Trace elements