Application of Clumped-Isotope Thermometry to Paleotemperature Reconstruction from Lacustrine Carbonates
Abstract
Clumped-isotope thermometry (Eiler, 2007) is a novel method for paleotemperature determination based on the measurement of the abundance of 13C-18O bonds in carbonates. Gosh et al. (2006) have shown that the formation of 13C-18O bonds in carbonates is temperature dependent and the difference from the measured abundance compared to a stochastic isotope distribution can be related to the temperature of formation of the carbonate. With this method it is possible to obtain a temperature estimate that can be used in combination with the δ18O of the carbonate to reconstruct the oxygen isotope composition of the water. We will present first data obtained from the application of clumped-isotope thermometry to lacustrine carbonates from Lake Zurich. Lacustrine carbonates, because of their wide distribution, are important archives of climate change on the continents. However, the extraction of climatic information from carbonate oxygen isotope records is hampered by the dependency of δ18O of carbonates from both the temperature and the isotopic composition of the lake water. Clumped-isotope thermometry has the capability to solve this long standing problem. We are evaluating the potential of the method by analyzing Lake Zurich sediments and comparing it with historical water temperature measurements for the last 60 years. We have analyzed samples from a short core collected at the deepest point of the lake and annual varves were sampled from the years 1901 to 2000. We will show a comparison from the annual mean temperature of the Lake Zurich surface water derived by clumped-isotope thermometry from measured varves compared to recorded temperatures as well as first data from the authigenic carbonates, precipitated during 2008 in the surface water of Lake Zurich. Eiler, J. M., 2007. Clumped-isotope geochemistry - The study of naturally-occurring, multiply-substituted isotopologues. EPSL 262, 309-327. Ghosh, P., Adkins, J., Affek, H., Balta, B., Guo, W., Schauble, E. A., Schrag, D., and Eiler, J. M., 2006. 13C-18O bonds in carbonate minerals: A new kind of paleothermometer. GCA 70, 1439-1456.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMPP21B1427S
- Keywords:
-
- 1041 Stable isotope geochemistry (0454;
- 4870);
- 4942 Limnology (0458;
- 1845;
- 4239)