A Lacustrine Carbonate Record of Holocene Seasonality and Climate

Authors

Chad A. Wittkop, Department of Chemistry and Geology, Minnesota State University, Mankato, Minnesota 56001, USAFollow
Jane L. Teranes, Scripps Institution of Oceanography, Geologic Research Division, University of California–San Diego, 9500 Gilman Drive, La Jolla, California 92093-0244, USA
Walter E. Dean, U.S. Geological Survey, Earth Surface Processes, Box 25046, MS 980, Federal Center, Denver, Colorado 80225, USA
Thomas P. Guilderson, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, P.O. Box 808, L-397, Livermore, California 94550, USA

Document Type

Article

Date of this Version

2009

Comments

Published in Geology, August 2009; v. 37; no. 8; p. 695–698.

Abstract

Annually laminated (varved) Holocene sediments from Derby Lake, Michigan, display variations in endogenic calcite abundance refl ecting a long-term (millennial-scale) decrease in burial punctuated with frequent short-term (decadal-scale) oscillations due to carbonate dissolution. Since 6000 cal yr B.P., sediment carbonate abundance has followed a decreasing trend while organic-carbon abundance has increased. The correlation between organic-carbon abundance and the sum of March-April-October-November insolation has an r² value of 0.58. We interpret these trends to represent a precession-driven lengthening of the Holocene growing season that has reduced calcite burial by enhancing net annual organic-matter production and associated calcite dissolution. Correlations with regional paleoclimate records suggest that changes in temperature and moisture balance have impacted the distribution of short-term oscillations in carbonate and organic-matter abundance superimposed on the precession-driven trends.