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.