Stable Isotope Stratigraphy of Regional Environmental Dynamics from Lacustrine Archives

Kerry K. Kelts and Antje Schwalb

The quest for long sequences of high-resolution paleoclimate will increasingly utilize the aqueous stable isotopic tracers from lake deposits of all ages to unravel paleogeographic patterns. The tool is powerful when examining the relative threshold dynamics of a lake system, in particular switchovers of open and closed basin hydrology. Quirks of this tool however require precise understanding of what climate parameters are stored, and the component habitat, sediment subenvironments and specific lacustrine type.

We briefly survey advantages and pitfalls of a systems approach to interpretations which couples oxygen and carbon isotopic results with sedimentology of biotic and abiotic carbonate components of modern lakes. Cross plots of Kelts ^dgrv¹³C/^dgrv¹⁸O help discriminate airmass evolution, evaporation history and hydrologic shifts. Many records provide isotopic evidence of a unique feature of lake systems to evolve as sources of carbon dioxide. Comparative examples include signatures from Lakes Neuchatel and Zurich, various midwestern settings, and a compilation of numerous saline lake sequences around the world.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California