Isotopic composition of river waters and early stage carbonates crusts along an elevation transect at 33 degrees south latitude, southern central Andes

HOKE G. D.; WILLIAMS K. J.; GARZIONE C. N.; ARANEO D. C.; STRECKER M. R.

San Francisco, California, EEUU

Simposio; 2008 AGU Fall Meeting; 2008

American Geophysical Union

We assess the quality of the transfer of elevation specific isotopic information into the rock record by comparing the stable isotopic composition of Quaternary to recent authigenic carbonates and river waters along a 3000 m elevation transect across the Andes at 33°S. Carbonate and water samples are from the Río Aconcagua (Chile) and Río Mendoza (Argentina) watersheds. Isotopic data from small tributaries of these rivers show similar elevation gradients on both sides of the range despite different initial moisture sources. The d18O of authigenic carbonates correlate well with elevation and yield an elevation gradient which is shallower than that of the rivers. These data confirm that carbonate material is indeed an accurate recorder of information about elevation, and show that in some instances, different moisture sources do not result in drastically different isotope-elevation gradients.