A COMPARATIVE STUDY OF DRIP WATER AND MODERN CALCITE CA ISOTOPE RATIOS WITH RAINFALL, C ISOTOPE RATIOS, AND TRACE ELEMENT DATA FROM THREE US CAVE SYSTEMS
We present a comparative study of δ44Ca data and coeval measurements of δ13C and trace element ratios, established proxies for water infiltration, from cave drip waters, farmed calcite, and host rocks from three different cave systems - White Moon Cave (WMC) in coastal California, Lake Shasta Caverns (LSC) in northern California, and Blue Springs Cave (BSC) in east-central Tennessee. These cave systems are characterized by different hydroclimate, geology, flow path geometry, and seasonal infiltration characteristics. To assess the relationship between Ca isotope evolution and effective rainfall we also compare cave system δ44Ca data with local rainfall rates and supplement these comparisons with drip rate information when possible.
The comparison of WMC, LSC, and BSC δ44Ca, δ13C, and trace element data from sites with different flow path geometry and from caves in different geologic and climate settings allows independent assessment of these key factors. This work, and the direct comparison between δ44Ca measurements and measured local rainfall rates in particular, aids in the refinement of speleothem δ44Ca as a new, (semi) quantitative proxy for paleorainfall.