Speleothems (secondary calcium carbonate formations) offer significant potential for recording environmental processes above caves, an area increasingly referred to as the Critical Zone. Speleothems grow for hundreds to millions of years, with absolute chronology from U-Th and U-Pb chronometers. The solution properties of rainwater infiltrating the soil and underlying caves respond to environmental controls. These environmental signals can be preserved within speleothem carbonates. Recent efforts to calibrate, model and interpret this complex geochemistry has progressed along multiple paths. Here we bring together recent examples, including: i) calibrating and using Li isotopes for reconstructing weathering intensity [1,2]; ii) the use of Ca isotopes for reconstructing changes in rainfall amount ; iii) the combined use of d13C, 14C and d44Ca to demonstrate changes in soil respiration . Combining these proxies provides the potential of regional-scale input into climate, weathering and the chemical cycling of elements, on timescales from thousands to millions of years.
 C.C. Day et al. Lithium isotopes and partition coefficients in inorganic carbonates: proxy calibration for weathering reconstruction. GCA.  P.A.E. Pogge von Strandmann et al. 2017. Lithium isotopes in speleothems: Temperature-controlled variation in silicate weathering during glacial cycles. EPSL. 469, 64–74.  R.A. Owen et al. 2016. Calcium isotopes in caves as a proxy for aridity: Modern calibration and application to the 8.2 kyr event. EPSL, 443, 129–138.  F.A. Lechleitner et al. (in review). Stalagmite carbon isotopes suggest deglacial increase in soil respiration in Western Europe driven by temperature change. Climate of the Past.
Christopher Day1, Philip Pogge von Strandmann2, Franziska Lechleitner3, Heather Stoll4
1University of Oxford, United Kingdom; 2Johannes Gutenberg University, Mainz, Germany; 3University of Bern, Switzerland; 4Geological Institute, ETH Zurich, Switzerland