In-situ cosmogenic ³⁶Cl denudation rates of carbonates in Guizhou karst area

摘要

This study quantifies surface denudation of carbonate rocks by the first application of in-situ cosmogenic Cl in China. Concentrations of natural Cl and in-situ cosmogenic Cl in bare carbonates from Guizhou karst areas were measured with isotope dilution by accelerator mass spectrometer. The Cl concentration varied from 16 to 206 ppm. The Cl concentrations were in range of (0.8–2.4)×106 atom g−1, resulting in total denudation rates of 20–50 mm ka−1 that averaged over a 104–105 a timescale. The Cl-denudation rates showed roughly a negative correlation with the local mean temperature. This preliminary observation may suggest the variations of proportions of chemical weathering and physical erosion in denudation process, depending upon local climatic conditions.