Using isotopic ratios of Sr, C and O, we trace calcium carbonate through surface systems across a wide region of semi-arid terrain in Arizona, southwestern USA, in order to evaluate the contribution of cations from silicate weathering to soil carbonate. We present 87Sr/86Sr ratios of soil carbonate, parent rock, dry river course silts, floodplain, playa, dust and rain samples, as well as ?18O and ?13C values of selected samples. Results show that both parent rock and dust are important sources of cations for soil carbonate in this inland setting where bedrock is dominated by silicate lithologies. Dust in southeast Arizona has higher 87Sr/86Sr ratios (0.7100?0.7123) than Phanerozoic sea water (0.7070?0.7096). These high ratios derive [...]
