Clumped and stable isotopes of land snail shells on the Chinese Loess Plateau and their climatic implications

We report stable (delta C-13(shell), delta O-18(shell)) and clumped isotope (Delta(47)) compositions of modern and last glacial fossil snail shell carbonates from the Luochuan and Weinan sections on the central and southern Chinese Loess Plateau (CLP). Our study reveals that the average Delta(47) temperature (T-47) of modern snails is consistent with monitored temperatures during the snail growing season at the studied locations and is similar to 10 degrees C higher than that of fossil snails from glacial time. Moreover, the average delta C-13(shell) of modern snails is more depleted than that of fossils. We argue that the delta C-13(shell) cannot record changes in plant communities (i.e., the C3/C4 ratio) on the CLP and may mainly indicate arid conditions with depleted values reflecting reduced aridity. Additionally, the reconstructed snail body water delta O-18 (delta O-18(water)) of modern snails is more enriched than delta O-18 in modern growing season precipitation and delta O-18(water) of fossils. This contrast may be related to the high degree of evaporative enrichment of environmental water O-18 in the body/ingested by modern snails under warm conditions. Therefore, we suggest that using delta O-18(shell) to directly reconstruct the oxygen isotopes of precipitation is difficult and that higher delta O-18(shell) and delta O-18(water) values probably indicate higher environmental temperature/stronger evaporative enrichment on glacial-interglacial timescales on the CLP