Stratigraphy and Moisture Changes revealed from Iranian Loess- Paleosol in the Western Arid Central Asia since the Last Interglacial

Climatically controlled by Westerlies, the climate change in the Arid Central Asia (ACA) has significant‘westerlies-dominated climatic regime’ characteristics during Holocene. However, the change of moistureduring the last glacial-interglacial cycle in the ‘winter rainfall type’ western part of ACA is still unclear. Inthis study we chose a loess-paleosol sequence named Toshan۱۹ section in northeastern Iran, pIRIR datingdata have been applied to control the chronology, the proxies including grain-size, chromaticity, TOC andorganic carbon isotopic ratio (δ۱۳C) have been measured to study the stratigraphy and moisture changes.We found that: ۱) the top age of this profile is about ۲.۷ ka, and the bottom age is older than ۱۳۰ ka, whichindicates that this loess-paleosol profile could be used to reveal stratigraphy and moisture changes in thelast glacial-interglacial cycle. ۲) During the last interglacial period and Holocene, the higher redness andTOC values indicate warmer and wetter climate condition, and with more vegetation and higher intensityof pedogenesis when comparing with that in the glacial period. ۳) Combining with the surface soil δ۱۳Cresult, we quantitatively reconstructed the Mean Annual Precipitation (MAP) since the Last Interglacial,the results show that highest MAP happen in the MIS۵a instead of MIS۵e, which is totally different withthat in the Xinjiang loess and Chinese Loess Plateau loess records.