δ13C Values of loess total carbonate: A sensitive proxy for Asian summer monsoon in arid northwestern margin of the Chinese loess plateau

We measured carbon isotope ratio of loess total carbonates (δ13Cic) from the Jingyuan loess profile in the arid northwestern portion of the Chinese Loess Plateau (CLP), in order to examine the effectiveness and sensitivity of loess total carbonate δ13Cic values as a potential paleoenvironmental indicator. The δ13Cic record in the loess profile shows large variations ranging from − 1‰ to − 7‰, during the past 70 ka. The most negative δ13Cic peaks coincide with paleosol formation; S0, L1SS1 and L1SS2, which occurred under relatively wetter climatic conditions during middle Holocene and marine δ18O stages 3. On the other hand, the least negative δ13Cic values responded to loess accumulation during relative drier phases of LGM and marine δ18O stages 4. While δ13Cic variations in the loess profile in arid area demonstrate a clear correlation with changes of total organic carbon isotope (δ13Coc) of bulk sediments which has been widely used as a proxy for the past monsoon precipitation intensity, the δ13Cic values in the loess profile are more sensitive to the changes of paleohabitat controlled by the Asian monsoon variation in the arid area. We propose that carbon isotope compositions of total carbonates in loess profile can serve as a sensitive and reliable proxy for the Asian summer monsoon in the arid northwestern Chinese Loess Plateau.

Research highlights
► We investigated carbonates carbon isotope of the loess profile in the NW Chinese Loess Plateau.
► Decreased δ13Cic is strongly correlated with the increased denser paleovegetation.
► The δ13Cic in loess profile can serve as a sensitive and reliable proxy for the ASM.