Sr-Nd isotopic geochemistry of Holocene sediments from the South Yellow Sea: Implications for provenance and monsoon variability

Elemental geochemical and Sr-Nd isotopic signatures are used to decipher terrigenous sediments provenances and transport mechanisms in the South Yellow Sea during the Holocene. 87Sr/86Sr ratios in the Chinese and Korean riverine sediments overlap each other, whereas εNd values of Korean riverine sediments are generally less radiogenic in comparison to the Changjiang and Huanghe. Moreover, εNd values of these two large rivers appear unaffected by mineral sorting and are relative stable during the Holocene. We propose a three endmembers (i.e., the Changjiang, the Huanghe, and Korean rivers) mixing model to explain sediment provenances in the Central Yellow Sea Mud (CYSM). Mixing calculations show that the Huanghe is the major sediment contributor to the CYSM before ~ 8 ka (thousand years before 1950 CE), whereas the Changjiang has become the predominant sediment source after ~ 8 ka. Holocene changes in riverine sediment supplies to the CYSM are closely related to the oceanic circulation, monsoon climate, and drainage changes. After examining several hypotheses to explain the variations in 87Sr/86Sr ratios of Core YSC-1 during the past ~ 8 kyr, we tentatively attribute that to changes in the erosion patterns of the Changjiang Basin. This in turn is associated with the asynchronous evolution of monsoon precipitation in the upper (Indian Summer Monsoon) and middle-lower Changjiang (East Asian Summer Monsoon). Therefore, our results highlight significant influences of monsoon climate on erosion patterns within the Changjiang catchment at millennial timescales.