Provenance and environmental response of terrigenous debris in the southeastern continental shelf of Hainan Island since 7.8 kaBP

Grain-size, bulk Rare Earth Element (REE), and heavy mineral analysis of Core X2 at southeastern Hainan Island were carried out. The provenances of terrigenous clasts and their environmental responses of this study area since 7.8 kaBP were discussed. Two endmembers were identified by grain-size endmember simulation. The EM1 endmember corresponded to the fine-grained material transported by the ocean current system, while the EM2 endmember corresponded to the coarse-grained material input from nearby rivers in Hainan Island; therefore, the two endmembers represented two different transport mechanisms. Results show that since 7.8 kaBP, the provenance of terrigenous detrital of Core X2 was relatively stable, mainly from Hainan Island. After 4 kaBP, the grain size, REE, and heavy mineral characteristic parameters of Core X2 had changed significantly, which has a good correspondence to the intensification of El Nino and Southern Oscillation (ENSO). It is speculated that the increase of rainfall caused by frequent ENSO events is the main reason for the enhancement of weathering degree in the study area. Compared with the characteristics of REE, the heavy mineral assemblages of Core X2 were more significantly affected by weathering and denudation in the source area. Therefore, study on heavy mineral index is suggested in the future study of environmental evolution.