The Geochemical Characteristics And Provenance Of The Surface Sediment In South China Sea

South China Sea is one of the biggest marginal seas of the West Pacific Ocean. As a copulae and interactional zone between the continent and ocean, South China Sea has special geographical location, complicated tectonic background and particularly ocean current movement, which come out the complicated sedimentary environment and diverse sediments provenances. By studying the geochemical characteristics of the trace elements, rare earth elements and lead isotope, granularity analysis together, the geochemical characteristics and provenances of the surface sediment in South China Sea were discussed with emphasis in this paper, and several deposit geochemical zones were distinguished, according to the modern sedimentary environment of the ocean. Main conclusions are summarized as follows:(1)The geochemical characteristics of the trace elements show that elements aboundence is obviously controlled by the grain size. Except strontium, the concentrations of elements in fine-grained sediment is great higher than those in coarse-grained, with a wide range of variations. Owing to different source and sedimentary environment, the element concentrations between samples are greatly different, which consequently result in distinct regional distributions of elements association, representing various supply sources respectively (terrigenous matter, biologic matter and volcanic materials). Most of trace elements have concentrations between that of continental matter and ocean matter but incline to continental matter, showing strong continental orientation. Ratios of some selected element showed on scatter plots clearly indicate the sediment samples of South China Sea are close to terrigenous matters, and its supply sourece are mainly from ambient continent.(2) The mean Σ REE of the sediment is close to Chinese loess and granites in Fujian province, far different from Pacific Ocean sediment, showing strong continental orientation too. The chondrite-normalized REE patterns exhibit that LREE are great richer than HREE in the sediments of the continental shelf, and there is remarkable minus-abnormity of europium, representing typical terrigenous components. The chondrite-normalized REE patterns of sediments in south continental shelf are different from those in North continental shelf because of having the different supply sources. Sediments in deep ocean basin evidently have richer MREE and HREE than those in other zones, and there have less minus-abnormity of europium, which reflect the biologic matter and volcanic materials greatly influenced the terrigenous matters in this area. Having MREE enrichment and evident minus-abnormity of cerium, the total REE in south coral reefs sediments is largely lower than that in other ocean zones, which indicate the dominately biologic sources of the sediment. But in total, the REE characteristics and normalized REE patterns of South China Sea sediment are very close to those of terrigenous river such as Yangtse...