Sediments Sources And Transportation From The Continental Shelf Of The Northern South China Sea

The sediment provenances and transportation were discussed in this paper based upon grain-size,major element(Al2O3,TFe2O3,K2 O,Mg O,Na2 O,Ti O2,Ca O,P2O5,and Mn O),rare earth elements(REE),Sr-Nd isotopes,AMS14 C and heavy mineral for Core X2 and 47 surface sediment samples,located in continental shelf of the northern South China Sea.Results shows that coarser grain-size of surface sediment samples.The sediments belong mainly to silts,content of sand and clay are low.Two geochemistry zoning of major metals in the study area are classified according to plane distribution features of major element and clustering analysis result.Zone? located eastern continental shelf of Hainan Islands and the western of the Pearl River estuary,zone? located the Pearl River estuary and northeast area.Rare earth elements show the terrigenous clastic characteristics.Granulometric characters of the sediments could exert considerable influence on the REE concentrations.Diagenesis should have had little effect on the REE.The discrimination plots indicated that the surface sediments were a mixture of Taiwanese rivers,the Pearl River and Hainan Island rivers.Core X2 can be divided into two sedimentary strata units(unit A1 and unit A2).Compared with unit A1(240~120 cm,7.6~4.0 ka BP),sediment mean grain size in unit A2(120~0 cm,4.0~0 ka BP)became coarser and the content of major elements decreased.In addition to the abnormal value,the trends of 87Sr/86 Sr and ?Nd in core X2 were relatively stable.The sediments of core X2 were mainly derived from Hainan and Taiwan islands,Middle Holocene Pearl River delta.The sediments in unit A1 were primarily a mixture of Hainan and Taiwan islands,Middle Holocene Pearl River delta.In unit A2,the sediments were mainly from Hainan Island.The results suggested that the contribution of world-class river(i.e.,the Pearl River)to the continental shelf of the northern SCS may be overestimated,while the influence of small rivers(i.e.,Taiwan and Hainan islands)may be underestimated in the previous studies.Therefore,more attention should be paid to the contribution of small rivers to the continental shelf area in the future studies.