Mineral provinces and matter source in surface sediments near the Zhongsha Islands in the South China Sea

Characteristics and distribution patterns of clastic minerals(0.063~0.125 mm in grain diameter) in bottom sediments are a significant indicat or for the identification of the origin of sediment.114 surface sediment samples,which were collected from the area near the Zhongsha Islands in the South China Sea, were analysed to identify the mineral suites and the their distributions in the study area.The area can be divided into three mineral provinces.Province Ⅰ of biogenic minerals:Amineral assemblage is very simple and is made up of the biogenic detritus minerals,except that the biogenic minerals are mainly originated from the Zhongsha Atoll,a very small quantity of volcano genic minerals and terrigeno us minerals can be transported into this province by means of wind and suspension.Province Ⅱ of volcanogenic mineral: Light minerals in this province mainly include brown volcanic glass,volcanic scoria and color less volcanic glass;the mineral assemblage in this province is made up of brown volcanic glass and volcanic scoria;the content of weathering detritus and terrigeno us minerals is very low;the volcanic scoria in this province takes on distribution pattern from "point source"diffusion;the material source of this province is relatively complicated;the detrital minerals are mainly derived from local basaltic seamounts and small-scale volcanoes that are probably erupting,with some influences from the island-arcvolcanic region around the South China Sea,and island-arc-volcanic regions around this study area have a little influence on modern sedimentation in the study area.Mixed mineral province Ⅲ,in which the material source includes biogenic minerals,volcano genic minerals and terrigenous minerals.The last province can be subdivided into a mixed mineral sub-province Ⅲ-1.of the northeastern part of the study area,the mineral assemblage mainly includes biogenic detritus minerals,brown volcanic glass,quartz and feldspar.in which terrigeno us minerals are mainly derived from China's Mainland and do not exceed 17°N;and a mixed mineral sub-province Ⅲ-2 of the southeastern part of the study area,the mineral assemblage is biogenic detritus minerals,brown volcanic glass, quartz and weathered detritus,terrigenous minerals in this area are derived from Kalimantan and Indo-China Peninsula and might be further transported into the deep-sea basin through submarine canyons.