Distribution and provenance of detrital minerals in surface sediments of the northeastern East China Sea

In order to understand the source of surface sediments and the characteristics of the depositional environment on the East China Sea Shelf, 180 surface sediment samples from the southwest waters of Jeju Island were analyzed in terms of sediment types and detrital mineral compositions by means of grain size and mineralogy. The relationship between the distribution characteristics of minerals and the depositional environment was discussed. Based on the sedimentary dynamics method, the influence of the transport mode, material source and circulation system of the surface sediments on its distribution was clarified. Thirty-four heavy minerals were identified, mainly common amphibole, epidote, and metallic minerals. Olivine and metamorphic rock minerals are the landmark minerals distinguished from inland shelf deposits. Thirteen light minerals were identified, which are characterized by commonly developed glauconite. According to the distribution characteristics of clastic mineral assemblage, the study area could be divided into two mineral assemblages named as Zone Ⅰ and Zone Ⅱ, correspondingly. Zone Ⅰ occupied in the central modern sedimentary zone characteristic of ordinary amphibole, epidote, authigenic pyrite, metallic minerals, and sheet minerals, showing colors of modern terrigenous sediments from mainly the Yellow River, biological, and authigenic sediments. Zone Ⅱ covered the peripheral residual sedimentary zone characteristic of weak reductive environment with slow sedimentation rate. Zone Ⅱ could be divided into two subzones. Subzone Ⅱ-1 features ordinary amphibole, epidote, metallic minerals, garnet, and olivine, indicating the origin of the ancient Yangtze River on the basement of foreset sediments with the influence of Zone Ⅰ, receiving a small amount of modern terrigenous suspended or resuspended sediments with own regional uniqueness. Subzone Ⅱ-2 contains epidote, ordinary hornblende, metal minerals, and garnet etc, reflecting residual sediments of the ancient Yangtze River. Under the action of the central cold vortex, few modern materials could be added. Meanwhile, local organic substances in local environment that are mutually exchanged with zone Ⅰ cannot be excluded from the area. The research content of this paper provides a new reference for further studies on sedimentology, mineralogy and environmental evolution on the East China Sea Shelf.