HEAVY MINERAL DISTRIBUTION AND MAGNETIC CHARACTERISTICS OF SURFACE SEDIMENTS IN THE NORTH BRANCH OF THE CHANGJIANG RIVER

Based on data from the surface sediments obtained from the north branch of the Changjiang River, this paper deals with the distribution of heavy minerals, the spatial variations of sediment magnetic properties and their controlling factors. Results indicate that hornblende and epidote dominate in heavy minerals in the research area, followed by mica and magnetite, but mineral assemblages vary in different sedimentary dynamic zones. The mica-stable mineral assemblage mainly occurs in sandspits and tidal sands,where, under strong hydrodynamic conditions, coarse sediments prevail and magnetic parameters, such as Xarm、X_fd%、Xarm/X_l and Xarm/SIRM are relatively low. The assemblage of hornblende-magnetite-carbonate is mainly distributed in river channels and tidal inlets, where hydrodynamic condition is relatively low and fine sediments, such as clayey silt, dominate, and as the result, magnetic parameters of Xarm、X_fd%、Xarm/X_l and Xarm/SIRM are quite high. Data suggest that the sediments in the north branch of the Changjiang River are mainly from the Changjiang River drainage. The distribution of heavy minerals and magnetic parameters are controlled by hydrodynamics, sediment types, source rocks and sediment transportation.