CHARACTERISTICS AND INFLUENCE FACTORS OF VALUABLE HEAVY MINERALS IN SURFACE SEDIMENTS OF THE EASTERN BOHAI SEA AND THE NORTHEN YELLOW SEA

In this paper, we synthetically analyzed the heavy sands picked out from the 234 surface sediment samples taken from the Eastern Bohai Sea and the Northen Yellow Sea. It seems that the heavy minerals of monazite, garnet, ilmenite and zircon are economically valuable and thus their grades are measured and calculated. High grade areas are located in the northern Bohai Strait, the southeast Liaodong Peninsula and the southern North Yellow Sea. Grain size analysis indicates that the sediments are high in sand content with better sorting. It is inferred that the Yalu River, southeast coast of the Liaodong Peninsula, Changshan Archipelago, Laotieshan Channel and the relict deposits before the Holocene are provenances of the heavy minerals. The enrichment of valuable heavy sands depends upon hydrodynamic conditions, such as, a) coastal current, which effectively transported the sediments from proximal rivers; b) strong tidal current from the north Yellow Sea, which worked for the enrichment of heavy placer minerals; c) the Yellow Sea warm current, which effectively constrained the diffusion of fine grained material from the Yellow River and protected the enrichment region of valuable heavy minerals.