GEOLOGICAL CHARACTERISTICS AND ORIGIN OF MARINE SANDSIN THE NORTHEAST SEA OFF HAINAN ISLAND

Holocene marine sands or marine aggregates are widely distributed in the water off the northeastern Hainan Island. It may reach hundreds of square kilometers in area, and more than 10 meters in thickness. Based on the survey of water depth, sediment particle size and other geological properties, the regional distribution pattern, scale and size, thickness and sedimentary environments are studied, and the quality and economic significances preliminary evaluated in this paper. High quality marine sannds are mainly distributed in the tidal ridge area of the East mouth of the Qiongzhou Strait, where the deposits are as thick as 20 meters and consist of subrounded grains. The content of sand is higher than 80%. The Sea sands are believed to be the joint product of topography and tidal current or the Holocene tidal depositional system on continental shelf. The nearshore areas are mainly supplied by the sediments from the inner Qiongzhou Strait and the West Guangdong Province, and the material supply from Hainan Island are relatively small.