The Potential evaluation of marine sand resources in the northern sea areas of Hainan Island

The shallow sea in the north of Hainan Island is rich in marine sand resources, which are mainly composed of sand and gravel deposits. The marine sand resources are concentrated on the tidal ridge area of the east mouth of Qiongzhou Strait, estuary delta and submarine coastal slope. Through the investigation of the bedform, strata and sediments of the seafloor, the distribution and the scale of marine sand resources in two regions were discussed separately together with the marine sand geological features, and the marine sand resource volumes were also estimated. On the basis of the different sediment environments, marine sand resources potential has been discussed systematically. The marine sand in the study area is widely distributed, but the characteristics and scale of the east region and the west region are quite different. The marine sand in the west region is mainly sandy gravel and muddy sand with a thickness of 5 to 10 meters, whereas the marine sand in the east region is dominated by sand, gravel sand and gravel with a thickness of 10 to 50 meters, suggesting a larger scale than the west region. There are totally 9 resource potential areas with a resource volume of 9.14 billion m³, and the rest of the area is a prospective area with a resource volume of 7.15 billion m³. According to such factors as topography, hydrodynamic and sedimentary environment, the marine sand sediment system can be divided into tidal sand ridge accumulation system, estuary underwater Delta accumulation system, submarine coastal slope accumulation system and erosion residue system. Among them, the tidal sand ridge accumulation system located in the shallow water area of the eastern part of the Qiongzhou Strait has a continuous distribution area of 328 km², an average thickness of more than 25 meters, and a resource volume of 8.39 billion m³, suggesting huge resource potential.