Distribution, Provenance And Control Factors Analysis Of Marine Sand Resources In Bohai Sea

Marine sand is fine sand, medium sand, coarse sand and gravel sand located incoastal and continental shelf waters, in the form of underwater sand bar, tidal sandridges or tidal delta. Marine sand is very important marine resources. With the rapiddevelopment of the coastal economy, especially the constant expansion of the coastalindustrial zone construction, the demand of construction sand and filler increasinglyrise. The research of marine sand has become a basic work for the rationaldevelopment and utilization of marine sand resources.Bohai sea is an important area of marine sand resources.Based on the particle sizeanalysis of4941surface sediment samples in Bohai Sea, funded by the908Specialinvestigation, seven marine sand resources areas are determined, including thenorthern part of Bohai Strait, Liaodong Shoal, east coast of Liaodong Bay,Xingcheng-suizhong inshore, Qinhuangdao inshore, Caofeidian, Laizhou shallows.Their total area is about12800km². The sediment characteristics and distribution ofheavy minerals in the marine sand resources areas are analyzed. The zircon content ofthe northern part of Bohai Strait marine sand resources area is high, and the sedimenttype is gravelly sand or sandy gravel. The hornblende and epidote content of eastcoast of Liaodong Bay marine sand resources area is high, and the sediment type iscoarse sand. The titanium iron ore and magnetite content of Xingcheng-suizhonginshore marine sand resource area is high, and the sediment type is coarse sand. Thegarnet content of Qinhuangdao inshore marine sand resources area and Caofeidianmarine sand resources area is high, and the sediment type is mostly fine sand. Thesediment type of Laizhou shoal marine sand resources area is mostly coarse sand andmedium sand. The resources of east coast of Liaodong Bay marine sand resourcesarea amount to90.0×10⁸m³, and the resources of Xingcheng-suizhong inshore marinesand resources area amount to337.0×10⁸m³.Compared to the results of previous studies, the provenance of every marine sand resources area is analyzed. The northern part of Bohai Strait marine sand resourcesarea is formed by the Laotieshan waterway tidal current of long-term erosion.Thematerial of Liaodong shoal marine sand resources area sources from the accumulationof Laotieshan watercourse erosion. Other marine sand resources areas mainly derivefrom the coastal rivers. The Yellow River has no significant contribution for theformation of the Bohai marine sand resources area.This paper collects the data of8flow measurement stations in the marine sandresources areas. Using numerical simulation method to study the dynamics relationsof the development of sand ridges and sand seats in Bohai sea, then comes to theconclusion that M₂tidal current is the main controlling factor and other tidal currenthas no significant effect. With adequate provenance, the area can develop tidal sandridges if M₂tidal current elliptical semimajor is50cm/s to75cm/s, and the absolutevalue of ellipsoid rate is less than0.4. The direction of sand ridges and the direction ofelliptical semimajor is basically the same; the area can develop tidal sand seats if M₂tidal current elliptical semimajor is40cm/s to50cm/s, and the absolute value ofellipsoid rate is between0.4to0.6.The area cannot develop tidal sand ridges or sandseats if M₂tidal current elliptical semimajor is too large or too small.Using the main rivers’ runoff and sediment discharge records in Bohai, tidalcurrent of numerical simulation data, historical remote sensing image data, this paperanalyzes the causes of marine sand resources. The results show that the factors thatcontrol the distribution of the Bohai marine sand resources are sand sources and tidalcurrent. Human factors have a greater impact on the Caofeidian marine sand resourcesarea and Laizhou shoal marine sand resources area. Compared to mud area, themarine sand resources areas have larger tidal current. The marine sand resources areasare shrinking because the material sources are reducing.