威海市近海海域浅地层结构及灾害地质特征

Shallow Stratigraphic Structures and Geological Characteristics of Disaster Geology in Offshore Waters in Weihai City

通过对2 131km高分辨率浅地层剖面资料分析和研究,揭示了威海市近海海域浅地层结构特征,分析了海洋灾害地质因素类型及分布特征,并绘制了主要灾害地质因素分布图。威海市近海海域65m以浅地层共分为5层,第一层为全新世泥质楔形体,地层厚度8~15m;第二层为末次盛冰期以来的海侵层,厚度一般小于3m;第三层为MIS2期的陆相沉积层,地层厚度3~8m;第四层为MIS3期的海相沉积层,厚度3~6m;第五层未完全揭示。近海海域灾害地质因素主要包括埋藏下切谷、浅部断层、浅层气、海底沙波沙脊、浅埋起伏基岩等5种类型;埋藏下切谷主要分布在南部海域U3地层单元中;浅部断层主要分布在南部海域水深大于20m的海底堆积平原;浅层气主要分布在北部海域,东部和南部海域面积较小;海底沙波沙脊主要分布在荣成成山头外海海域;浅埋起伏基岩主要分布在基岩海岸和岛屿较近的海域。

Based on analysis and study of high resolution shallow seismic profile data in the depth of 2131km, structure characteristics in offshore shallow strata in Weihai city have been revealled, the types and distribution characteristics of marine disasters and geological factors have been analyzed, and the distribution map of main disaster geological factors has drawn. The shallow strata in the offshore area in Weihai city can be divided into 5 layers. The first layer is Holocene argillaceous wedge, and the thickness of the strata is 8-15m. The second layer is the transgression layer since the last ice age, and the thickness is generally less than 3m. The third layer is the continental sedimentary layer of MIS2 phase, and the strata thickness is 3-8m. The fourth layer is the marine sedimentary layer of MIS3 phase, and the thickness is 3-6m. The fifth layer is not fully disclosed. The geological factors of the offshore marine disaster mainly include five types, including the buried deep valley, shallow fault, shallow gas, submarine sandy ridge, shallow buried undulating bedrock, etc. The buried valley is mainly distributed in the U3 stratigraphic unit in the southern ocean. The shallow faults are mainly distributed in the southern ocean with the depths over than 20m. The shallow gas is mainly distributed in the northern sea area, and the area in the east and south is small. The bottom of the sandy ridge is mainly distributed in the sea area. The shallow buried undulating bedrock is mainly distributed in the adjacent waters of bedrock coast and island.