蓟县雾迷山组碳酸盐岩原地型风暴沉积特征及成因探讨  

The Features and Geneticdiscussion of Carbonate Autochthonous Tempestite in Wumishan Formation in the Jixian

作　　者：安桐林 

机构地区：[1]天津市地质调查研究所

出　　处：《沉积学报》1993年第4期30-36,共7页Acta Sedimentologica Sinica

摘　　要：蓟县地区雾迷山组碳酸盐岩地层中发育原地型风暴沉积,它具有A、B、C和D四个沉积单元,即下部单元A为丘状角砾岩,中部单元B为波纹状层理,上部单元C为水平层理,顶部单元D为厚层一块层状层理,运用现代气象学和海洋水文学的研究成果,文章对该区原地型风暴沉积的成因作了初步探讨,认为在风暴作用下,形成海水高速涡漩,受风暴控制的碳酸盐台地或浅海沉积盆地底部沉积物被剪切、打碎而形成角砾,风暴衰减后,几乎在原地沉积下来,形成了具有独特韵律的沉积构造。It grows a group of the autochthonous storm deposits in the Wumishan formation of the middle - late Proterozoic in the Jixian area. The complete depositional sequence character is: the bottom unit is the silex striped fine - powdery graded dolomitite. The lower unit A has two types, one is the autochthonous storm-fringe deposits, it's the silex striped dolomitite and fine graded dolomitite, there is a hummocky stirring bedding in the strate, the other is the autochthonous storm-center deposits, it's hummpcky breccia, the tabular breccias of silex and dolomitite show vertical fan, radiating, sheaf, radiator arrangement in the section and triangle trellis arrangement on the surface. The middle unit B is the white and black streaking powery -fine graded dolomitite with corrugated bedding. The upper unit C is the silex striped asphaltic fine graded dolorm-lite with horizontal bedding. The top unit D is the silex striped stromatolites dolomitite with thick -massive bedding. The uncomplete depositional sequence is: the unit B or C often absent, only it's the A that is a mark to identify the autochthonous storm deposits. During the deposition of the Wumishan formation of the middle -late Proterozoic, the platform of the Jixian area was in Pacific Ocean, the palaeolatitude was 1°-10°N, the depth of seawater was less in the basin. The sedimentary environment was shallow sea. It was the same as the area of 5°-20°N latitude of the modern storm movement. There must were storm moving here during the Wumishan formation. A strong vortices storm whirled the seawater highly during the storm event. The strom wave base was deepened to get to 200m depth, the seabed geted huge shearing stress U which can be resloved into horizontal U1 and vertical U2. When weak storm, U2 was a little force which couldn't cut out anything on the seabed, U1 pulled the sediments of seabed to go to vortes point, hummocky stirring bedding was shapeed. This is the autochthonous storm -fringe deposits. When stron storm, U1 pulled and U

关 键 词：碳酸盐岩 风暴沉积 成因 雾迷山组 

分 类 号：P512.21[天文地球—地质学]