The Origin of Siliceous Rock in Wumishan Formation, Jixian, Tianjin

Key words: 
• siliceous rock /
• storm deposit sequence /
• Wumishan formation

Abstract: SinoKeorea plate was in tensile period of Yanliao aulacogen in the Mesoproterzoic, which likely to trigger big storm. It was well developed the stromatolite and coagulum stone bioherm, and which mainly consists of dolomite interbeded with siliceous rock. Research shows that there developed storm siliceous rock in this area. Storm siliceous rock with surface of scour, siliceous gravel arranged as daisy, which was formed in storm surge, and destroyed in the late period of the diagenetic stage before they got consolidated or compacted, which resulted the siliceous fragments straight on the under layers, and formed typical storm deposit. Stromatolithic dolomite interbeded with siliceous strip was normal weather deposit. The paper concluded through the micro photo and field work that the typical storm depositional series of siliceous rock in Wumishan formation, Jixian. The scourlike structure and buninoid structure were developed in the storm siliceous rock, which were the fast and proximal sedimentary deposit. And the origin of the siliceous rock mostly could be seemed as the thermal water activities offering the SiO2. Deposit environment could be the slope of the carbonate platform.