Stratigraphic Characteristics and Dating Basis of Tuanshi Louqian Formation in Yongan City,Fujian Province
A set of metamorphic pyroclastic rocks has been found in the Tuanshi area in the south of Yongan.The deformation of the rocks is weak and the metamorphism is shallow.The original rock structure and structure are mostly preserved.The main rock type is metamorphic crystalline tuff.Volcanic eruption is empty phase,showing strong volcanic activity characteristics.The profile comparison between the Louqian Formation of the study area and the Changting Zhangdi Louqian Formation shows that the stratification in the area is only equivalent to the lower part of the Zhangdi Louqian Formation.The LA-ICP-MS zircon U-Pb isotope dating sample shows that the crystal shape of the zircon CL image is well developed and the rhythm zone is clear.The Th/U ratio is high,ranging from 0.58 to 4.85,which is characteristic of magmatic zircons.The U-Pb age of the zircon is(754.8±3.3)Ma,which represents the diagenetic age of the metamorphic volcanic rocks,indicating that the geological age of the Louqian formation is Nanhua Period.
dataing basisstratigraphic characteristicsTuanshi Louqian FormationYongan city of Fujian
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