黔中早二叠世茅口晚期断裂陆缘层序地层分析

Analysis of Sequence Stratigraphy in the Fractured Continental Margin,Late Maok ouian, Early Permian,Central Guizhou Province

黔中早二叠世晚期发育变异多姿的硅质岩－碳酸盐岩和火山岩，笔者通过大地构造学、火山岩岩石学和岩石地球化学、层序地层学的综合分析认为，与一般的被动大陆边缘不同，该区这种断裂大陆边缘的层序地层特征主要依据纵向上反映海平面变化的岩性突变来识别，而岩性突变又是构造变动的反映。据此，将该区茅口组二段划分为一个准层序组和两个准层序，每个准层序以突变最大海泛面为基础，包含了凝缩层和加积高位体系域；横向上解释为破裂碳酸盐台地型层序地层格架，即把构造作用与层序地层格架的形成以及沉积体系的分异统一起来。

Silliceous rocks,carbonate rocks and volcanic rocks are widespread in the upper Maokou formation of Early Permian in the centra part of Guizhou Province.Based on the synthetic analysis of tectonics,petrology, geochemistry and sequence stratigraphy,the tectonic setting is supposed to be fault controloled continental margin.Under the condition of this tectonic setting,the characteristics of sequence stratigraphy is different from those of passive continental margins and foreland basins aswell as from the other tectonic unit.The sequencoe bounding surface of the fault control ed continental margin can be distinguished by the sudden lithologic cnange,which implies tectonic changes.The tiferal differentiation of the depositional system tract in each sequence has a relationship with the strength of upper crust fault caused by deep magmatism.Based on the basic characteristics of tectonics and sedimentology,the second member of the Maokou formation could be clasisfied into one parasequence group with two parasequences,and each of them takes the amfs as its base,including condensed section and progradational highstand system tract;it is explained as a sequence stratigraphic architecture of the broken carbonate platform which can be further divided into remnant platform,progradational isolated platform,platform trough of fault trough and ramp facies, etc.The example of the sepuence stratigraphic analysis on the fault controlled continental margin is raised by combining tectonism,of sedimentary sysyten together. the formation of sequence stratigraphic architecture and the variation.