贵州平塘地区上二叠统长兴组沉积相与层序地层特征
Sedimentary facies and sequence stratigraphy of Upper Permian Changxing Formation in Pingtang, Guizhou Province
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摘要: 提要：本文应用沉积学和层序地层学的基本原理和方法，采取野外实测与室内微观研究结合，利用区域钻井资料对比层序地层，对贵州平塘地区中上二叠统长兴组的沉积相特征、层序地层特征以及岩相古地理平面展布进行了研究和总结。结果表明，贵州平塘地区上二叠统长兴组发育开阔台地、台地边缘浅滩以及台盆3种沉积环境。长兴组可划分为2个Ⅲ级层序PSQ1和PSQ2，且均由海侵体系域(TST)与高水位体系域(HST)两部分组成，且皆为TST >HST。对比邻区沉积相和层序地层特征，说明纵向上长兴组的沉积环境是由开阔台地、台地边缘浅滩沉积变为深水台盆沉积；横向上自西向东从安顺到甘寨一带在上二叠统层序PSQ2时期，构成了由浅水碳酸盐台地到深水台盆沉积的廊带。且黔南坳陷在晚二叠世，海水总体为由南向北迁徙海侵。Abstract: Abstract：Using the basic principles and methods of sedimentology and sequence stratigraphy, combining field measurements with indoor microscopic study, and applying drilling data to correlating data of regional sequence stratigraphy, the authors studied and summarized sedimentary facies characteristics, sequence stratigraphy and lithofacies paleogeography distribution of Upper Permian Changxing Formation in Pingtang, Guizhou Province.. The results demonstrate that three kinds of sedimentary environments exist in Upper Permian Changxing Formation, i.e., open platform, shoal of platform margin and inter-platform basins. The Changxing Formation of the study area can be divided into two third-order sequences of PSQ1 and PSQ2, and both are composed of the transgressive systems tract (TST) and the highstand systems tract (HST), with the thickness of TST larger than that of HST. A comparison with the sedimentary facies and sequence stratigraphy characteristics of adjacent areas indicates that the sedimentary environments of Changxing Formation must have been open platform, shoal of platform margin and deep inter-platform basins in vertical direction. In the eastward transverse direction, there formed the sedimentary belt of shallow-water carbonate platform and deep basin sediments in the area of Anshun to Ganzhai during the PSQ2 period of late Permian. During late Permian, sea began the transgression from south to north.
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