黔桂地区石炭系层序地层格架及海平面变化

从石炭系到下二叠统，构成一个二级层序，其底面为紫云运动主幕不整合面及其相关面，顶界面为黔桂运动不整合面及其相关面，包含6个三级层序。研究区范围内，从连陆台地到孤立台地乃至台沟背景，沉积特征明显不同，如在连陆台地上发育煤系地层并且发育较多的白云岩地层，而在孤立台地上则以大套碳酸盐岩地层为特征，台沟背景中以暗色细粒沉积为主包括台盆相和台棚相沉积。因此，三级沉积层序的相序特征形成有规律的空间变化，虽然在不同的地点三级层序的形成时限和相序组构存在差异，但它们所代表的相对海平面变化过程基本上是同步的。在前人大量的古生物学研究成果的基础上，追索各三级沉积层序界面的空间展布特征，以地层记录中的两种相变面和两种穿时性为基本要素，可以建立黔桂地区石炭系(含下二叠统)的地层层序格架。

Carboniferous Sequence Framework in Guizhou and Guangxi,Southern China

Carboniferous in Guizhou and Guangxi might be divided into four series, namely Yanguan, Datang, Weining and Maping. The Maping formation, traditionally regarded as the upper Carboniferous lithostratigraphic unit, is now considered to be an intersystem unit from Carboniferous to Permian. Hence, the top part of Carboniferous and the bottom part of Permian (Chuanshan Series) in Guizhou and Guangxi constitute a third order sedimentary sequence. In the study area, Carboniferous System and Permian Chuanshan Series form a second order tectonic sequence that contains 6 third order sequences. The bottom of the second order sequence is a nonconformity surface resulting from the principal episode of Ziyun epeirogeny, and the top surface is also a nonconformity surface caused by the principal episode of Qiangui epeirogeny. Strata of Carboniferous and Chuanshan Series have obviously different sedimentary features. Coal measures and relatively abundant dolomitic strata are developed in the connecting platform, strata of the isolated platform are marked by carbonate rock, strata of the inter platform ditch are mainly composed of dark fine grained sediments, and therefore the third order sequences with different peculiarities of facies succession are formed in different areas. Although time spans and peculiarities of various third order sequences are somewhat different, the processes of relative sea level change represented by these third order sequences remain synchronous on the whole. On the basis of biostratigraphy, the surfaces of third order sequences could be correlated and traced in space, the framework of sequence stratigraphy from Carboniferous to Chuanshan Series of Permian in Guizhou and Guangxi could be constructed in term of two types of facies changing surfaces as well as two kinds of diachronism in stratigraphic records.