贵州南部晚石炭世沉积环境与古地理特征

晚石炭世滇黔桂地区整体处于台盆相间格局，盆地相与台地相的特征共存。贵州南部作为台盆相带变化的典型地区，同时发育有南丹组和威宁组2种岩性组合，其中南丹组为黑色灰岩、燧石灰岩夹硅质岩，威宁组为浅灰色灰岩夹白云岩；由于缺乏地下资料，二者的界线、沉积特征及过渡关系一直不清。为此，在前人研究成果及该区3口钻井分析的基础上，采用沉积学、岩石学等方法，结合室内薄片、碳酸盐岩分析等多种手段，通过对比钻井沉积序列、生物化石及岩石组合特征，对贵州南部地区沉积相带的变化及过渡关系进行了分析和讨论。晚石炭世贵州南部贵州南部具有自碳酸盐台地边缘藻滩、碳酸盐上斜坡、中斜坡、下斜坡到台盆相的不同相带沉积特点，整体表现为一向南西方向的海退过程，且各相带存在一定的交叉与过渡。贵州南部的北部地区威宁组的出现，指示了海水的变浅和裂陷槽的封闭。

Petrological characteristics and sedimentary environment in the southern Guizhou during the Late Carboniferous

The sedimentary environment changed frequently from carbonate terraces to basin in the Late Carboniferous in the south part of Guizhou. There were two lithologic combinations at the same time, namely the Nandan Formation (black limestones and siliceous shale limestones) and the Weining Formation (light gray limestones and dolomites). However, the sedimentary environment boundary and transitional characteristics between the two formations are not clear yet. The changes and transition characteristics of sedimentary facies in the southern Guizhou were analyzed based on previous research and the analysis of three typical wells, and combined with sedimentary sequence characteristics and rock combination characteristics. It was found that in the Late Carboniferous, the southern part of Guizhou experienced a retreat from basin facies to carbonate terraces facies, and there was a certain intersection and transition between various facies. A retreat process took place in the south-west direction. The appearance of the Weining Formation in the south indicated the shallowing of seawater and the closure of a rift trough.