湘中、湘东南拗陷泥页岩层系岩相古地理特征

Lithofacies-paleogeographical characteristics of marine shale series of strata in Xiangzhong and Xiangdongnan depressions,Hunan,China

综合运用现代沉积学及地层学理论,结合湘中拗陷和湘东南拗陷构造演化背景,分析中泥盆统至上二叠统泥页岩层系沉积环境,恢复湘中、湘东南拗陷泥页岩层系岩相古地理,指示泥页岩发育的有利区带。研究结果表明,台盆相与滨海沼泽相是湘中、湘东南拗陷最有利于泥页岩沉积的相带。湘中拗陷内重要的泥页岩层系棋梓桥组、佘田桥组主要沉积于台地海盆中,分布于海侵体系域上部与高水位体系域下部,沉积中心位于涟源凹陷和邵阳凹陷中部的凹槽台地相区。湘东南拗陷内重要的泥页岩层龙潭组、大隆组则主要形成于滨海沼泽环境中,分布于海退体系域,沉积中心位于桂阳-耒阳一线。

By using the theory of modern sedimentology and stratigraphy and according to the tectonic evolution of the Xiangzhong and Xiangdongnan depressions,this paper analyzes the depositional environments of the shale or mudstone series of strata from Middle Devonian to Upper Permian,reconstructs the lithofacies and paleogeography of the Xiangzhong and Xiangdongnan depressions,and predicts the favorable regions.The study results show that the platform basin and littoral swamp are the most favorable facies for the deposition of shale and mudstone.Qiziqiao Formation and Shetianqiao Formation,the significant shale and mudstone series of strata in Xiangzhong depression,mainly deposit in the platform basin and are distributed over the upper part of transgressive system tract and the lower part of high stand system tract.The deposition center is located in the Lianyuan sag and the groove platform facies in the centre of the Shaoyang sag.The key Longtan Formation and Dalong Formation shale and mudstone series of strata in Xiangdongnan depression mainly deposit in the littoral swamp and are distributed over the regressive system tract.The deposition center is located in Guiyang-Leiyang.