石炭纪—早二叠世滇黔桂盆地北缘深水区的地层序列及沉积演化

Carboniferous-Early Permian deep-water succession in northern margin of the Dian-Qian-Gui Basin and its sedimentary evolution

通过分析石炭纪—早二叠世滇黔桂盆地北缘深水区的地层序列和沉积特征,探讨沉积演化过程及其控制因素。研究区深水地层序列包括下述的9个岩石地层单元:鹿寨组(C_1lz)、巴平组(C_1bp)、下如牙组(C_1xr)、上如牙组(C_1sr)、王佑组(C_1w)、睦化组(C_1m)、打屋坝组(C_1dw)、南丹组(C_1-P_1nd)和船埠头组(C_1c),并且可以识别出4种主要的深水沉积相:台间盆地相、斜坡相、深水陆棚相和台前斜坡相,以砂岩、碳质页岩、硅质泥岩、硅质岩、钙屑碎屑岩、泥晶灰岩和白云质灰岩为主要特征,与桂西南深水盆地的差别显著。依据地层序列和沉积组合的时空分布特征,可以将石炭纪—早二叠世滇黔桂盆地北缘深水区的沉积演化划分为3个阶段:1)裂谷作用强烈期(早石炭亚纪汤耙沟期早期);2)裂谷作用减弱期(早石炭亚纪汤耙沟期中期—德坞期);3)裂谷作用稳定期(晚石炭亚纪—早二叠世)。

Analyses of stratigraphic succession and sedimentary characteristics of the Carboniferous-Early Permian deep-water facies in northern margin of the Dian-Qian-Gui Basin enable us to reconstruct the sedimentary history and its control factors.The Carboniferous-Lower Permian,which includes totally nine lithostratigraphic units,the Luzhai Fm.（C1lz）,Baping Fm.（C1bp）,Xiaruya Fm.（C1xr）,Shangruya Fm.（C1sr）,Wangyou Fm.（C1w）,Muhua Fm.（C1m）,Dawuba Fm.（C1dw）,Nandan Fm.（C1—P1nd）and Chuanbutou Fm.（C1c）,is characterized by sandstone,carbonaceous shale,siliceous mudstone,siliceous rock,debris flow deposits,mudstone and dolomitic limestone,which are quite distinct from those of the deep-water basin in southwestern Guangxi.Based on the detailed observations on the lithofacies,microfacies characteristics,sedimentary structure and fossil assemblage of key sections,four sedimentary facies can be recognized,including the intra-platform facies,slope facies,deep-water shelf facies and platform foreslope facies.The stratigraphic architectures and characters suggest that sedimentary evolution of northern margin of the Dian-Qian-Gui Basin could be divided into three stages：period of intense rifting（Early Tangbaguan）,period of reduced rifting（Middle Tangbaguan-Dewuan）and period of stable rifting（Late Carboniferous-Early Permian）.