贵州省盘县地区龙潭组沉积特征及展布规律

Sedimentary characteristics and distribution laws of Longtan Formation in Panxian County of Guizhou Province,China

为了明确刻画贵州省盘县地区的沉积相展布规律,以上二叠统龙潭组为研究对象,通过野外露头、岩性特征、古生物特征、电性特征及沉积构造等研究要素分析了该地区龙潭组沉积相纵横向展布特征。研究结果表明:①研究区龙潭组主要发育三角洲—潮坪和潮坪—潟湖沉积体系,上段沉积相为三角洲相,下段沉积相主要为潮坪—潟湖相;②研究区晚二叠世受河流和潮汐双重作用控制,即在靠陆一侧发育河流控制的三角洲平原,中间发育河流和潮汐双重作用控制的过渡带三角洲平原,靠海一侧发育潮汐作用为主的潮控三角洲平原以及潮坪—潟湖;③龙潭早期基本为海侵期,研究区以潮坪—潟湖沉积环境为主,由于海水频繁动荡,煤层发育不稳定,可见多层煤线。龙潭晚期基本处于海退期,三角洲沉积体系在研究区广泛发育,在三角洲平原环境的泥炭沼泽局部可见厚煤层。研究结果可为下一步油气勘探开发提供一定的指导。

In this paper,the Longtan Formation was taken as the research object in order to describe the distribution laws of sedimentary facies in Panxian County of Guizhou Province clearly.The vertical and lateral distribution characteristics of the Longtan Formation sedimentary facies in the area of Panxian County were analyzed from the aspects of lithologic characteristics,paleontologic characteristics,electric characteristics and sedimentary structures.And the following research results were obtained.First,the Longtan Formation in the study area is dominated by the sedimentary systems of delta-tidal flat and tidal flat-lagoon.The sedimentary facies is delta facies in the upper member and tidal flat-lagoon facies in the lower member.Second,the Upper Permian in the study area is under the dual effect of river and tide.Therefore,river dominated delta plain is developed near the continent,transitional delta plain under the dual effect of river and tide is developed in the central area,and tide dominated delta plain and tidal flat-lagoon dominated by the tide are developed near the sea.Third,in the early Longtan period,it is basically transgression and the sedimentary environment in the study area is mainly tidal flat-lagoon.Due to the frequent fluctuation of sea water,coal seams are developed unstably and coal streaks are frequently discovered.In the late Longtan period,it is basically regression,the sedimentary system of delta is widely developed in the study area and thick coal seams are locally discovered in the peat swamp in the environment of delta plain.The research results provide some guidance for the following exploration and development.