北京西山潭柘寺地区石炭—二叠纪层序地层与聚煤作用研究

Permo-Carboniferous Sequence Stratigraphy and Coal Accumulation in Tanzhesi Temple area,Western Hills,Beijing

通过露头剖面及钻孔岩心数据,对北京西山潭柘寺地区石炭—二叠纪陆相及海陆过渡相含煤岩系进行了层序地层和聚煤作用研究。依据区域不整合面(古风化壳)、下切河道砂体底面、生物缺失带、海侵方向转换面以及岩性突变面等特征辨认出8个层序界面,据此将研究区石炭—二叠系划分为7个三级层序,分别对应于本溪组及太原组M6煤层底板以下、太原组中上部、山西组、下石盒子组、红庙岭组下段、红庙岭组上段、双泉组。根据岩相及沉积环境变化特征,可将每个三级层序进一步划分为低位体系域、海侵体系域和高位体系域。区内可采煤层(如M4)形成于下三角洲平原沉积环境,在三级层序内一般位于最大海泛面附近。

The sequence stratigraphy of Permo-Carboniferous coal measures and coal accumulation in the Tanzhesi area,Western Hills,Beijing has been studied using the borehole cores and outcrop data.The Permo-Carboniferous was dominated by coarse-grained sediments,formed in continental fluvial and paralic lagoons and delataic environments.Bounded by regional unconformity,transgression direction switching surface,the base of incised valley filled sandstones,facies reversal surface and associated palaeosols,the Permo-Carboniferous can be subdivided into 7 third-order composite sequences.Sequence I is correlated to the strata from Benxi Formation to the bottom of coal seam M6 of Taiyuan Formation,and Sequence II is equivalent to bottom of M6 to the top of the Taiyuan Formation.Sequences III,IV,V,VI and VII are correlated to the Shanxi Formation,Xiashihezi Formation,the lower part of Hongmiaoling Formation,the upper part of Hongmiaoling Formation,and Shuangquan Formation.Each of these sequences can be further subdivided into lowstand systems tract（LST）,transgression systems tract（TST） and highstand systems tract（HST） according to variation in lithofacies and sedimentary environment.The major workable coal seams,e.g.M4,which was formed in the lower deltaic plain environment around the third-order maximum flooding surface.