川西南部地区中二叠统栖霞组岩相古地理特征

Lithofacies palaeogeography of Qixia Formation in Southwest Sichuan Basin

基于四川盆地西南部地区的野外露头、钻井、测井等资料,对该地区栖霞组的岩性及岩相古地理特征进行了分析,结果显示,四川盆地西南部地区栖霞组主要发育台内浅滩和开阔海微相,并将栖霞组划分为2个沉积旋回,分别代表栖霞期的2次海平面升降变化.其中第二沉积旋回———海平面下降阶段为栖霞期最重要的成滩期,该时期浅滩广泛发育,岩性主要为亮晶生屑灰岩,局部高地发育白云岩,经后期东吴运动改造,有望成为具有良好的储集物性特征的储集层.

The lithologic characteristics and lithofacies palaeogeography of Middle Permian Qixia Formation in southwest Sichuan Basin are analyzed according to the data from field outcrops,drilling section and well logging.It is shown that beach and open sea microfacies develop in Qixia Formation,Qixia Formation can be divided into two sedimentary cycles,and they separately were show 2 times of sea-level fluctuation in Qixia period.Meanwhile,the sea level declining phase of the second sedimentary cycle is the most important period,in this phase shallow beach developed widely,and the lithology of the shallow beach is mainly sparite bioclastic limestone and partial dolomite.The shallow beach sedimentation reformed by Dongwu movement will be favorable reservoir for further exploration.