内蒙古林西地区二叠系林西组泥质岩石动力变质

内蒙古中部林西地区发育有北东向构造带，该构造带靠近西拉木伦河缝合带，使该区林西组地层部分经受了动力变质作用改造，构造带以外林西组地层未遭受动力变质。此动力变质带内劈理发育，变质的泥岩和泥质粉砂岩构造置换现象强烈。动力变质带内部变形变质强度极不均匀，其间有石英细脉贯入，有的部位变形变质程度高，形成二云母构造片岩，出现了黑云母+ 白云母+ 绿泥石+ 斜长石+ 石英等变质矿物组合，其中黑云母化学组成为Fe2 + ( 1. 38% ～ 2. 63%) ，Mg2 + ( 1. 93% ～ 2. 47%) 、K + ( 0. 96% ～ 1. 38%) ; 白云母为Si4 + ( 6. 13% ～ 6. 78%) 、Al［Ⅳ］ ( 1. 22% ～ 1. 87%) 、K + ( 0. 93% ～ 1. 46%) 。根据二云母地质温度计估算的动力变质作用PT 条件为0. 3 GPa，480℃，有的部位只有脆性变形，没有新生变质矿物出现，只有变形没有变质。其动力变质作用研究为松辽盆地及外围上古生界油气资源评价提供了地质依据。

Dynamic metamorphism of argillaceous rocks of Permian Linxi Formation in Linxi region, Inner Mongolia

Linxi area in the middle of Inner Mongolia developed north-east trend tectonic belt near the Siramulen River suture,leading to dynamic metamorphism of partial Linxi Formation statra,and outside the belt was not subjected to dynamic metamorphism.In the dynamic metamorphic belt developed cleavage,and in the metamorphic mudstone and in the muddy siltstone occurred intense tectonic replacement.Intensity of deformation and metamorphism in the metamorphic belt is uneven with quartz veinlets penetrated.Some parts with strong deformation and metamorphism formed two-mica schist,and its metamorphic mineral assemblages is composed of Bt＋Ms＋Chl＋Pl＋Q,in which biotite is chemically composed of Fe2＋（1.38%~2.63%）,Mg2＋（1.93%~2.47%） and K＋（0.96%~1.38%）;muscovite consists of Si4＋（6.13%~6.78%）,AlⅣ]（1.22%~1.87%） and K＋（0.93%~1.46%）.According to the estimation of the two-mica geothermometer,the PT condition of dynamic metamorphism are 0.3 GPa and 480 ℃.Some parts are only in brittle deformation,with no new metamorphic minerals occurced;and are only in deformation withnot metamorphism.The study of dynamic metamorphism provided the geological basis for the assessment of the Upper Paleozoic oil and gas resources in the Songliao Basin and its peripheral.