【作者】 姚尧；

【导师】 王根厚；

【作者基本信息】 中国地质大学(北京) ， 地质工程， 2012， 硕士

【摘要】 研究区位于西藏自治区北部，地处青藏高原羌塘盆地腹地，为北昌都板块与羌南保山板块两个板块的结合部位。本文研究的构造片岩分布较为广泛，分布于整个图幅中部和西部大部分地区，主要是石炭-二叠系。构造片岩主要经历了三期变形、两期变质作用，区域性面理为S2。沿面理S1及S2分布有绿泥石绢云母等变质矿物，沿面理S3分布有绢云母铁泥质。第一期韧性条件下的剪切变形，形成了剪切型褶劈理S1，为透入性的区域面理，露头中其与原始层理S0近平行，其间分泌有同构造的石英细脉，并发生了强烈的柔流褶皱现象。第二期为水平收缩变形，发育有区域性的透入面理S2，为轴面型褶劈理。第三期变形在露头尺度上多表现为面理S1、S2形成的挠曲状或膝状褶皱，其褶皱轴F3与F2相互垂直。随着构造片岩的变形变质作用，石英脉在宏观上发育石英碎斑系、同构造石英脉、柔流褶皱、尖棱褶皱、无根钩状褶皱等典型构造现象；微观上表现出眼球构造、书斜式构造、云母鱼构造等。不论宏观还是微观，构造片岩与石英脉都表现出明显的面理置换现象，体现并验证了区域变形变质特征。为了研究石英脉的形成条件，笔者进行流体包裹体测温实验。实验所选取的石英样品均采自研究区构造片岩中与面理S2同期形成的同构造石英脉，较为新鲜，具有良好的代表性。测试结果为包裹体捕获时的温度为350℃，为测得的包裹体的均一温度；估算出捕获压力为225MPa。同时进行了绿泥石成分温度计的相关分析，得出结果绿泥石形成温度范围为327℃~~365℃。验证了包裹体实验结果。同构造化学分泌体中的液相包裹体的测温数据可以作为构造变形相分析的指标，由此得出石英脉形成的温压条件为T=350℃，P=225MPa。反映其形成时的变质相达到了低、中绿片岩相，这与之前通过宏观的构造片岩与石英脉的变形变质特征做出的推断相一致，同时显微镜下对构造片岩与石英脉的观测所显示其变形变质特征也验证了包裹体测试结果。根据野外观察与实验数据以及肖化云等的实验结果，笔者认为研究区构造片岩中广泛发育的石英脉为一种同构造分泌结晶脉，其形成机制与韧性剪切带中物质的溶解、迁移、重结晶作用密切相关。更多还原

【Abstract】 The study area is located in the Tibet Autonomous Region in northern bindingsite is located in the Qiangtang Basin hinterland, North Qamdo plate and Qiang SouthBaoshan plate two plates. In this paper, the distribution of tectonic schist is moreextensive, throughout the maps in most parts of central and western. The era oftectonic schist is ainly Carboniferous–Permian, Tectonic schist mainly experiencedthree deformation and two metamorphism. S2is the rgional foliation. Themetamorphic minerals such as chlorite, sericite are distributed along the foliation S1and S2. The fe-sericite distribution in the S3foliation.First of toughness under the condition of shear deformation, the formation ofshear crenulation cleavage S1, S1is a penetrative regional foliation. in the beat withthe original bedding S0nearly parallel. During which the secretion of syntectonicquartz veins, and the occurrence of a strong flexible flow fold phenomenon. Thesecond phase of deformation is the level of shrinkage, development of regionalpenetration foliation S2. that is axial typecrenulation cleavage. The third phase ofdeformation at the outcrop scale the performance of the thegeniculate fold theformation of the foliation S1, S2, mutually perpendicular to the fold axis F3and F2.With the deformation and metamorphism of tectonic schist, quartz veindevelopmentin the macro quartz porphyroclastic system, syntectonic quartz veins, softflow folds,sharp edges, folds, rootless hook folds typical structural phenomena; Showthe eye structure, the book structures, mica fish structure in the micro. Regardless ofmacro-and micro-tectonic schist and quartz veins have shownsignificant foliationreplacement phenomenon, reflect and validate the regionaldeformation andmetamorphic features.In order to study the formation conditions of quartz veins, I fluid inclusionsthermometry experiments.The experiments selected quartz samples are syntectonicquartz veins formed bytectonic schist of the study area with the same period offoliation S2, more fresh, a good representative. Test results for inclusions trappedwhen the temperature of350°C,that is Homogenization temperatures of fluid inclusions; Estimate the trapping pressure is225MPa. Syntectonic liquid inclusions inthe chemical secretion of the body temperature data can be used as the tectonicdeformation phase analysis indicators, resulting quartz vein formationtemperature andpressure conditions is T=350°C, P=225MPa. The results reflect metamorphicfacies in the formation of quartz veins reached a low greenschist facies. This isconsistent with the inference made before by the macro structure schist andquartzveins deformed metamorphic characteristics, Verify the test results of the inclusionsunder a microscope observations of tectonic schist and quartz veins.According to field observations and experimental data and experimental resultsof Xiao Huayun, I believe that the tectonic schist of the study area, extensivelydeveloped quartz veinssyntectonic secretion crystalline pulse, the formationmechanisms of quartz veins is closely related shear toughness with thesubstancedissolved, migration, recrystallization.更多还原