Research Of Metamorphic Rocks And Metamorphism In The Gemuri Area, From Central Qiangtang, Northern Tibet, China

There are many distribution of the large area of low-grade metamorphic series in the Gemuri area, including the low-grade metamorphic layered series from zhan-jin rock group(Hunan-shan petrofabric,Tongbei-liang petrofabric,Jiliang-shan petrofabric,Xiema-ri petrofabric),low-grade metamorphic mafic intrusive assemblages(dike),metamorphic ophiolite melange assemblages, and also developed an order of high-pressure metamorphic belt of eclogite and garnet muscovite schist rock combination, which is tectonic contact with zhan jin rock group. The is a ductile deformation zone of mylonite and mylonite rocks in the contact zone.In order to study the causes and tectonic significance from the low-grade metamorphic series and high-pressure metamorphic belt in the Gemuri area. We study the main line of high-pressure metamorphic belt, and ascertain the metamorphic rocks units of different types of combination,spatial distribution of cases, and carify the various elements of the original rock characteristics and formation environment of the construction. Then Combined with the study of eclogite and garnet muscovite schist from the high-pressure metamorphic belt, we initially distinguish the metamorphism phase,metamorphic condition in the different metamorphic units,and so on. Then we will have a final discussion about the tectonic evolution history in the Lungmu Co- Shanghu plate suture. The results obtained are as follows:1. Qiangtang Gemuri area's metamorphic rocks are mainly composed by the low-grade layered rock series, low-grade metamorphic mafic intrusive assemblages, metamorphic ophiolite melange assemblages, the high-pressure metamorphic rocks assemblages (high-pressure metamorphic belt) . 2. There is an greenschist facies metamorphism in the the low-grade layered rock series, low-grade metamorphic mafic intrusive assemblages, metamorphic ophiolite melange assemblages.3. High-pressure metamorphic zone experienced -> lawsonite - glaucophane schis facies before the peak period -> eclogite facies in the peak period -> glaucophane schis facies after the early period of peak -> epidote amphibolite facies after the late period of peak.4. The high-pressure metamorphic zone experienced the formation of eclogite in the early time , the formation of high-pressure metamorphic zone, the tectonic emplacement process of high-pressure metamorphic zone, ductile deformation zone is the important mechanism in the appearing of high-pressure zone.5. Tectonic evolution history in the sutures zone was divide into the metamorphism before the collision,the collision metamorphism, metamorphism after collision. Metamorphism before the collision resulted in the formation of eclogite;the collision metamorphism was widely distributed in the research area, and formed the active continental margin of a metamorphic series;metamorphism after collision was a process that high-pressure metamorphic rocks were exposed at the surface, and accompanied by blue-greenschist facies metamorphism occurred. In the suture zone. the tectonic evolution history of metamorphic rocks reflect the whole process of Paleo-Tethys Ocean closure.