青藏高原羌塘-三江地区残留微陆块

综合研究历年区调成果,发现西藏羌塘-三江地区残留若干微陆块,有相同或相似的岩石组合,主要变质期(1800Ma)变质相、构造变形性相近。原是一个有成生联系的微陆块群,有层无序、顶底不全,多系构造接触的中高级变质岩系。历年建立的羌塘戈木日岩群,三江地区宁多岩群、雄松岩群、石鼓岩群、苍山岩群、哀牢山岩群、吉塘岩群、崇山岩群、大勐龙岩群等12个岩群,依据区域对比、上覆地层及同位素年龄,统归古元古界(Pt1),构成本区早期大陆地壳-结晶基底。羌塘 三江残留微陆块群南接越南"印支地块",北邻西域陆块,东邻扬子陆块,南邻冈底斯 察隅陆块,是介于欧亚板块与印度板块之间的接合部位,具有独立地质构造演化及成矿特征的构造域,建议称为"羌塘-三江古-中特提斯构造域"。

THE RELICT MICROCONTINENT IN QLANGTANG-SANJLANG AREA OF QING-ZANG PLATEAU

According to the comprehensive study on the regional survey results in many years, we discovered that there are some relict microcontinents in the Qiangtang-Sanjiang area of Xizang, which have the same rock assemblage, similar metamorphic facies and structural deformation quality of main metamorphic period(1 800 Ma). They are a group of microcontinents that have the genesis relationship, which are originally formed by the middle or high degree metamorphic rock series with the structural contact and incomplete top and bottom. There are 12 rock groups set up in many years, ie. Gemuri Rock Group in Qiangtang, Ningduo Rock Group, Xiongsong Rock Group, Shigu Rock Group, Cangshan Rock Group, Ailaoshan Rock Group, Jitang Rock group, Chongshan Rock Group and Damenglong Rock Group in Sanjiang area. In present paper, we put all of them into the Paleoarchean, which formed the early continental crust -crystaline basement in this area.The relict microcontinent in Qiangtang-Sanjiang area is connected southward with the "Indosinian Massif", neighbouring northwards to the Xiyu Landmass, eastward with the Yangzi Landmass and southward to the Gangdisi-Chayu Landmass. It is the connection part between the Eurasian plate and the Indian plate, which has the independent characteristics of geological structural evolution and the structural domain of metallogenetic characteristics. We suggest calling it "Qiangtang-Sanjiang paleo-middle Tethys structural domain".