Discussing The Evolutive Process Of The Mazha-Kangxiwa-Subashi Suture Zone In West Kunlun Orogen By Stratigraphical Way

There is a important tectonic belt in West Kunlun area,which comes of Gonggeer, pass through Mazha(Sailiyekedaban),Heiqiadaban,Kangxiwa,headwater of Yulongkashi river and extends to Subashi ,and is truncated by Aerjin fault zone in Xiaoerkule late.The tectonic belt is named Mazha-Kangxiwa-Subashi suture zone. It has camber which protrudes to south in plane. It has a huge scope and is joined Mozitage ophiolite in area. Mazha-Kangxiwa-Subashi suture zone concentrates a lot of information of development and evolution about West Kunlun orogen. It controlled magmatic activity,deposition,metamorphic process and ore formation,et al..It has consanguineous relation with orogenic process of West Kunlun. We can realize tectonic evolutive history of West Klunlun area by researching into the suture zone. The research has important significance for ascertaining dynamic mechanism of tectonic framework bringing in West Kunlun orogen.The former geologist seldom studied the tectonic zone by analysis of strata,they often comprehend the attribute and evolutive process of the tectonic zone by cognizing the characteristic of the magma formation, metamorphism and structural evolution in area. So this research regard the time as a cardinal line, regard the strata around the Mazh-Kangxiwa-Subashi suture zone as primary disquisitive object, and more analysed the formative geotectonic backdrop of the tectonic zone by studying the stratal scope of crop out, compositive characters, sedimentary characters, stratal physical source and stratal ages; The research not only collocate these strata into the tectonic system in space time according to plate tectonic theory, but also sequentially make a reversal development about Mazh-Kangxiwa-Subashi suture zone'evolutive processes.During the research of dissertation, author finded Liushitage volcanics which was formed in oceanic island, and it was covered by deep water sedimentary rocks. Dating of this volcanic sample by Rb-Sr isotopes shows the epoch, getting the isochrone age of 563±48Ma, is Sinian. The dating shows that the ocean of Mazha-Kangxiwa-Subashi suture zone was formed in Sinian; Author gathered a lot of lower Silurian weenie fossil organisms in the clastic rocks during fieldwork, made sure that the structural setting of Wenquangou group is residual ocean basin, and found a discordant contact between Luoshigou group which formed at middle Devonian and Wenquangou group which formed at early silurian period,so he think the suture zone attended Caledonian event; Author found many fossils in the strata which formed at Neopaleozoic(late Paleozoic), and compartmentalized and notarize these strata according to sedimentary structural setting, so he think the suture zone began to outspread at Lower Carboniferous again, began to be downgoing at middle Permian, and bilateral land block collided at Trias.Author obtained Sporopollen assemblage which lived at early Trias in Sailiyakedaban group,so make certain that the terminative time of Mazha-Kangxiwa-Subashi suture zone's movement at early Trias.Therefore,this paper thought that Mazha-Kangxiwa-Subashi suture zone experienced Sinian to Early Silurian evolvement of Proto-Tethys and Devonian to Early Triassic evolution of the Palaeo-Tethys ;Tectonic form of the West Kunlun orogenic belt at least was the result of two wilson orogenic cycles. It also believed that the West Kunlun orogenic belt had the tectonic framework characteristic of many island ocean in Paleozoic.