【作者】 李博秦；

【导师】 姚建新；

【作者基本信息】 中国地质科学院 ， 古生物地层学， 2007， 博士

【摘要】 西昆仑有一条重要的构造带,即麻扎-康西瓦-苏巴什结合带,该结合带由公格尔经麻扎(赛力亚克达坂)、黑恰达坂、康西瓦、玉龙喀什河上游向苏巴什延伸,至硝尔库勒湖附近被阿尔金断裂截断,大致呈向南凸出的弧形展布,区域上与东昆仑木孜塔格蛇绿岩相连,规模宏大。它浓缩了西昆仑造山带发展、演化的大量信息,控制着麻扎-康西瓦-苏巴什一带的岩浆活动、沉积作用、变质变形作用甚至成矿作用等,与西昆仑造山过程息息相关。通过对该带研究可以了解西昆仑地区的构造发展历史,为探讨西昆仑造山带构造格局的形成及动力学机制研究提供依据。前人主要是通过岩浆建造、变质变形、区域构造演化等特征来认识该结合带的属性及演化过程的,很少从地层角度对该带进行研究。因此本文以时间为主线,以出露在麻扎-康西瓦-苏巴什结合带附近的地层为主要研究对象,对该区地层的出露范围、组成特征、沉积特征、物质来源、时代等进行了研究,进而分析了其产出的大地构造背景;同时以板块构造理论为基础,对研究区的地层进行了相应的时空构造配置,反演了麻扎-康西瓦-苏巴什结合带的演化过程。在本论文的研究过程中,作者在结合带中发现了柳什塔格洋岛火山岩及与其相伴的深水沉积岩,对火山岩进行了Rb-Sr等时线测年,得出563±38Ma,从而将该带的演化时限探究到了震旦纪;在温泉沟群中采集到了大量微体古生物化石,将该套地层确定为残留洋盆沉积,发现了中泥盆世落石沟组与早志留世温泉沟群不整合界面,这些发现和认识表明该结合带经历了加里东造山运动;在晚古生代以来形成的地层中采集到了大量古生物化石,对这些地层进行了沉积构造背景划分和厘定,认为该带从早石炭世开始又发生了伸展、扩张,从中二叠世开始俯冲、消减,三叠纪两侧陆块碰撞造山;在赛力亚克达坂群磨拉石沉积中采集到了早三叠世孢粉化石组合,认为该带活动结束的时间应该在早三叠世。由此本文认为麻扎-康西瓦-苏巴什结合带经历了震旦-早志留世的原特提斯洋的演化和中泥盆世-早三叠世的古特提斯洋的演化;西昆仑造山带目前构造格局的形成,至少是两个威尔逊造山旋回的结果。同时还认为,西昆仑造山带在古生代具有多岛洋构造格局的特点。更多还原

【Abstract】 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.更多还原