【作者】 王宗秀；

【导师】 马宗晋；

【作者基本信息】 中国地震局地质研究所 ， 构造地质学， 2003， 博士

【摘要】 造山带虽然经过近代一百多年的研究，但仍一直是地质科学研究的前沿课题。特别是80年代以来，大陆造山带成因研究已成为固体地球科学最主要前沿领域之一。迄今为止，对不同类型造山作用与造山带的深入研究，在现代地学研究中仍占有重要的地位。作为新生代典型陆内造山的博格达山链，以其独特的造山面貌而有别与其它陆内造山带。针对这种“强造山”，“弱表现”的特点，本文从岩石学(沉积岩、火山岩、岩浆岩、变质岩)、构造地质学、年代学、深部地球物理等多学科相结合研究角度入手，对博格达山的造山活动、山体演化历史等成山过程进行了较为系统的研究，将博格达山链的成山过程划分为三大阶段，提出了博格达山新生代再造山的造山模式。同时对新生代的造山动力学问题进行了讨论，并提出了远程效应与岩石圈深部约束联合作用的认识。 在本文的绪论部分，在对以往研究成果系统查阅及综合分析基础上，对研究区的研究基础进行了详细论述，对前人的工作、研究成果进行了归纳总结，并就研究区及邻区所存在的地质问题以及争议点做了阐述。 在对前人资料系统地综合分析基础上，对新疆北部地区(包括东天山)二叠纪以前的古构造环境进行了概括分析，针对许多存在的地质构造质疑问题，提出新疆北部所出露的众多蛇绿岩带可能是产于古生代形成的同一个大洋的观点，即新疆北部可能只存在一个大洋——准噶尔-天山洋(隶属古亚洲洋一部分)。并以此为构造背景，对新疆北部的大地构造单元进行了划分。划分出两个被动陆缘(阿尔泰被动陆缘带、塔里木北缘被动陆缘带)和三个弧盆带(东准噶尔泥盆纪弧盆带、北天山石炭纪弧盆带、南天山泥盆纪弧盆带)(见下表)。同时，在只存在一个大洋的前提下，对造山前的古构造演化进行了讨论，提出了三个演化阶段：①震旦-寒武纪的陆壳拉张阶段；②奥陶-志留纪的洋盆形成阶段；③泥盆-石炭纪的洋盆消减阶段。并认为大洋的消减为向南、向北对称消减。而且整个新疆北部地区，古构造演化是一种不均衡的、复杂的构造变动。 对博格达山(研究区)区域的古构造环境认识，目前存在有限洋盆、裂陷槽、裂谷、岛弧之争。针对这个长期存在的争议问题，本文在进行部分地球化学分析基础上，并结合区内王宗秀:博格达山链的造山活动及山体形成演化 己有的岩石学、地球化学等方面资料综合分析基础上，认为博格达山地区在造山之前，经历 了裂陷槽、岛弧等复杂演化历史。其中在泥盆纪时期为一裂陷槽，随着大洋的消减，于石炭 纪演化成岛弧环境。. 针对博格达山链在整个天山造山带中的特殊构造位置，以及以往对该区研究的薄弱点， 从构造变形角度出发，对山链的变形构造进行了较细致的野外和室内综合研究，首次在博格 达山区发现了韧性剪切变形带，并由此揭开了博格达山初始造山活动的神秘面纱。通过宏观 和微观变形构造的详细分析研究，确定了博格达山韧性剪切变形带的变形机制、变形期次、 构造式样。认为博格达山韧性剪切变形带的主变形为南北向剪切收缩，其后又经历了伸展剪 切和走滑剪切，是一条多期演化的复合型韧性剪切变形带。韧性剪切变形带的形成温度不大 于400℃，是一条低温剪切带，现今出露的部位为下部构造层次的中上部位以上部分。运用最先进的测试手段(错石SH班MP测试)，对同构造期长英质脉体中错石进行了探索性分析研究，获得了较可靠的剪切带形成的年代学证据—晚石炭世，是年代学研究中的一种尝试，也为同样地质环境中构造年代学研究提供了一种新的思路。在上述综合研究基础上，提出晚石炭纪为博格达山初始造山的起始时间，初始造山的主要构造表现为南北向韧性剪切收缩应变。韧性剪切带的形成为洋壳消减殆尽，板块拼贴，岛弧带内发生造山活动的产物。 从沉积学角度入手，通过沉积物类型、沉积层序、构造地层层序、古水系、物源等方面数据综合分析研究，对研究区的中生代地质环境进行了恢复，认为整个东天山地区在中生代期间整体处在伸展的大地构造背景下，并在侏罗纪期间形成吐哈与准噶尔以及塔里木相通的 “泛湖”。晚古生代石炭纪末的洋壳消减和板块拼合使天山地区整体隆起，海西运动晚期结束了残留海相沉积，形成了与准噶尔盆地相通的吐哈、伊犁、三塘湖、柴窝堡等盆地。三叠纪沉积盆地分布广泛，尤其是晚三叠世，湖盆范围扩大。侏罗纪整个天山地区相对稳定，整体沉降，三塘湖盆地、吐哈盆地、柴窝堡盆地与准噶尔盆地连成一片，形成泛湖泊一河流-沼泽沉积背景，焉省盆地、库米什盆地可能与塔里木盆地相连，形成了广泛的湖泊、沼泽。由于中侏罗世末期的燕山运动，博格达地区开始不断隆升，但幅度不大，因此将吐哈盆地与准噶尔(准东)两盆地暂时“分割”开来，在白坚纪初期，又重新恢复的区域伸展背景下，形成湖泊一河流相坳陷型盆地，白至纪中后期吐哈盆地和准噶尔盆地被博格达山彻底分割开来。认为伸展机制可能源于板块拼贴后的应力松弛和地壳变形的弹性回跳。 从博格达山链中广泛发育的逆冲一推覆构造入手，通过褶皱与断层的配套与组、逆冲推覆构造的发展序列、变形构造组合样式等综合系统研究，更多还原

【Abstract】 Although the study on the orogen has been continuing for about 100 years, it is still the hotspot in geology. Especially from the 1980’s on, the mechanics of the orogens have become one of the key fields in the solid earth science. The Cenozoic Bogeda mountain chain taken as the representative intracontinental orogen is different from other intracontinental orogens by its especially erogenic process. In allusion to the characteristics of "strong orogeny" and "weak exhibition", the much systemic researches on the orogeny, evolution of Bogeda mountain have been carried out by means of the structural geology, petrology (sediment rocks, volcanic rocks, igneous rocks and metamorphic rocks) and chronology. The re-orogenic model of Bogeda Mountain is put forward. And the Cenozoic dynamics of Bogeda Mountain has been discussed. Based on these, the point of view that the far range effect of collision between Indian Plate and Eurasian Plate and deep structures of lithosphere together control the orogenic process is brought forward.Based on the systemic and comprehensive analysis of the data of many other workers, the tectonic setting of the northern part of Xinjiang (including eastern Tian shan) before Permian is analyzed synoptically. For resolving the many questions about the northern part of Xinjiang, the point of view that the many ophiolites outcropped in the northern part of Xinjiang maybe belong to one ocean basin is put forward, i.e. maybe there is only one ocean-Junggar-Tien Shan Ocean (part of paleo-Asian Ocean) developed in the northern part of Xinjiang. Based on this point, the tectonic units of northern part of Xinjiang are plotted out. There are two passive continental margins (Aletai passive continental margin and northern passive continental margin of Tarim) and three Arc-Basin belts (the eastern Junggar Arc-Basin belt in Devonian, the northern Tian Shan Arc-Basin belt in carboniferous and the southern Tian Shan Arc-Basin belt in Devonian). And in the premise of only one ocean, the tectonic evolution of northern part of Xinjiang is discussed, four evolution stages are put forward. They are (1) the extension of continent crust during Sino-Cambrian period; (2) the formation of oceanic basin during Ordovician -Silurian period; (3) the subduction and closure of oceanic basin during Devonian-Carboniferous period; (4) the intercontinental extension during Permian-Triassic period. And the ocean floor subducted symmetrically to the south and north respectively.There are many disputations about the geological setting of the Bogeda Mountain, such as small oceanic basin, aulacogen, rift or Island-Arc and so on. Based on the geochemical analysis combining other data, the author thinks that in Devonian time one aulacogen developed in the Bogeda Mountain region, and with the closure of the oceanic basin, the aulacogen developed into one Island-Arc.For the first time, the ductile shear zone has been found in the Bogeda Mountain, and this discloses the magic veiling of the initial orogeny. By the detailed analysis on the micro-scale andmacro-scale structures, the mechanics of the ductile shear zone, the phases of deformation and structural styles of the Bogeda Mountain are ail confirmed. The main deformation of the ductile shear zone was the north-south shortening, and later the extension and strike-slip movement were main ways of deformation, so the shear zone was a superimposed ductile one. Using the most advanced dating method-zircon SHRIMP dating, the author obtained the more reliable age data of the formation of the ductile shear zone, i.e. later Carboniferous. So the author thinks that the time of the initial orogeny of Bogeda Mountain was later Carboniferous, and the main mechanics of deformation was the north-south shear shortening. The formation of the ductile shear zone was the results of the closure of the oceanic basing accretion of plates and orogeny in Island-Arc zone.By studying the sediment sequence, the types of sediment material, tectonstratigraphy, paleocurrent and source region, the reconstr更多还原