【作者】 张雪亭；

【导师】 莫宣学；

【作者基本信息】 中国地质大学（北京） ， 矿物岩石矿床学， 2006， 博士

【摘要】 青海位于青藏高原东北部、泛华夏陆块群的中西部,东特提斯的北部。显生宙以来处于劳亚大陆与冈瓦纳大陆之间,纪录了古亚洲洋、古特提斯洋的演化历程。在中国大陆地质演化和各大陆块群的沧桑巨变中,它是连接塔里木、阿拉善、扬子、羌塘等几大陆块的重要纽带,占居重要的位置。 青海及邻区地质作用记录表明:青海的板块构造体制始于寒武纪,大地构造格局成型于三叠纪。统一陆壳也是显生宙以来逐步形成的:主要经历了加里东和华里西-印支两大构造阶段。自北而南由8条不同规模的板块、陆块结合带及其夹持的陆块镶嵌而成。这些微陆块在各自的发展演化过程中因动能巨大,势能较小,活动性和不稳定性明显,不同阶段可能分属不同的大陆块体或者不同的板块,具有明显的动态变化特点。因此,对青海这样一些微陆块发育的陆壳结构的大地构造格局研究而言,地球演化的阶段性规律在分析不同时期洋陆布局、划分和建立大地构造单元具有更重要的意义。此外,由于青海地壳结构的多条块拼合特点,区分不同性质的结合带,确定主构造期与主演化阶段成为建立构造格架的基础。 本文结合《青海省地质图与大地构造图编图》项目,以板块构造理论为指导,遵循“将今论古”的比较学原理,在充分搜集青海及邻区区域地质资料和板块编图成果,特别是最近完成的区域地质调查资料基础上,采用大地构造相、岩石构造组合、古地磁及生物古地理分析、综合地质学特征对比等多学科相融合的方法,经综合研究而成。 通过研究取得如下主要认识与结论: 1、大地构造相和岩浆岩构造岩石组合是研究板块构造格架和精细划分构造单元的有效方法与重要基础;敛合盆地的组合类型与岩浆侵入规模所反映的消失洋盆大小是鉴别板块构造结合带级别与类型的宏观标志;结合带的断裂带特征、蛇绿岩类型、附近地质体变质变形特征、深部地球物理特征和断裂切割深度、地球化学特征、所包含的演化阶段、两侧盆地发育特点、生物区系特征、俯冲极性、残留洋盆发育程度、岩石学特征等11项综合特征,是区分不同结合带性质的主要标志;主构造期思想是建立区域大地构造格架的灵魂。 2、通过沉积特征和构造变形特征分析,首次建立了青海大地构造相体系,划分为25个大地构造相,归并为7个相类。新建残留洋盆相,提出一个特殊相类。为青海省板块更多还原

【Abstract】 Qinghai is geographically located in northeastern Qinghai-Tibet Plateau and tectonically in the mid-western part of the Pan-Cathysian Block Group and the north part of eastern Tethys. It is laid between the Laurisia land and the Gondwanaland during the Phanerozoic and recorded the evolutional process of Palaeo-Asia Ocean and Palaeo-Tethyan Ocean. As a junction among Tarim, Alashan, Yangzi and Qiangtang blocks Qinghai region played an important role during the geological evolution of Sino-continent and relavant continental blocks.Geological records in Qinghai and its adjacent regions indicated that the plate tectonics region in Qinghai started from the Cambrian and the tectonic framework, essentially formed in the Triassic. The Qinghai crust was gradually collaged during the Paleozoic and mainly underwent Caledonian and Hercynian-Indosinian tectonic events. It can be divided into eight units, consisting of plates, continental blocks and sutures in different scale. These tectonic units varied with time during the tectonic evolution. So it is important to distinguish the differences in tectonic framework among various tectonic stages, and to determine main tectonic stage during the evolution history of Qinghai.According to plate tectonic theory and the principle of "compare the past with the present", this thesis compiles a great deal of data of regional geological mapping and sample analysis, and focus on the tectonic framework of Qinghai region.The conclusions are reached as follows:1. The tectonic facies and petrotectonic assemblages analyses are the efficient methods and key basis for the research on principal tectonic framework and classification of tectonic units. The size of disappeared oceanic basin, which could be estimated from the type of petro-assemblage in compressive basins and the scale of intrusions, serves as a macroscopical indicator to recognize the scale and type of tectonic belts. Eleven indicators, such as the features of fault zone, the type of ophiolites and so on, have been used for distinguishing the nature of tectonic conjunction zones. The idea of determining the major tectonic epoch is the key point to set up regional tectonic framework.2. Based on analysis of sedimentary and deformational features, this work set up the first tectonic facies system of Qinghai region, which is divided into 25 tectonic facies and ranked into 7 types. Remnant oceanic basin facies was newly set up. It provided valuable basin analysis result for establishment of the plate tectonic pattern and prediction of mineralization.3. Based on systematic study of Bayan Har basin, the thesis has brought forward an opinionthat the basin was a typical remnant oceanic basin, which was developed on a "soft" basement during later Permian to Triassic and occurs as main part of northern Tethys oceanic relics, together with the Jingyu lake-eastern Kunlun Suture Zone, western Jinwulan- Jinshajiang Suture Zone and Longmenshang fault zone.4. The petrotectonic assemblages of igneous rocks in Qinghai have been systemically studied and a space-time framework of igneous rocks has been set up.The intrusions have been divided into 11 petrotectonic assemblages, 20 tectonic magma epoch and 6 types of assemblage based on a great deal of isotopic dating of the petro-assemblages combined with regional geology and tectonic environments. The characters of the petrotectonic assemblages indicate that the Eastern Kunlun orogenic belt was mainly as a result of the subduction and closure of the Animaqing-Bayan Har-Jinshajiang oceanic basin, forming the largest magma belt in Qinghai. The Variscian-Indian orogeny was the main orogenic cycle and tectonic epoch in the region studied.5. The principal framework of Qinghai tectonics consists of two sutures, one ocean and two massifs. The southern Kunlun suture zone is considered as the main tectonic suture, and the Jinsha River belt as secondary suture. The Bayan Har remnant ocean basin as the main part of the Palaeo-Tethyan ocean relics, which divide the Qinghai into two parts: Xiyu massif, western part of the Pan-Cathysian Continental Blocks, in the north, and the Tanggula-Qiangtang massif in the south.更多还原