【作者】 张义；

【导师】 李亚林；

【作者基本信息】 成都理工大学 ， 构造地质学， 2008， 硕士

【摘要】 定日-岗巴盆地位于西藏西南部,是著名的特提斯-喜马拉雅构造带重要组成部分,也是青藏地区具有勘探前景的含油气盆地之一。同时,作为大陆碰撞与造山作用研究的典型地区,定日-岗巴盆地由于受造山作用的影响,使盆地遭受强烈地改造、变形复杂,因此盆地构造变形与改造是定日-岗巴盆地需要深入研究的重大构造问题,也是盆地油气远景评价的关键问题。针对定日-岗巴盆地研究中存在的构造问题,论文选择定日-岗巴盆地西部为研究对象,在充分收集及利用前人研究成果基础之上,以精细的路线地质调查为基础,以构造变形分析和石油地质新理论为指导,以详细的构造解析为手段,从盆地现今结构、构造的几何学入手并结合已有的地球物理资料,分析盆地基底构造基本特点、盆地盖层构造格架。同时,以几何学、运动学和动力学全面构造解析为基本方法,查明各种规模构造变形形迹(褶皱、断裂、节理、面理和线理等)的产状、性质、规模、分布和组合规律,开展变形期次、物质组成、几何样式和力学性质等研究,对盆地构造单元进行划分。在此基础上,全面考虑收缩、伸展、走滑构造体制在盆地构造变形过程中的作用和演化规律;区分不同构造层次的构造样式和变形机制,分析不同期次构造变形的叠加、置换及其复何效应,建立构造变形序列和构造模式。进而运用构造应力场分析的方法,恢复确定盆地褶皱构造的变形应力场。最终,结合盆地构造变形强度、岩浆—火山作用、盆地地层分布与出露特征对盆地构造改造强度进行划分,对盆地西部的油气有利构造保存单元进行了预测,从构造变形与改造的角度为定日-岗巴盆地油气资源潜力评价和勘探区块的选取提供依据。论文主要得出以下几点进展与认识:1.以构造变形为基础,对定日-岗巴盆地西部构造单元进行了划分,将研究区划分为北部断褶带、中部复式褶皱带、南部拆离构造带三个一级构造单元,又将北部断褶带进一步划分为北部复向斜带和南部复背斜带、中部复式褶皱带划分为北部复向斜带和南部复背斜带。2.通过对研究区详细的构造解析,建立了盆地西部构造变形序列。提出自中生代晚期—新生代以来盆地经历了4期构造变形:第一期变形为中深层次顺层剪切机制下产生的紧闭同斜褶皱;第二期为中层次挤压体制下产生的逆冲断裂与褶皱构造;第三期变形为沿盆地内不同时代地层界面或同一地层不同岩性界面发育的伸展拆离构造;第四期变形为新生代晚期东西向伸展机制下产生的南北向地堑构造。其中第二期变形为盆地主导构造样式,且褶皱构造形态好、规模大,为盆地有利圈闭构造。3.通过盆地褶皱构造应力场初步分析结果表明,盆地变形以NNE-近SN向水平挤压为主,SN向发生收缩应变,EW向伸长,褶皱运动轴直立向上,为纵弯褶皱。4.通过构造改造强度分析,认为盆地西部那加-雄如-帕尔瓦-强木果地区和吉隆-沃马-恶拉-博尔杰拉加地区构造变形较弱,为油气有利构造保存单元。更多还原

【Abstract】 The Dingri-Gamba basin, an important component of the world-famous Tethys-Himalayan tectonic zone, is located in the southwest part of Tibet. As a representative area of the international studies on continental collision and orogenesis, one of the best explorative prospect petroliferous basins in Tibet, it had experienced complicated deformation extremely. With the intense orogenesis influence, the basin suffered from intense reforming, which is related to the valuation of oil and gas resources directly. The structural deformation and reform of basin is the significant tectonic problem about petroleum geology and the oil-gas appraises in the Qinghai-Tibetan Plateau.In order to solve the tectonic problems existed in the Dingri-Gamba basin research, the thesis takes western part of the basin as priority study area on the basis of collecting and making use of prevenient research results, as well as accurate routes of geological investigation. Taking structural deformation analysis and new theories about petroleum geology as guide, detailed tectonic deformation analyses as method, the thesis begins with the geometry about present structures and tectonics, make use of the prevenient geophysical data, analyse the fundamental characteristics about base structure and the structure of overlying strata of the basin. Meanwhile, by taking the comprehensive tectonic analysis method concerning the geometry , kinematics and dynamics, this paper finds out various scale structural deformation pattern(fold, fault, joint, foliation and lineation etc.), and their current properties, scale, distrubution and combination rule, carrys out the study about deformation stages, component, geometrical pattern and mechanical properties ect. And the cover tectonic units were divided into several rational units. On the basis, contracting, extending, and srike-slipping are considered fully on the process of basin structural deformation. By distinguishing the structural sequences and deformation mechanism in different structural level, analyzing the effects of structural replacement and composition in different time, the structural deformation sequences and the structural patterns were built. And then the stress-field of the fold structures in the basin was ascertained after structural strain analysis. Finally, combined with the basin structural deformation , magma-volcano effection and the stratum characteristics, the author got the tectonic reform intensity, ascertained the areas which are propitious to gas-oil preservation in west part of the Dingri-Gamba basin, and provided scientific basis for gas-oil resources potential valuation and prospecting areas in Dingri-Gamba basin from the aspect of tectonic deformation and reform systematically.The paper mainly draws following several conclusions:1. Divided the research region into three first-grade structural units by analyzing the effects of structural deformation: northern thrust belt, central compound-fold belt, southern detachment structure belt, further, divided the northern thrust belt into nothern synclinorium belt and southern anticlinorium belt, central compound fold belt into northern synclinorium belt and southern anticlinorium belt.2. The study also suggested that the basin has experienced four tectonic reformations episodes since late Mesozoic to Cenozoic. The first is closed to tight folds result from middle to deep shearing mechanism along the delamination. The second is the thrust fault and fold structure caused by middle layer compression system. The third phase deformation is normal fault that developed along the formation interface from different times or the same stratum with different lithology in the basin. The fourth phase is that the NS graben structure was produced by EW expanding mechanism in late Cenozoic. Thereinto, the second deformation is the leading structural form in the basin, and the form of fold structure is fine and large, which is an advantageous trap structure.3. The study result about stress field of fold structure indicates that the deformation in basin is dominatingly trending NNE to near SN direction extrusion. The SN direction takes contracts strain, EW direction happens to extend, the fold motion axis stands straight. Therefore, the fold belongs to buckle fold.4. By the analysis of structural deformation intensity, the author think that the research area, Na jia-Xiong ru-Qa er wa-Qiang mu guo area and Ji long-Woma-E la-Bo er jie jia la area, is propitious to gas-oil preservation.更多还原