【作者】 郭威；

【导师】 周鼎武；

【作者基本信息】 西北大学 ， 构造地质学， 2008， 博士

【摘要】 新疆博格达及其邻区处于亚洲大陆腹地,现今的区域地质呈现地块与造山带镶嵌、盆地与山脉共存,构成了独具特色的复杂地质结构构造格局,造就了巨大的中亚成矿域,同时孕育着丰富的能源、矿产资源,既是研究大陆动力学新理论、探索地球科学前沿的最佳天然野外实验室,也是我国矿产资源赋存地之一。因此,通过对博格达造山带、吐—哈盆地、三塘湖盆地的研究和总结,开展新疆博格达山及其邻区中新生代陆内造山作用过程及其形成机制研究,进而探索板内造山机制以及大陆动力学,既具有科学的理论意义,又具有实际的经济意义。论文以板块构造理论、大陆地质和大陆动力学研究的新思想、新认识为指导,在充分认识前人研究成果和区域地质资料的基础上,将发育地层全、地层分布有序、结构构造格架清晰的沉积盆地与结构复杂的造山带密切结合起来,通过对博格达构造带、吐—哈盆地及三塘湖盆地采用地质、地震、钻井等资料相互配合、验证,以构造为主线,从盆地构造解析、造山带构造解析、盆山结合的区域地质解析入手综合分析,对博格达构造带及其相邻盆地板内构造特征及形成演化进行了系统的研究,取得了如下成果:1、依据蛇绿岩、蛇绿混杂岩带的时、空分布,岩浆活动规律和变质作用、构造变形特征综合研究,认为晚泥盆世—石炭纪,阿尔泰山和天山及其相邻区域经历了洋盆俯冲、陆—陆碰撞造山,导致北疆区域洋盆的闭合,形成了博格达构造带及其邻近的准噶尔盆地、吐—哈盆地和三塘湖盆地的褶皱基底,结束了前二叠纪洋、陆转换的板块构造作用过程,开始进入了全新的板内构造作用阶段。2、依据野外剖面观察、地震剖面及钻井资料分析,结合沉积特征及岩浆活动特征,确定了博格达及其相邻盆地的现今盆山共存格局的基本构造样式。博格达山为背冲推覆的复式背斜构造,形成扇形褶皱、冲断构造组合;两侧盆地为受对冲式冲断、推覆构造控制的拗陷盆地,边界断层既控制了构造特征,也控制了盆地的沉积特征。现今的构造格局是新生代形成的。3、确定博格达及其相邻盆地现今的构造特征是喜山构造运动的最终产物,但包容、继承了不同时期的古构造,包括进入板内构造演化以来的海西期、印支期、燕山期各期构造,并确定了其基本构造特征及构造样式。4、通过对博格达山及吐—哈盆地、三塘湖盆地的侵入岩和火山岩同位素定年和岩石地球化学分析,确认其形成时期为二叠纪,侵入的辉长、辉绿岩和中基性火山岩与陆内拉张带或者初始裂谷玄武岩相似;博格达山及相邻盆地中的下二叠统的沉积建造总体上具有由粗到细的正粒序特征,为典型的伸展磨拉石建造;结合准噶尔盆地区域地质资料,依据上述火山—沉积特征与岩浆活动特征,认为博格达山及相邻盆地二叠纪早期为造山后伸展环境。5、综合分析确定博格达山的隆升是经历了海西期、印支期、燕山期和喜山期的多阶段隆升。通过对博格达山两侧盆地的高岩屑含量及重矿物和古流向资料的统计综合分析,限定了博格达山再次隆升的初始时间发生于中侏罗世西山窑晚期,博格达山大幅度隆起是新生代的产物,中新世早期成为博格达山造山的鼎盛时期。更多还原

【Abstract】 Bogda mountain and its adjacent areas are in the hinterland of the Asia continent. Its current regional geology is characterized by mosaic relation between landmass and orogenic zones and coexistence of basins and mountainous chains,which formed a complicated structural configuration,the huge metallogenic province in central Asia with abundant energy and mineral resources.It is not only one of the best natural laboratories for research of continental dynamics and discovery of geoscience,but also it is one of the important metallogenic provinces in China.Studies of the Mesoand Cenozoic intracontinental orogeny and their dynamics in the Bogda orogenic zone and its adjacent areas present practical significances in scientific researches and economy.With the theory of plate tectonics and new knowledge of intracontinental geology and dynamics and on the basis of previous researches and regional geological information,including geology,seismic and drilling data obtained from the Bogda orogenic zone,Tulufan-Hami basin and Santanghu basin,a comprehensive analysis of the structures in those basins and the orogenic zone has been done and a systematic analysis of the characteristics of intracontinental structures in the Bagda tectonic belt and its adjacent regions has been carried out.Following result are obtained from this study:1.Spacial distribution of ophiolite and ophiolite complex,magmatic activities, metamorphism and tectonic deformation revealed that the Altai,Tianshan Mountains and their adjacent regions experienced subduction of ocean-basin,orogenetic collission between continents,resulting in close of the regional oceanic basin in the north Xinjiang and forming the folded basement of the Bogda tectonic zone,adjacent Zhungeer basin,Tulufan-Hami basin and Santanghu basin,ending the process of plate tectonics of transformation between ocean and continent in the Permian period and entering a new period of intracontinental tectonics.2.Based on field geological work,analysis of seismic sections and drilling log, sedimentary characteristics and magmatic activities,the basic tectonic pattern of coexistence of basin and mountains occurring in Bogda area and its adjacent regions is confirmed.The Bogda mountain is present as an anticlinorium structure with thrust nappe,forming a composition of a fan-shaped fold and thrust structures.Basins at both sides of Bogda mountain are down-warped basins controlled by ramp and nappe structures.Those boundary structures made configuration of the characteristics of structures and sedimentation in the basins and the current structural patterns were formed in the Cenozoic era.3.The characteristics of Bodda mountain and its adjacent regions were the final result of the Himalayan movement,including multiphase tectonics in Hercynian, Indosinian and Yanshanian periods in the intracontinental plate,thus making the configuration of the basic features of structures.4.Isotopic dating and lithogeochemical analysis revealed that the intrusive rocks and volcanic rocks in Bogda mountain,Tulufan-Hami basin and Santanghu basin were formed in Permian period,in which gabbro,diabase and basic volcanic rocks are similar to the basalt in intracontinental extensional belt and primary rift.The Early Permian sedimentary configuration in Bogda mountain and its adjacent basins are characterized by normal grading from coarse to fine,being a typical extensional molasse.The regional geological information of Zhungeer Basin and the features of volcanic-sedimentation and magmatic activities indicated that the Bogda mountain and its adjacent basins in the Early Permian period were an extensional environment after orogeny.5.Bogda mountain has experienced multiphase stages uplift including Hercynian, Yindosinian,Yanshanian and Himalayan periods.Comprehensive analysis of the statistics of high debris content,heavy minerals and paleocurrent trend in the basins at both sides of Bogda mountain indicate that the initial time of uplifting again of Bogda mountain was in the late period of Middle Jurassic Xishanyao time the strong upwarding of Bogda mountain occurred in the Cenozoic era and the golden age of the mountain-building was in the early Miocene period.更多还原