【作者】 王志维；

【导师】 陈刚；

【作者基本信息】 西北大学 ， 固体地球物理， 2009， 硕士

【摘要】 准噶尔盆地北缘山前带和其相邻区域的构造演化事件及其热演化史,不仅是中国西北部古亚洲洋演化和中新生代陆内变形等基础地质构造研究的热点问题,同时也是山前带油气勘探亟待解决的难点问题。本文运用“不整合”构造事件解析、构造热年代学分析与热演化史模拟相结合的综合研究方法,系统分析了准噶尔盆地北缘山前带的区域断裂构造特征、构造层序格架、构造演化事件的峰值年龄分布、构造热演化历史,探索构建了研究区的构造热演化模型。(1)依据野外地质勘察资料和碎屑锆石U-Pb定年数据,结合区域重、磁资料和古生代蛇绿岩、不同类型花岗岩的构造热年代学数据分析,综合揭示了准北山前带相邻区域的断裂构造特征、基底结构组成、构造单元分区和岩石地层单元对比格架,并给出了准噶尔盆地腹部很可能存在前寒武纪结晶基底的一些新证据。(2)依据对准噶尔盆地北部“不整合”事件的时空分布特点以及沉积建造特征的认识,建立构造层序格架,将晚古生代以来发育的岩石地层单元自下而上划分为“盆地浅变质基底和盆地沉积盖层”两大构造层系,并进一步将盆地沉积盖层构造层层系划分为海西期、印支期、燕山期和喜山期四个构造层组,及其相应的T1-T9构造层。(3)依据碎屑岩单颗粒锆石U-Pb定年和裂变径迹分析数据,结合盆地北部区域的蛇绿岩和不同类型花岗岩年龄数据分析,探索建立了研究区构造演化事件的峰值年龄坐标及其与“不整合”事件的对比关系。结果表明,准北古洋盆碰撞闭合事件主要发生在315Ma±,碰撞后陆内裂谷事件的峰值年龄为290Ma±,中新生代多旋回陆内变形事件的峰值年龄主要包括印支晚期的210Ma±、燕山中期的170Ma和145Ma±、燕山晚期的100Ma±。(4)通过磷灰石裂变径迹的热史路径模拟和基于模拟数据的燕山中期古地温梯度恢复,探索构建了准北山前带区域的构造热演化模型,认为研究区存在晚石炭—早二叠世和晚侏罗世—早白垩世两次重要的构造热事件,并主要经历了五个构造热演化阶段:晚石炭—早二叠世高异常型古地温场阶段、中晚二叠世—三叠纪中高平稳型古地温场阶段、早中侏罗世低凹型古地温场阶段、晚侏罗世—早白垩世高凸型古地温场阶段、晚白垩世以来低缓型古地温场阶段。更多还原

【Abstract】 The tectonic evolution and the tectonic thermal evolution history of northen margin of Junggar Basin not only was a hot field in the research on the evolution history of ancient Asian ocean and intra continental deformation in meso-cenozoic, but also was the important question of piedmont zone petroleum exploration. By the integrated study of unconformity event, tectonic thermal chronology and tectonic thermal evolution history, The characteristics of fracture structure, tectonic sequence framework, the pack-age of tectonic event and tectonic thermal evolution history are analysised, and the model of tectonic thermal evolution history of study area is built.(1) Based on the geological field investigation and zircon U-Pb dating, as well as the regional gravity-magnetic date and the tectonic-thermal chronological date of ophiolites and the granites, the characteristics of the faulted structure belt, basement component, tectonic-unit division and rock-stratigraphic units in Northen Junggar Basin were revealed. Also, some new evidences of existing Precambrian Crystalline Basement in Junggar basin were presented.(2) By the distribution characteristic of unconformity event on the northen Junggar Basin, tectonic sequence framework is built. Furthermore, the rock-stratigraphic unit since late paleozic is divided into two tectonic layer series, "basin low metamorphic basement and basin sedimentary cover", and basin sedimentary cover is divided into hercynian, indo-chinese epoch, Yanshan geological period and himalayan period stratigraphic formation and its corresponding nine tectonic layer.(3) Through the analysis of the single grain zircon u-pb ages dating and the fission track dating, combining the dating of tectonic thermal chronology of paleozoic ophiolite and diffrernt type of granites in the northen basin. The relationship of the peak-age coordinate and the unconformity tectonic event is revealed. The result indicate that the subduction and collision of ancient ocean basin closure event happened in 315Ma±, the peak-age of the extension event of continental rift vally after collision is 290±, the peak-ages of deformational event of polycyclic continental rift is 210Ma±in the late indo-chinese epoch, 170 Ma±and 145Ma±in the medium-term of Yanshan geological period, 100Ma±in the late of Yanshan geological period.(4) The model of the tectonic thermal evolution history on northen margin of Junggar Basin is established by the AFT simulation of thermal evolution history and the recovery of the paleo temperature gradient. The result revealed that the thermal evolution history in the study area include five stages: high abnormal type of paleo-geothermal field stage in late carboniferous to early permian, mid-high stable type paleo-geothermal field stage in mid-late permian to triassic, low concave type paleo-geothermal field stage in early-middle jurassic, high convex type of paleo-geothermal field stage in late jurassic to early cretaceous and slowly type of paleo-geothermal field stage after late cretaceous.更多还原