【作者】 张忠义；

【导师】 吴淦国； 郭敬辉；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2005， 博士

【摘要】 在广泛收集前人研究和工作成果后,开展了野外和室内有目的研究;综合应用构造解析、盆地分析及岩石学研究的理论和方法,从时空尺度上对鲁西中新生代以来的伸展构造进行了研究。加深了对中生代以来鲁西及其周边地区大陆构造演化的理解。研究表明,鲁西中生代南北向的伸展活动开始于早侏罗世(约200Ma);首次应用同构造地层倾角及盆地分析的方法,对鲁西中新生代地壳伸展变形过程进行了确定和反演,并提出鲁西中生代的地壳伸展变形是以中低角度铲式正断层为组合特征,同时发育近南北向的走滑转换断层,代表的是一种强伸展变形;总体具简单剪切的几何特征,形成伸展拆离型盆地;新生代地壳伸展变形以高角度正断层为组合特征,这与现今地表所见高角度正断层一致;地壳伸展变形强度弱,总体具有纯剪变形的构造几何特征,形成裂谷型盆地。伸展作用与岩浆作用的关系研究表明,鲁西地壳的伸展变形及盆地的充填部分伴随着区域上的岩浆活动;白垩纪地层与伸展有关的旋转角度最大,显然该阶段地壳的伸展减薄最强烈,也是岩浆活动最强烈期,大约为110-130 Ma;中生代岩浆活动滞后裂陷沉积约25 Ma;而且与岩浆活动相比,鲁西伸展活动波及范围更广,时间跨度更大;就这层意义上来说,排除了伸展构造与岩浆活动有成因上的联系,但区域上的岩浆活动多发生于伸展活动强烈期,说明二者是相互影响和促进的。综合分析研究提出,中生代南北向伸展活动的发生与早期挤压增厚的地壳,因重力失稳发生侧向扩展活动有密切的联系;而与板块运动有关的构造偏应力是新生代地壳伸展变形的主要驱动力;而地壳的结构亦对伸展变形过程起了重要控制作用。从中生代到新生代鲁西岩浆活动总的演化趋势是越来越基性,而且新生代玄武岩缺少陆壳物质的混染,可能的解释是新生代幔源的岩浆快速通过中生代减薄了的地壳的结果。鲁西中新生代大陆地壳伸展变形模式的变化,是伸展样式随时间变化的实例。同构造地层倾角分析及伸展裂陷沉积显示,鲁西中新生代伸展强度及伸展量都表现出北部强或大于南部,暗示地壳的伸展减薄在区域上可能是不均的;这与现代地球物理资料反映出的鲁西的地壳岩石圈厚度大于其北部相一致。更多还原

【Abstract】 In light of the previous work, the techniques of structural examination, basin analysis and petrology study have been used to deal with the Mesozoic –Cenozoic extensional tectonics in the west Shandong; determine the time of onset of crustal extension; unravel the structure and its style, change in magnitude, and deformation model of extension; clarify the process of continental extension. And the tectonic driver for extensional event also has been discussed. This work can help to gain a further knowledge of complex tectonic evolution of west Shandong and its adjacent areas in eastern China. Detailed studies revealed that the time of the the beginning of N-S regional extension is at ca. 200 Ma. And Mesozoic extension is characterized by gently to moderately dipping listric faults style and displacement along these faults is transferred from one to the next along N-S strike-slip faults. This structural style displays high-magnitude extension, has overall tectonic geometry of simple shear and forms detachment basins. However, Cenozoic extension is characterized by high-angle normal faults style and some of them bound the present basins. This structural style displays low-magnitude extension, has overall tectonic geometry of pure shear and forms rift basins. Crustal extension activities were partly concurrent with regional magmatism since Mesozoic in west Shandong province. Experienced maximum rotation of Cretaceous sedimentary sequences related to extension is evidence for the most extensive crustal stretching and thinning from 110 to 130 Ma. The Mesozoic extension preceded magmatism by 25 Ma. And compared with magmatism, extensional activities was long-lived and occurred in more widespread area, to the extent that preclude a genetic link between local magmatism and extension. But the observation that pulses of magmation generally coincided with the peak extensional strain rates suggests that the two processes reinforced each other. The integrated studies support the concept that Mesozoic S-N extension activities result from the lateral spread of the early gravitationally unstable thickened crust. But the deviatoric stress caused by the plates motions is the main driver for the Cenozoic extension. And the crustal structure change over time also plays an important role in the tectonic process. The rapid更多还原