【作者】 王建强；

【导师】 刘池阳；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2010， 博士

【摘要】 沉积盆地与造山带是大陆地质研究中最基本的两大构造单元,作为矛盾对立统一的两个方面在大陆结构中相互依存,往往于统一的构造框架和动力学体制下形成和演化；从盆地中揭示造山过程,从造山带中探索盆地的形成机制,恢复不同时期盆山耦合系统及动力转换机制,必将更加有效、更深入的探索大陆造山带和沉积盆地形成、演化的地球动力学机制、物质迁移规律等。以沉积盆地“整体、动态、综合”研究的三原则为指导,运用改造盆地、原盆面貌恢复及盆山耦合等研究思路,综合地质分析法、矿物年代学方法、物源分析方法、剥蚀厚度恢复方法等,从区域构造格局出发,结合构造变动事件、主要时期盆地原始面貌等,对鄂尔多斯盆地南部中新生代盆地演化-改造过程及盆山耦合关系进行了探讨。在前人研究的基础上,结合大量的矿物年龄资料,将盆地演化划分为晚三叠世延长期、中侏罗世延安期、直罗-安定期及早白垩世4个演化时期,晚白垩世以来可划分为：晚白垩世-古新世、始新世-渐新世、中新世早中期、中新世晚期-上新世及第四纪5个改造阶段；对4个主要成盆期的原始盆地面貌进行了恢复,初步确定了盆地南部的沉积范围,认为发育鼎盛时期盆地延长期南界可达北秦岭,侏罗纪时期逐渐向北收缩,至早白垩世盆地南界仍位于今渭河盆地甚或秦岭北麓；延长期东界在冀、皖一带,侏罗纪有所收缩,直罗-安定期已西迁至太行山以西地区,而吕梁山地区大致限定了早白垩世盆地的东界；西南边界不同时期变化不大,始终位于六盘山西麓大断裂附近。盆地南部晚三叠世延长期构造背景活跃,其与南北古板块最终拼接、碰撞,秦岭造山关系密切,为中生代盆山耦合的开始,盆地南部具前陆盆地发育特征,秦岭造山带基本控制了该时期盆地南部物源,长7-长1时期盆地南北两大物源交汇于今环县-华池-黄陵一带；早中侏罗纪为坳陷盆地发育时期,盆地沉积中心向北发生明显迁移；晚侏罗世-早白垩世早期,秦岭陆内造山强烈,逆冲推覆明显,盆地西南部呈现前陆盆地结构,以磨拉石沉积建造为主；早白垩世中晚期为伸展构造背景下坳陷盆地发育时期；渭河盆地古近纪的裂陷伸展沉降-沉积与秦岭造山带的快速隆升及强烈剥蚀密切相关,这是鄂尔多斯盆地南部又一期密切而重要的盆山耦合关系,两侧山体(尤其以北秦岭为主)不仅为其提供了充足的物源,而且以断块翘倾的形式控制了渭河盆地的沉积-沉降及向外扩张,彼此相关、耦合明显。中新生代两期盆山耦合-响应的研究,既抓住了盆地后期改造和原盆恢复的实质——区域动力学背景和来源,将改造和恢复统一到该区构造动力学演化的过程之中,具有重要的科学意义和创新性。更多还原

【Abstract】 Sedimentary basin and orogen are the basic structural units. They are coexistence as a contradictory unity with opposites, because they often form and evolve in uniform structural and dynamic framework. We must reveal orogenic process from studying basin and explore the formation mechanism of the basin from studying orogen. So that we can reconstruct the relationships with basin-mountain coupling systems and dynamic transform mechanism in different periods. In this way we discuss the formation of continental orogen and sedimentary basin, geodynamic evolution mechanism and migration of substances would be more effective and in-deep.With the three principles (including integrity, development and synthesis) of basin analysis as the guidance, the research methods of reforming basin, reconstruction of the original basin boundary and coupling relationship of basin-mountain has been used. Considering regional tectonic framework, tectonic events and characteristics of prototype basin in primary period of basin evolution, the author use geological analysis, mineral dating method, provenance analysis method and restoration of eroded thickness to investigate the evolution and reforming process of southern Ordos basin in Mesozoic-Cenozoic and basin-mountain coupling relationship in two periods.Based on a large amount of mineral age data, the basin evolution was divided into four periods:Late Triassic Yanchang period, middle Jurassic Yan’an period, Zhiluo-Anding period and early Cretaceous. Since the late Cretaceous the reforming process of basin can be divided into five stages: late Cretaceous-Paleocene, Eocene-Oligocene, early and middle Miocene and late Miocene-Pliocene and Quaternary. Through reconstructing the paleo-topography of the four major forming periods, and original sedimentary basin boundaries of southern basin was initially identified, which indicated the southern boundary may extend to the North-Qinling Mountain in Yanchang period that was the peak development of Ordos basin, then it move to north gradually in Jurassic and located in Weihe basin even northern Qinling Mountain in early Cretaceous. The east boundary was in Hebei and Anhui province in Yanchang period. Then it also contracted in Jurassic and moved westward to the west of Taihang mountain area in Zhiluo-Anding period. Lvliangshan mountain roughly controlled the boundary in early Cretaceous, while the southwest boundary was always near the large faults at the western Liupan Mountain with little change in different period.In late Triassic Yanchang period which is the initial stage of basin-mountain coupling in Mesozoic, foreland basin characters developed in southern basin and had significant coupling relationship with Qinling orogen when the tectonic background is active. The Qinling orogen almost take control of the provenance of southern basin, so during Chang 7-Chang 1 member, the provenance from south and north convergence at Huanxian-Huachi-Huangling area. Early and middle Jurassic, depression basin developed and the basin moved to the north obviously. Late Jurassic-early to early Cretaceous, intracontinental orogenic movement of Qinling orogen was very strong and the thrust nappe was obvious. So the southern basin had the unique feature of intracontinental foreland basin which was mainly molasse formation. Middle and late of early Cretaceous, depression basin developed in extension tectonic setting. The development of Cenozoic Weihe fault has tight connection with the extension, uplifting and faulting of Qinling orogen in K2-E1 under the total compression system. South of Ordos basin began to couple with mountain for the second period. So bilateral mountain (northern Qinling Mountain and northern Weihe uplift) not only provide sufficient provenance but also take control of deposition and subsidence of Weihe basin and make it outward expanding in the form of warped fault. The study of two periods of basin-mountain coupling in Mesozoic-Cenozoic not only get the internal of basin post-reforming and reconstructing original sedimentary basin boundaries which are regional dynamic background and source but also use reforming and restoring methods to research evolution of structural dynamics in the study area, which has the important scientific significance and innovation.更多还原