帕米尔东北缘山前冲断带时空差异及其机制

发布时间：2018-07-09 21:29

本文选题：齐姆根 + 冲断带　；参考：《浙江大学》2015年硕士论文

【摘要】：相对于认识较为统一的帕米尔西缘径向逆冲模型,东缘的形成演化模型存在较多争议(Strecker et al.,1995; Cowgill,2010;李康,2014)。Cowgill (2010)提出了帕米尔东北缘的走滑模型,并认为喀什-叶城走滑转换系统开始于。-25Ma; Sobel et al.(2011)提出该走滑转换系统在～5Ma以来活动减弱。李康(2014)在走滑模型的基础上提出了撕裂断层模型,认为存在垂直于喀什-叶城走滑转换系统的北东向撕裂断层,并认为它们是造成帕米尔东北缘冲断带变形时空差异的主要原因。帕米尔东北缘冲断带的时空差异性前人做了大量研究(曲国胜等,1998；肖安成等,2000；沈军等,2001；胡建中等,2008；陈汉林等,2009; Cowgill,2010;程晓敢等,2011)。但在变形样式、变形时间、演化过程等方面还存在不同认识。另外,山前冲断带晚于5Ma以来的变形起始时间(伍秀芳等,2004；程晓敢等,2012),与造山带内部大量的热年代学数据揭示的大于20-25Ma的隆升剥露事件(Amaud,1993; Sobel and Dumitru,1997; Sobel et al.,2011)存在明显的差异,前者在山前形成了巨厚的前缘坳陷。塔西南盆地最初的负载挠曲接受沉积的时间是什么时候还一直没有得到解决。本文利用地表地质调查、钻井资料、地震解释成果,通过构造解析、生长地层分析和平衡剖面恢复等手段,对帕米尔东北缘冲断带的齐姆根及邻区的构造变形样式、变形时间和变形强度等进行了研究,分析了时空差异特征及其形成机制,恢复了形成演化过程。得出了如下几点结论：1.齐姆根地区新发现乌恰群沉积时期前渊的存在,敲定了塔西南盆地最初负载挠曲接受沉积的时间为中新世早期,该时间和热年代学的结论相呼应,而在两侧构造带没找到该期前渊存在的证据。此外,齐姆根构造带阿图什组沉积时期前渊更靠近盆地,证明前渊不断向前陆方向迁移。2.变形时间上：两侧构造带起始活动时间早(上新世中、晚期),中间齐姆根构造带起始活动时间晚(更新世早期)。3.变形强度上：齐姆根构造带缩短量(20km)和缩短率(21%)明显小于西侧苏盖特构造带的46km和30.5%,以及东侧柯东构造带普西段的64.2km和29.5%。4.提出了帕米尔东北缘冲断带变形时空差异的机制及形成演化过程：中新世早期帕米尔-西昆仑山的隆升在塔西南山前形成了一个统一的前渊。上新世以来,齐姆根构造带变形强度明显弱于两侧,另外,齐姆根构造带东、西侧的伊利亚斯沟右行走滑断层和同由路克左行走滑断层的发育使得齐姆根构造带整体向北凸出,保留了中新世形成的前渊而两侧构造带强烈的冲断抬升将中新世形成的前渊剥蚀、破坏。
[Abstract]:Compared with the unifying radial thrust model of Pamir's western margin, the formation and evolution model of the eastern margin is controversial (Strecker et al. 1995; Cowgill 2010; Li Kangwei 2014). Cowgill (2010) proposed a strike-slip model for the northeastern margin of Pamir. It is considered that the Kash-Yecheng strike-slip conversion system began from .-25 Ma; Sobel et al. (2011) and suggested that the activity of the strike-slip conversion system has weakened since 5 Ma. Li Kang (2014) proposed a tear fault model based on the strike-slip model. It is considered that there exists a north-east tearing fault perpendicular to the Kash-Yecheng strike-slip conversion system. It is considered that they are the main reasons for the temporal and spatial difference of deformation in the thrust zone of the northeastern margin of Pamir. The temporal and spatial differences of the thrust belt in the northeastern margin of Pamirs have been studied by previous scholars (qu Guosheng et al. 1998; Xiao Ancheng et al. 2000; Shen Jun et al. 2001; Hu Jianzhong et al. 2008; Chen Hanlin et al. 2009; Cowgillilln 2010; Cheng Xiao dang et al. 2011). However, there are still different views on deformation style, deformation time, evolution process and so on. In addition, the deformation initiation time of the Foreland thrust belt later than 5 Ma (Wu Xiufang et al. 2004; Cheng Xiaogang et al. 2012) is significantly different from the uplift and denudation events (Amaudine 1993; Sobel and Dumitruan 1997; Sobel et al.2011) revealed by a large number of thermochronological data in the orogenic belt. The former formed a very thick front depression at the front of the mountain. The time when the initial load deflection was accepted for deposition in the southwest Tarim Basin has not been resolved. By means of surface geological survey, drilling data, seismic interpretation results, structural analysis, growth stratigraphic analysis and balanced section restoration, the structural deformation patterns of Zimgen and its adjacent areas in the thrust belt of the northeastern margin of Pamir are studied in this paper. The time and intensity of deformation are studied, the characteristics of space-time difference and its formation mechanism are analyzed, and the process of formation and evolution is restored. The following conclusions were drawn: 1. In the Qimegan area, the existence of the foredeep of the Wuqia Group during the sedimentary period was newly discovered, and it was determined that the initial loading flexural acceptance time of the southwest Tarim Basin was the early Miocene, which coincided with the conclusion of thermochronology. However, no evidence of the existence of the foredeep was found in the two sides of the tectonic belt. In addition, the Artushi formation in the Qimegen tectonic belt is closer to the basin during the sedimentary period, which proves that the foredeep moves continuously in the forward continental direction. The deformation time of the two tectonic belts is early (middle and late Pliocene), and that of the middle Qimegan tectonic belt is late (early Pleistocene) .3. In terms of deformation strength, the shortening amount (20km) and shortening rate (21%) of the Qimegan tectonic belt are obviously smaller than those of the 46km and 30.5 branch of the west Sugaite tectonic belt, and the 64.2km and 29.5.4 of the Puxi section of the eastern Kedong structural belt. The mechanism of temporal and spatial difference of deformation in thrust belt of northeastern Pamir and its evolution process are put forward: the uplift of Pamir-West Kunlun Mountains in the early Miocene formed a unified fore-deep in front of the South Taxi Mountains. Since the Pliocene, the deformation intensity of the Qimegen tectonic belt has been obviously weaker than that of both sides. In addition, the development of the Ilyas trench right strike-slip fault in the east and west of the Zimgen tectonic belt and the synchronic Luke left strike-slip fault make the Zimegan tectonic belt protrude northward. The foredeep formed in Miocene is preserved and the strong thrust uplift on both sides of the tectonic belt will denude and destroy the foredeep formed in Miocene.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P548

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