【作者】 黄凯；

【导师】 吴磊； 肖安成；

【作者基本信息】 浙江大学 ， 地质工程（专业学位）， 2018， 硕士

【摘要】 英雄岭背斜带南侧靠近祁曼塔格构造带,西侧紧邻阿尔金走滑断裂,构造位置非常关键,是研究挤压和走滑双边界条件控制下的柴达木盆地构造变形的理想地区。同时它也是现今柴达木盆地最高地形所在,高出盆地整体平均海拔近800米,其北东侧已经被强烈的风蚀。英雄岭背斜带不仅在其自身地貌形态方面非常具有独特性,还对认识柴达木盆地内部新生代变形及其传递和转换过程、理解柴达木盆地与周缘的祁曼塔格体系、阿尔金断裂系的耦合关系有着十分重要的作用,其结构和变形的研究对认识青藏高原北缘地区的变形特征和盆山耦合关系有着重要的意义。本文充分运用了二维、三维地震数据、钻井资料、野外地质调查,对柴达木盆地西部英雄岭背斜带的整体变形结构、缩短量、滑脱面深度进行了系统的定量研究,在此基础上探讨了英雄岭背斜带与祁曼塔格、阿尔金断裂系的关系,及其对青藏高原东北缘新生代变形的启示。最后本文得出如下结论:(1)英雄岭背斜带的整体变形主要受控于自南向北逆冲的两个大型基底断裂—XI号断裂和英北断裂所控制,并受下干柴沟组上段发育的膏岩层分布的影响而具有明显的东西分段特征。西段狮子沟背斜主要受浅层狮子沟断裂沿膏盐岩层的滑脱控制,深部的XI号断裂及其分支断裂对狮子沟背斜浅部的变形影响很小;干柴沟背斜和咸水泉背斜主要受基底卷入的英北断裂及其反冲断裂控制。东段油砂山背斜受深部XI号断裂与浅层的反冲断裂(油砂山断裂)组成的构造楔控制。干柴沟背斜向东趋于宽缓并逐渐消失;油泉子背斜是发育在基底卷入的英北断裂上盘的一个断层传播褶皱。英雄岭背斜带的缩短变形在西段最大,可达5.5km(缩短应变13%),向东逐渐减少至1.5km(缩短应变3.9%)。(2)结合地震剖面和野外地质调查揭示的生长地层和角度不整合面发育时间,认为英雄岭背斜带深部的XI号断裂在下干柴沟组上段沉积时就开始微弱活动,狮子沟组沉积时(<8.1Ma),包括XI号断裂和英北断裂在内的英雄岭地区构造活动开始加速,并在七个泉组沉积后(<1.5Ma)发生强烈褶皱隆升,形成现今的英雄岭背斜带。(3)英雄岭背斜带最北端的咸水泉背斜发育有5个次级背斜,平面上呈右阶雁列分布,表明控制咸水泉背斜形成的主要断裂具有一定的右旋压扭分量;同时发育四组逆冲断裂系统,第一组为北东东走向,断面北倾,具有一定的左旋走滑分量,是阿尔金断裂系的一部分,第二组为北北西走向,断面西倾,位于咸水泉背斜东侧,控制了咸水泉背斜的整体构造形态,是英北断裂的一部分并具有一定的右旋走滑分量,第三组和第四组分别为一系列北东或北北东倾的、呈雁列式排布的逆断层,是第二组断裂上盘的反冲断裂。咸水泉背斜具有明显的南北分段特征,北部的两个次级背斜轴和南部的三个次级背斜轴的走向上有约15度左右夹角,二者所控制的两翼地层产状也存在明显不一致的情况;这种南北分段特征出现的原因是,北段除了受控于北东东向的挤压冲断外,还受到阿尔金断裂系左旋走滑冲断的强烈影响,二者交汇区发生了强烈的北北西向的挤压变形。这些证据都表明阿尔金断裂确实对英雄岭背斜带产生了影响,但影响的范围有限。(4)通过英雄岭的结构分析,滑脱面深度计算,并结合前人研究构建了两条横穿祁曼塔格、柴西南和英雄岭的大剖面。三者总体构成一个由南向北逆冲的,滑脱于14-18km的脆韧转换带之上的大型陆内冲断系统。结合前人对该地区活动时间的研究发现,该冲断系统的起始活动时间也具有明显的自南向北传递的过程:祁曼塔格在晚白垩世-新生代初期就开始快速隆升,柴西南地区在路乐河组沉积时就开始活动并逐渐向北、向东传递,英雄岭地区的活动最年轻,直到8.1Ma以后才发生强烈褶皱变形,与此同时柴西南地区的活动开始减弱。这些观测表明,英雄岭背斜带是祁曼塔格冲断带的前锋,英雄岭背斜带的缩短主要是该冲断体系造成的。英雄岭背斜带新生代缩短应变具有明显的自西向东减小的趋势也表明阿尔金左旋走滑断裂系对其形成也有一定的影响。更多还原

【Abstract】 The Yingxiong Range is adjacent to Altyn Tagh Fault in northwest and the Qiman Tagh System in south side.Its critical tectonic position is ideal for understanding the structural deformation of Qaidam Basin bounded by compression and strike-slip tectonic condition.It is also the highest topography in the whole Qaidam.The average elevation above the basin is nearly 800 meters,and its northeastern part has been subjected to strong erosion of wind.Not only has unique features in topography,but also important to recognize the internal deformation and transfer process in the Qaidam Basin and understand the relationship among Qiman Tagh System,Altyn Tagh Fault,Qaidam Basin.To study structure and deformation of Yingxiong Rang is great significance for understanding the deformation characteristics and basin-mountain coupling in the northern Tibet Plateau.In this paper,we present a detailed structural analysis,shortening and detachment depth calculation based on two-dimensional seismic data,three-dimensional seismic data,well log and field investigation.We discuss the relationships between the Yingxiong Range Anticlinal Belt and the Qiman Tagh System and Altyn Tagh Fault.Finally,the conclusions are summarized as follows:(1)The deformation of Yingxiong Range Anticlinal Belt is mainly controlled by the two main basement-involved thrusts that are north-directed thrusts including XI Thrust and Yinbei Thrust.Its deformation are also affected by the distribution of gypsum layer developed in the Upper Xiaganchaigou Formation.In west part,Shizigou Anticline is mainly controlled by slipping of the Shizigou Fault along the gypsum layer in shallow but little effect by the XI Fault and its branch faults in deep.The Ganchaigou Anticline and Xianshuiquan Anticline are mainly controlled by the basement-involved Yinbei thrust and its reverse-directed fault.In the east part,Youshashan Anticline is controlled by tectonic wedge which consist of ⅩⅠ Thrust and Youshashan fault.Ganchaigou Anticline tends to be gentle and gradually disappears to the east;the Youquanzi Anticline is a fault propagation fold in the hanging wall of Yinbei Thrust.The shortening deformation of the Yingxiong Anticlinal Belt is the largest in the west part,which can reach 5.5 km(13%of the strain)and decreases gradually to 1.5 km(the strain is reduced by 3.9%).(2)Combining the development time of the unconformity and growth strata revealed by seismic profiles and field geological surveys,it is believed that the XI fault deep in the Yingxiong Anticlinal Belt began to be weakly active during the deposition of Upper Xiaganchaigou Formation and was accelerated with Yinbei Fault during the deposition of the Shizigou Formation(<8.1Ma).Subsequently,strong fold and uplift occurred,forming the current Yingxiong Range.(3)There are five secondary anticlines in the Xianshuiquan Anticline at the northernmost tip of the Yingxiong Range and a right-step en echelon distribution.It is show that the main fault which controls the fold has dextral strike-slip component.Four groups of thrust are developed,the first group which has north dip and NEE-trending has a left-lateral component and is apart of Altyn Tagh Fault system.The second group which has west dip and NNW-trending is located in eastern Xianshuiquan Anticline.The structural configuration of Xianshuiquan is controlled by the second group which is the part of the Yinbei Fault and has a certain right-lateral strike-slip component.The third and fourth groups are a series of thrust which have NE-dip or NNE-dip and arranged in an en echelon.This two groups faults are the reverse fault of the second set of faults.We divide the Xianshuiquan Anticline into the north and the south parts.The south part is little influenced by the Altyn Tagh Fault system,and characterized by the development of NNW-trending secondary anticlines and NW-trending back-thrusts with small horizontal shortening.The north part is greatly affected by the Altyn Tagh Fault system,and characterized by NWW-trending sub-anticlines and back-thrusts with much larger amount of shortening.Our results support that the Qaidam basin is a compression-dominated basin,and the influence of the sinistral strike-slip Altyn Tagh Fault system on its deformation is only confined within a limited area in the Cenozoic.(4)Through the structural analysis of Yingxiong Range,detachment calculation,and combine with previous research,we build,two large cross-sections across the Qiman Tagh,southwestern Qaidam and Yingxiong Range.They constitute a large intracontinental north-direct thrust system above the brittle-ductile transition zone of 14-18km.Combining previous studies on the activity time of this area,it was found that the initial activity time of the thrust system also has a significant transfer process from south to north.In the Late Cretaceous-Early Cenozoic era,the Qiman Tagh began to rise rapidly.The southwestern Qaidam began to active during the deposition of the Lulehe Formation and gradually transfer to north and east.The activities in the Yingxiong Range were stable until 8.1 Ma.Tectonic Activity in the southwestern Qaidam began to weaken after 8.1Ma.These observations indicate that the Yingxiong Range Anticlinal Belt is front end of the Qiman Tagh thrust belt,and the shortening of the Yingxiong Range Anticlinal Belt is mainly caused by the thrust system.Shortening of Yingxiong Range Anticlinal Belt in the Cenozoic era shows a significant decrease from west to east.It also shows that the Altyn Tagh Fault system also has some influence on its formation.更多还原