【作者】 闫亭廷；

【导师】 邵铁全；

【作者基本信息】 长安大学 ， 构造地质学， 2011， 硕士

【摘要】 本文以柴北缘沙柳泉地区岩浆岩体为研究对象,利用岩浆岩演化序列的观点,对研究区建立三个岩浆带五个岩浆岩演化序列,从地理上由北向南依次为：伊克陶力岩浆带,包括呼吉日特闪长—花岗岩序列、呼吉日特辉长岩序列；沙柳泉岩浆带,包括阿母内可序列、诺日哈序列；毛牛山岩浆带包括喇嘛陶勒盖序列。笔者对研究区系统的展开了岩石学、岩石化学、稀土微量元素地球化学以及同位素年代学研究,并在此研究基础上判断出各侵入体的成岩环境,从而推断判别当时地质时期的构造环境,为柴北缘构造演化提供有利佐证。本次研究区是一个构造岩浆活动比较强烈的地区,岩浆活动始于元古宙,止于中生代。尤其以新元古代、加里东期岩浆活动较发育。基性岩浆侵入活动主要发生在新太古代,中酸性岩浆侵入活动主要发生在志留纪和二叠纪。研究区断裂构造发育,从区域上看,以呼德生大断裂为界,该断裂以北属于柯柯赛隆起,以南属于乌兰断陷盆地,是下元古界与中元古界的分界断裂,该断裂同时还控制着印支期与燕山期中酸性岩体的侵位。伊克陶力岩浆带,两个序列侵入下元古界达肯达坂岩群。通过常量元素分析,两个序列属于拉班系列；结合微量元素的分析及稀土配分模式图的特征,呼吉日特辉长岩序列为幔源成因；呼吉日特闪长—花岗岩序列为壳源成因。根据前人资料记载,该组侵入岩侵位时间为新元古代,结合构造判别图分析,该序列元古宙地质构造环境为活动大陆边缘环境。沙柳泉岩浆带,两个序列侵入于中元古界长城系小庙岩群。从主要元素分析看,两个序列铝饱和度A/CNK大于1.1,属于过铝质的钙碱性系列。通过微量元素的分析,并且结合稀土配分模式图,与壳源成因的花岗岩具有一定的相似性。通过锆石U-Pb测试该序列岩体地质年龄分别为415Ma和418Ma,结合构造判别图分析,该序列志留纪地质构造环境由活动大陆边缘转向造山阶段,产生了柯柯赛隆起。毛牛山岩浆带,喇嘛陶勒盖序列侵入中生代泥盆系火山岩段。通过常量元素分析,该序列岩石属于碱性系列的,结合稀土配分模式图,该图右倾较陡,特征与壳源成因具有相似性,说明该序列岩石来源为上地壳。通过锆石U-Pb测年,测得该序列岩体地质年龄209Ma,结合构造判别图分析,该序列二叠纪地质构造环境为内陆盆地发展阶段,产生了乌兰断陷盆地。根据以上分析,研究区在元古代—中生代经历了断裂以北挤压抬升隆起,以南拉伸断陷的过程。研究区断裂构造构造发育,对该区演化过程起着明显的指示作用。研究区主构造线方向为北西—南东。地层应受到北东南西向挤压应力,呼德生沟以北,在志留纪产生隆起。长城系地层受北东南西方向挤压,形成一系列逆断层；后期,继续受北东—南西方向挤压应力,断裂南北均产生北东向走滑断层；二叠纪,毛牛山地区受到拉张应力的作用并发展为断陷盆地。更多还原

【Abstract】 In this paper, the author use the views of magmatic evolution sequence in the study area to establish the evolution of five magmatic series from three Magmatic belt according to magmatic rocks as the research object in Shaliuquan,Qinghai Province. The sequence from north to south were called Yiketaoli Magmatic belt include Hujirite Gabbro Sequence, Hujirite Granodiorite Sequence; Shaliuquan Magmatic belt include Amuneike Sequence, Nuoriha Sequence; Maoniushan Magmatic belt include Lama Tolgoi sequence. The author systematically analysis the study area by some effective methods which is called petrology, petrochemistry, earth rare-trace element geochemistry and isotope geochronology, and determine the diagenetic environment of the intrusions on the basis of this study, and concluded the tectonic environment at that geological time to provide the evidence for the tectonic evolution of North Qaidam basin.The study area is a relatively strong magmatic activities area, the magmatic activities was began in the Proterozoic and beyond the Mesozoic. Particularly in the Neoproterozoic and Hercynian,magmatic activity was over development. basic-ultrabasic rock emplacement occurred in Neoarchean and Acidic magma emplacemen occurred in the Early Permian and Late Triassic. Faults was strongly developed in the study area. On the whole,the large faults called Hudesheng is the boundary, the north of the fault is the upheaval called Kekesai and the south belongs to Ulan basin,The large faults is samely the Boundary of the Lower Proterozoic and Proterozoic, and also controls the Triassic and Mesozoic intermediate-felsic intrusion.Magmatic belt called Yiketaoli, the two Sequence invade within the Changcheng rock group in Proterozoic. According to the main elements of analysis, the sequence are Tholeiitic series. According to the analysis of rare earth trace elements and REE patterns characteristic graph, the Sequence Hujirite Gabbro Sequence is the Mantle origin; Hujirite Granodiorite Sequence is the Crust origin;According to the tectonic discrimination diagrams analysis, in Proterozoic, the sequence of geological environment is Active continental margin.Magmatic belt called Shaliuquan, the two Sequence invade within the Changcheng rock group in Proterozoic. According to the main elements of analysis, the sequence which Al saturation(A/CNK)> 1.1, are peraluminous. According to the analysis of rare earth trace elements and REE patterns characteristic graph, f the granite of the Sequence has a certain similarity with the crust granite. By U-Pb zircon test, the emplacedl age of the rock of the sequence is about 415-418 Ma.According to the tectonic discrimination diagrams analysis, the sequence of geological environment is from Active continental margin into Orogenic stage which produced Kekesai Uplift in Silurian.Magmatic belt called Maoniushan, the Sequence called Lama Tolgoi invade within Devonian of the Mesozoic rocks group. According to major element analysis, the Igneous are sub-alkaline series. According to the analysis of REE patterns characteristic graph, the graph performance the right tilt characteristics which are similar to the crust and indicate that source of the sequence rocks is the crust. By U-Pb zircon dating, the measured geological age of the rock of sequence is about 209 Ma. According to the tectonic discrimination diagrams analysis, the sequence of geological environment is the Stage of development of inland basin which produced Wulan Rift basin.Based on the above analysis, the study area experienced the process of which the north of the Hudesheng Fracture is a compression uplift and the south is extensional rift in the Proterozoic- Mesozoic. Structural faults is strong development in the study area,and the structral faults is play a significant role in the evolution of the area. The main direction of the tectonic line in the study area is the North West-South East. The stratum should be force the NE-SW compressive stress and occur uplift in the north of Hudesheng fault. Samely,the stratum of the Wall strata is produced a series Reverse faults bacause of the the NE-SW compressive stress.Later,the south and north of the large faults is produced a series Strike-slip fault continue by the the NE-SW compressive stress. Finally, the area called Maoniushan is developed the rift basin bacause of the pulling tension.更多还原