【作者】 魏明霞；

【导师】 王锋；

【作者基本信息】 长安大学 ， 构造地质学， 2009， 硕士

【摘要】 鄂尔多斯盆地西缘构造带由于所处的重要构造环境以及良好的油气和煤炭资源前景,长期以来就引起能源工作者的广泛关注。区内的汝箕沟地区是我国重要的太西煤的产地,盛产世界上少有的低灰低硫优质无烟煤。本论文在充分收集前人资料和课题研究的基础上,以构造地质学、层序地层学和沉积学为理论依据,结合现有的基础地质资料与最新测试成果和相关论文,配合地球化学分析的方法,从贺兰山汝箕沟地区中生代的地层特征,岩石特性,沉积分析及构造变形等方面的研究入手,通过典型的地质现象分析,探讨了贺兰山汝箕沟地区中生代构造环境属性。(1)通过汝箕沟地区中生代晚三叠世-早中侏罗世的地层特征,沉积分析和鄂尔多斯盆地内部进行对比、晚三叠世延长组及早侏罗世沉积物源和古水流向分析,推断出汝箕沟地区在中生代早中期是鄂尔多斯盆地的一部分,物源区主要是来自于北部的正谊关断裂;(2)通过对汝箕沟玄武岩地质地球化学指标,稀土和微量元素测试资料进行的多种判别分析,确定该玄武岩为板内拉斑玄武岩,形成于板内张性构造环境,其形成时代为晚三叠世-早中侏罗世,反映了该时期汝箕沟地区处于拉张的区域构造环境;(3)通过小松山断层面之下地层分布规律,顺层断层特征及裂变径迹测试资料,结合其变形特点,认为中生代汝箕沟地区西麓处于一个由东向西平缓抬高的斜坡环境,小松山断层是一重力滑覆断层,它代表了近东西向的拉张,目前汝箕沟地区西麓东高西低的剖面特征是该区后期构造反转的结果;(4)综合分析论证得出,汝箕沟地区在晚三叠世-早中侏罗世处于近东西向拉张应力背景下的区域构造环境,具有拉张断陷性质。更多还原

【Abstract】 Because of the western margin of ordos basin tectonic belt locates in the important tectonic setting as well as the bright prospect of its oil, gas and coal resources, it has widely aroused energy worker’s interest and attention for a long time. Rujigou area is an important area of Taixi coal producing area of our country. Taixi coal which is low ash and sulfur,while high quality anthracite is very rare in the world.This thesis is basesd on collecting the predecessor material and the researchs on this topic, taking the tectonic geology, the sequence stratigraphy and the sedimentology as the theory bases, unifing the existing foundation geological data with the newest test achievement and the related papers, and coordinating the geochemistry analysis method. It starts with formation characteristics, the rock characteristics, the deposition analysis and constructure distortion researchs,etc of the Rujigou area Mesozoic Era’s. Through the analysis of typical geological phenomenon, the author of this thesis has discussed the nature of Rujigou area mesozoic tectonic setting.(1)Through comparison between Rujigou area Mesozoic Era late Triassic period-early and middle Jurassic period formation characteristics, sedimentation analysis and that of Ordos Basin and the analysis of the late Triassic period extension and early-middle Jurassic Period deposit provenance it sets forth that during the period. Rujigou area was part of the Ordos basin and the provenance originated Zhengyiguan fault;(2)Through the analysises of the indicators of the Rujigou basalt geology geochemistry, the rare earth and the trace element test material, it is determined that this basalt for within-plate tholeiite basalt formed in within-plate extension tectonic setting in the late Triassic-middle Jurassic periods. It reflectes that this period the Rujigou area is in the extension tectonic setting;(3)According to the stratum distribution rules and characteristic of the Xiao Sungshan bedding fault, and the fission diameter mark test materials, and its distortion characteristics, the author of this thesis belives that thought that the Mesozoic Era, the western ridge of Rujigou area used to be on a slope and topography slowly declines from west to east. The Xiao Sungshan bedding fault used to be gravity slip detachment struture and it has represented the extension from the east to west. At present the Rujigou area is higher in the east and lower in the west, which is the result of the reversion of this area in later time;(4)It can be concludes that, in Mesozoic Era late Triassic period-early and middle Jurassic period, Rujigou area was in east-west region tensional stress environment which was tensional fault subsidence.更多还原