关中盆地古近系沉积特征与古地理特征分析

发布时间：2018-06-11 19:13

本文选题：关中盆地 + 古近系　；参考：《西安石油大学》2015年硕士论文

【摘要】：关中盆地夹持于鄂尔多斯地台与秦岭造山带之间,是在燕山期隆起之上形成的伸展型断陷盆地。自中新生代以来,盆地长期处于特殊的地质构造应力场中,构造复杂,断裂发育,且长期处于不均衡沉降中,造成地层沉积厚度较大,南北分异明显,沉积环境、岩性组分变化复杂。本文运用沉积学、古地理学、构造学及石油地质学等理论,在野外地质调查及地化分析资料的基础上,深入分析已有测井、地震资料,综合前人研究成果,系统地对关中盆地古近系沉积特征、构造特征及古地理特征进行了研究。研究表明:古近系地层具有近物源的特点,分布在不同位置的充填沉积物属于多物源沉积体系:来自秦岭山前的冲积扇沉积,以粗碎屑沉积物为主,粒度累积概率曲线主要为两段式,孔隙发育,结构疏松,分选中等;来自盆地北部隆起区的地层,沉积物由河流及洪积扇组成,碎屑颗粒粒度相对较细。关中盆地沉积相特征、古地理特征及其变化规律是随着盆地的演化而发生转变的,本文以地球物理学标志为主要依据,结合岩石学标志和沉积构造标志,在区域沉积构造背景下,可将研究区古近系划分为2个主要沉积体系。古近纪初期,红河组在水动力较强、水体动荡的环境下沉积,以洪积、坡积相为主;至早渐新世,发育以河湖相沉积为主的白鹿塬组,岩性主要为灰白色块状砂岩夹棕红色泥岩;到古近纪末期,盆地发生二次隆升,形成不整合。
[Abstract]:The Guanzhong basin lies between the Ordos platform and the Qinling orogenic belt and is an extensional faulted basin formed on the Yanshanian uplift. Since the Mesozoic and Cenozoic, the basin has been in the special geological structure stress field for a long time, the structure is complex, the fault is developed, and is in the unbalanced subsidence for a long time, which results in the formation deposition thickness is large, the north-south differentiation is obvious, the sedimentary environment is obvious. The variation of lithologic composition is complex. Based on the theories of sedimentology, paleogeography, tectonics and petroleum geology, and on the basis of field geological survey and geochemical analysis data, the existing logging and seismic data are deeply analyzed, and the results of previous studies are synthesized. The sedimentary, tectonic and paleogeographic characteristics of Paleogene in Guanzhong Basin are systematically studied. The results show that Paleogene strata have the characteristics of near-provenance, and the filling sediments distributed in different positions belong to multi-source sedimentary system: alluvial fan deposits from the front of Qinling Mountains, mainly coarse clastic sediments. The cumulative probability curve of grain size is mainly two-segment, pore development, loose structure and medium separation. The sediments from the northern uplift area of the basin are composed of rivers and alluvial fans, and the grain size of clastic grains is relatively fine. The sedimentary facies, paleogeography and its variation in Guanzhong Basin change with the evolution of the basin. This paper is based on geophysical markers, combined with petrological and sedimentary structural markers. Under the background of regional sedimentary structure, Paleogene can be divided into two main sedimentary systems. In the early Paleogene, the Honghe formation was deposited in a strong hydrodynamic and turbulent water environment, mainly in the alluvial and slope facies, and in the early Oligocene, the Bailuyuan formation, which was dominated by the fluvial and lacustrine facies, was formed in the early Oligocene. The lithology is mainly grayish-white block sandstone with brown red mudstone, and by the end of Paleogene, the basin has two uplift and unconformity.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.6;P512.2

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