【作者】 李月；

【导师】 周瑶琪；

【作者基本信息】 中国石油大学 ， 地质资源与地质工程， 2008， 博士

【摘要】 松潘-阿坝和龙门山地区在大地构造背景上属于扬子板块的范畴,地质研究工作和油气勘探程度较低,特别是对本区的构造样式、构造动力学以及构造演化史等问题的认识上还不清楚,影响了该区的油气勘探进程。本论文以构造地质学为理论指导,综合运用露头资料、火成岩测试、褶皱和劈理的极射赤平投影分析以及深部地球物理资料对松潘-阿坝及龙门山地区的构造样式、变质作用与构造动力学等方面进行了深入研究,结合前面的分析以及几条主要断裂的发育特征恢复了松潘-阿坝及龙门山地区的构造演化史,进而建立了龙门山地区的构造演化模式,并结合红参1井的资料分析了构造运动对研究区油气的影响。在区域地质调查基础上,论文重点讨论了龙门山造山带的构造样式,松潘-阿坝及龙门山地区的深部构造特征、动力学背景和构造演化过程。不论龙门山前山带或后山带,发育其间的主要构造形迹皆为走向北东的褶皱,特别是雁列式褶皱,以及与褶轴平行的冲断层、片理带等最为明显,此外,还伴生着一些横切或斜切褶轴走向的张性或扭性断层。研究区逆冲推覆、叠瓦冲断以及滑脱等构造样式广泛发育,并且由于研究区经历了多期构造运动的影响,因此构造样式不单单受一种因素的影响,而是多种构造因素相互叠加的结果。飞来峰作为龙门山造山带一大特色就是推覆和滑覆共同作用的结果。通过对研究区变质变形分析以及火成岩测试分析的结果表明研究区的变质作用方式主要以变形和压碎作用为主,并且伴随有变质分异作用、重结晶作用以及交代作用。龙门山地区自震旦纪以来,岩浆活动频繁,但形成的火成岩差异较大,震旦纪以酸性岩浆活动为主,古生代和早、中三叠世以基性岩浆活动为主,晚三叠世以后又转为酸性岩浆活动为主。研究区应力场在不同时期存在较大的差异,印支期主要表现为南北向挤压,燕山期以南北扭张应力场为主,而喜马拉雅期由于受到青藏高原的挤压作用的影响,而表现为东西向挤压。通过对研究区褶皱及片理的极射赤平投影分析发现,片理的形成主要是受到印支期南北方向挤压应力的作用,燕山期的剪切以及喜马拉雅期东西方向的挤压力对它的影响很小。褶皱的形成显然是经历了印支期南北方向的挤压应力和喜马拉雅期东西方向挤压应力的共同作用。松潘-阿坝地区的演化历史可以划分为四个演化阶段,即晋宁期泛扬子大陆形成阶段,加里东期泛扬子板块解体,出现裂谷、台地和古陆并列演化的局面,海西期稳定演化,中晚二叠世之交的东吴运动使得龙门山与扬子板块彻底裂解,印支期至喜马拉雅期是全面造山阶段。在此大地构造背景之上,龙门山自印支期开始了自己独特的造山过程,经历了印支期的逆冲推覆、燕山期的伸展以及喜马拉雅期的再次挤压最终定型成为现今的构造格局。松潘-阿坝地区是一油气勘探新区,成岩演化程度较高,目前还未发现有价值的油气资源。现有的资料表明研究区内主要发育一套下古生界生油、上古生界储油、三叠系为盖层的生储盖组合。红参1井所揭示的构造特征表明中、上三叠统地层发生了较明显的褶皱,印支运动使得松潘-甘孜褶皱带全面隆起成山造成了地层的强烈增厚,并且,多期次构造运动使该区的地质构造复杂化,这对该区的油气勘探带来了不利的影响。更多还原

【Abstract】 Songpan-Aba and Longmen mountain belong to plate Yangtze in tectonic setting, the degree of study to geology and exploration is very low. There aren’t clear cognation to the structure styles, tectonic dynamics and structural evolvement progress. So in this paper, guided by tectonic geology, the structure styles, metamorphism and tectonic dynamics had been studied in deep by integrating outcrop, volcanic testing data, analysis for stereographic projection of folds and cleavage and seismic data. The structural evolvement progress had been come back through all the studying had been made and the developing character of main faults, then built the structural evolvement pattern of Longmen mountain.Based on regional geological survey, I emphatically discussed the structural styles of Longmen mountain, deep-seated structure characteristics, dynamic setting and structural evolvement of Songpan-Aba and Longmen mountain. The extending direction of folds in Longmen mountain is northeast, and it is more distinct that the echelon fold, thrust fault and cleavage. There are many pulling and clipping fault, which are vertical or oblique faul. There are many thrust-nappe, imbricated clipping fault and décollement structure in the zone. Because there are many tectonic movement, the tectonic style is not involved on only on factor, but it is the result of many tectonic movements. For example, the clipping was formed by thrust nappe and slip.After analyzing the metamorphism and volcanic testing data, we found that the main metamorphism was deform and crushing, at the same time appeared with metamorphic differentiation, Recrystallization and metasomatism. After Sinian Period, the magmatic activities are frequent, and the magmatic rocks are different, the magma which is active in Sinian Period was felsic, the magma which is active in Pz and T1+2 was mafic, the magma which is active after T3 was felsic again. The stress of the zone is different at different period, the stress in Yinzhi period was extruding from south to north, in Yanshan period was pulling from south to north, and in Himalaya period was extruding from west to east. After the analysis for stereographic projection of folds and cleavage in the zone, we found that cleavage was formed by the stress from south to north in Yinzhi period, and the folds were formed by the stress form south to north in Yinzhi and the stress from east to west in Himalaya period.The evolvement processes were divided four phases which are uniform Yangtze continent on Jinning period, uniform Yangtze disaggregation on Jialidong period, stable evolvement on Haixi period and complete cracking through the Dongwu movement, mountain forming from Yinzhi to Himalaya period. The unique orogenic processes of Longmen mountain began on this tectonic setting.Songpan-Aba is a new exploration area. The degree of diagenetic evolution is high and there aren’t valuable petroleum resources found. I think lower Paleozoic as source rocks, upper Paleozoic as reservoir and Triassic as cap according to the existed data. The structural characteristics revealed by the data of well Hongcan-1 made clear that the middle-upper formation had been folded and the Triassic was one of the main structural detachment layers. Songpan-Ganzi folded belt has been uplifted during Yinzhi period, and the strata incrassated. It is very difficult to explore the petroleum because of the many tectonic movements.更多还原