鄂尔多斯盆地东缘中—新生代构造—热演化研究

发布时间：2018-09-18 13:07

【摘要】：鄂尔多斯盆地东缘是我国重要的煤层气产地,对该区域的盆山构造以及隆升剥露历史的基础地质研究对于煤层气的勘探开发具有重要而深远的意义。本论文主要通过野外地质调查、室内地震解释以及磷灰石裂变径迹热年代学揭示研究区域中-新生代构造-热演化历史。通过对鄂尔多斯盆地东缘地区野外褶皱、断层构造特征研究以及对延长南工区地震剖面进行初步解释,结果显示:鄂尔多斯盆地东缘构造较为简单,主要与印支运动、燕山运动和喜山运动密切相关。出露地层产状平缓向西倾斜,其角度为2°～3°之间。露头断层以正断层为主,其断距一般为1～2m之间,断层破碎带不发育。褶皱类型为宽缓褶皱,其走向一般为NE、NNE。延长南地震资料显示地层平缓西倾,可见中部破碎带、西部断鼻带和东部缓坡带。通过对吕梁山山体样品与盆地内样品进行磷灰石裂变径迹热年代学测试,研究鄂尔多斯盆地东缘吕梁山山体及盆地的构造-热演化过程,对于探讨和认识华北克拉通演化和破坏等科学问题有重要意义。测试表明,山体磷灰石年龄分布于138Ma～48Ma,其横切剖面图中裂变径迹年龄与山谷走势基本一致,通过对样品年龄-高程拟合得到山体隆升速率为7.35m/Ma,拟合度达到0.7。同时围限径迹长度与样品海拔高度呈负相关关系。盆地碎屑磷灰石样品经年龄为50Ma～39Ma。样品年龄-高程拟合得到盆地隆升速率为12.2m/Ma,拟合度达到0.99。对盆山样品进行热史模拟发现,从早侏罗世—早白垩世到始新世,山体样品缓慢抬升冷却,之后加速抬升脱离部分退火带,盆地样品在晚白垩世进入部分退火带后,于始新世开始加速抬升冷却,中新世脱离部分退火带。通过对吕梁山山前新近系地层古地磁、以及沉积相分析,发现在上新世盆山耦合进一步发育,吕梁山伸展成山,其东部汾渭地堑下陷接受沉积。
[Abstract]:The eastern margin of Ordos Basin is an important producer of coalbed methane in China. The basic geological research on basin-mountain structure and uplift and exfoliation history in this area is of great and far-reaching significance for the exploration and development of coalbed methane. In this paper, the history of Meso-Cenozoic tectonic-thermal evolution is revealed through field geological survey, indoor seismic interpretation and pyrochronology of apatite fission track. Based on the study of the characteristics of field folds and faults in the eastern margin of Ordos Basin and the preliminary interpretation of the seismic profile of Yanchang South work area, the results show that the eastern margin of the Ordos Basin is relatively simple, mainly associated with the Indosinian movement, The Yanshan movement is closely related to the Himalayan movement. The outburst formation is inclined to the west with an angle between 2 掳and 3 掳. The outcrop fault is dominated by normal fault, and its fault distance is generally between 1m and 2m, and the fracture zone is not developed. The type of fold is wide and gentle, and its trend is generally NE,NNE.. The seismic data of Yanchang South show a gentle westward dip of the strata. The fracture zone in the middle, the fault nose belt in the west and the gentle slope belt in the east can be seen. The tectonic-thermal evolution process of the Luliangshan mountain body and its basin on the eastern margin of Ordos basin is studied by means of the thermal chronological test of apatite fission track in the Liliangshan mountain body and the basin. It is of great significance to discuss and understand the evolution and destruction of North China Craton. The results show that the age distribution of apatite in mountain body is 138Ma-48Ma.The age of fission track in crosscutting section is basically consistent with the trend of valley, and the uplift rate of mountain body is 7.35m / Ma, and the fitting degree is 0.7by fitting the sample age and height. At the same time, there was a negative correlation between the length of the confining track and the altitude of the sample. The age of detrital apatite samples in the basin is 50 Ma-39 Ma. Age-height fitting showed that the uplift rate of the basin was 12.2 m / Ma, and the fitting degree was 0.99m / Ma. From the early Jurassic to the early Cretaceous to the Eocene, the mountain samples slowly uplift and cool, then accelerate the uplift and detach from part of the annealing zone, and the basin samples enter part of the annealing zone in the late Cretaceous. During the Eocene, the uplift and cooling began to accelerate, and the Miocene separated from the partial annealing zone. Based on paleomagnetism and sedimentary facies analysis of Neogene strata in front of Luliangshan, it is found that in the Pliocene basin-mountain coupling further developed, Luliangshan extends into a mountain, and the eastern Fenwei subsidence accepts sedimentation.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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