【作者】 李振华；

【导师】 陈刚；

【作者基本信息】 西北大学 ， 固体地球物理， 2011， 硕士

【摘要】 准噶尔盆地的构造热演化史是准噶尔盆地构造动力学演化研究和油气勘探备受关注的热点问题,但有关盆地北部燕山期构造事件及其古地温场特征尚存在很多争议。本文以准噶尔盆地北部地区为研究对象,在区域地质构造和“不整合”构造事件分析的基础上,重点运用构造热年代学、磷灰石裂变径迹(AFT)热史模拟与镜质体反射率(Ro)等相结合的研究方法,探讨分析了准噶尔盆地北部燕山期构造事件的峰值年龄分布特征和燕山中期构造热事件的古地温场状况。(1)通过区域地质构造和沉积建造分析,将准噶尔盆地北部的沉积盖层构造层系划分为海西期、印支期、燕山期和喜山期等四个构造层组及其相应的等9个构造层,并重点对燕山期构造层组中三个构造层的沉积建造特征进行了总结对比,认为燕山中期的石树沟群构造层具有相对活动的沉积建造组成。(2)通过野外露头剖面和地震剖面的解释对比及其燕山期“不整合”事件的时空分布特征分析,认为准噶尔盆地北部燕山期的地层不整合关系主要表现为中侏罗统西山窑组与头屯河组或下白垩统吐谷鲁群之间的角度不整合关系,表明该区在燕山中期的晚侏罗世经历了较为显著的构造变形不整合事件。(3)通过下白垩统碎屑岩锆石U-Pb定年及其年龄谱分析,获得了中生代170Ma±和140Ma±的两组锆石U-Pb峰值年龄,表明准噶尔盆地北部物源区很可能存在燕山期尤其是以140Ma±优势峰值年龄为代表的燕山中期岩浆活动,暗示盆地北部区域在这一时期具有显著的构造热液活动背景。(4)锆石和磷灰石裂变径迹(FT)分析及其FT年龄统计分布特征表明,准噶尔盆地北部区域存在160Ma、130Ma和90Ma三组FT峰值年龄,大致对应于中上侏罗统石树沟群底部、顶部和下白垩统顶部的三个构造不整合界面,指示盆地北部燕山期的多期次构造隆升变形作用主要发生在燕山中期的160-90Ma。(5)通过对中生界砂岩样品的AFT热史模拟、流体包裹体(FI)测温和泥(煤)岩Ro分析,认为研究区存在晚侏罗一早白垩世的燕山中期构造热事件,恢复其古地温梯度主要分布在3.5-4.0℃/100m,平均接近3.7℃/100m,显示出较高的古地温场特征。更多还原

【Abstract】 The tectonic thermal evolution history of northern margin of junggar basin is always a hot field in the research of the oil and gas exploration, but there are many controversies about tectonic event and palaeo-geothermal feature. The northern region in junggar basin where the tectonic event is relatively week is resaerched. Based on regional geologic structure and unconformity tectonic events, by using methods of tectonic thermal chronology analysis, thermal history modeling and vitrinite reflectance (Ro), the peak age distribution of the tectonic thermal events and palaeogeothermal field characteristics in the middle of Yanshanian is analyzed.(1) By analysis regional geological structure and sedimentary built, the layer tectonic sequence is divided into four periods of Hercynian, Indosinian, Yanshanian and Himalayan, and corresponding nine sublayer. By comparative analysis characteristic of three tectonic sublayer of Yanshanian, the Shishugou formation of Yanshanian has relative activities tectonic sedimentary build composition.(2) Through the field of outcrop, seismic profiles and unconformity tectonic events distribute in the middle of Yanshanian, we introduced the tectonic event characteristics of Yanshanian in Junggar Basin. It shows that the late Jurassic in the middle of Yanshanian experienced significant structural deformation unconformity events.(3) Through the zircon U-Pb dating and its spectrum analysis,we abtained the170 Ma±and 140 Ma±peak age, it shows there were existed a magma activity in the middle of Yanshanian,it implies in the northern of Junggar Basin in this period has a significant structural hydrothermal activity background.(4) zircon and apatite fission track (FT) analysis and its statistical distribution characteristics shows the tectonic thermal events in the middle of Yanshanian happens in 160Ma,130Ma and 90Ma. It also shows that the tectonic uplift deformation function in Junggar Basin mainly happened in the middle of Yanshanian in 160-90Ma. (5) Through the sandstone samples of Mesozoic AFT thermal history simulation and fluid inclusions (Fl) and Vitrinite reflectance (Ro) analysis, thinks research area exists tectonic thermal events in late Jurassic and the early cretaceous of the middle Yanshanian, the ancient geothermal gradient is mainly distributed in the 3.5 to 4.0℃/100m, average closer to 3.7℃/100m, shows high ancient geothermal field characteristic.更多还原