准噶尔盆地断拗转换期剥蚀厚度及其分布规律

准噶尔盆地为我国重要的陆上含油气盆地, 对其进行地层剥蚀厚度恢复能够有效地研究盆地演化历史以及油气资源评价.通过分析声波时差法的方法原理及其适用条件, 认为此方法适用于恢复准噶尔盆地断拗转换期剥蚀地层的厚度.实际计算结果表明: 断拗转换期上、中二叠统之间为主不整合, 剥蚀厚度大; 三叠系与二叠系之间形成次级不整合, 盆地剥蚀厚度相对较大, 区域位于西部盆缘地带, 自北西向南东剥蚀量逐步降低, 至盆地中心剥蚀量最低.各构造单元中, 凸起相比于凹陷所遭受的剥蚀程度较大, 反映古地貌呈现盆地西北缘高、腹部低的地形特征, 同时反映准噶尔盆地断拗转换期二叠纪晚期至三叠纪早期改造具西强东弱、边缘强内部弱的特点.

DENUDATION THICKNESS AND DISTRIBUTION RULE IN THE FAULT-DEPRESSION TRANSITION PERIOD OF JUNGGAR BASIN

The Junggar Basin is an important onshore petroleum-bearing basin in China, and the restoration of its strata denudation thickness is effective to study the evolutionary history and evaluate the oil-gas resources. By analyzing the principle and application conditions of interval transit time method, it is considered that the method is suitable for restoring the strata denudation thickness in the fault-depression transition period of Junggar Basin. The actual calculation results show that in the fault-depression transition period, there is a major unconformity between the Upper and Middle Permian with large denudation thickness, and a secondary unconformity between the Triassic and Permian, with relatively large basin denudation thickness, located in the western basin margin zone, with the denudation gradually decreasing from northwest to southeast and reaching the lowest level at the center of basin. Among the tectonic units, the convex suffered more denudation than the sag, reflecting that the ancient landform is high in the northwestern margin and low in the central basin, and the reformation of the basin is intense in the west and weak in the east, and intense in the margin and weak in the interior during the Late Permian-Early Triassic in Junggar Basin.