定远凹陷形成的区域构造背景及其演化过程

定远凹陷上古生界构造归属及其构造演化过程，对下一步该地区煤炭资源评价与非常规天然气选区具有关键性的意义。文章利用最新的地球物理与钻探成果，应用构造解析及区域对比等方法，结合区域构造规律与前人相关认识，对定远凹陷构造特征、上古生界构造归属及中生代以来的构造演化过程进行了详细的论述，其结果认为定远凹陷内发育的上古生界煤系地层属于淮南煤田中部复式向斜构造带东部的延伸。该凹陷受大别造山带隆起及郯庐断裂带中、新生代走滑活动影响，分别经历了印支期（T3）前陆变形、早中侏罗世（J1+2）相对隆起、晚侏罗世（J3）末期至早白垩世初期（K1初期）郯庐断裂带左行走滑改造、早白垩世期间（K1）至古近纪(E）伸展改造、古近纪末期挤压反转以及新近纪（Q）—第四纪（N）坳陷式均匀沉降六个主要演化阶段。

Regional Background and Tectonic Evolution of Dingyuan Sag

Tectonic evolution and its origin of the upper Paleozoic in the Dingyuan Sag are essential for the evaluation of coal resources and exploration targets of unconventional natural gas. Based on the latest geophysical and drilling data, combined with results from previous studies, we discussed the tectonic evolution and its origin in detail via structural analysis and regional comparison. Results show that the upper Paleozoic coal-bearing strata are comparable to the middle segment of the Huainan coalfield, which show an anticline pattern. The Dingyuan Sag has been affected by the strike-slip activities of the Tan-Lu Fault Zone and uplift of the Dabie Orogenic Belt from the Mesozoic to Cenozoic. The tectonic evolution in the Dingyuan Sag can be divided into six main stages, including foreland deformation in the Indosinian (T3), relative uplift in the early-middle Jurassic (J1+2), reformation by strike-slip activities of the Tan-Lu fault zone from the late Jurassic (J3) to early Cretaceous, reformation by extension activity from the early Cretaceous (K1) to Paleogene (E), inversion by compression activity in the late Paleogene, and depression with uniform deposition from the Neogene to Quaternary (N-Q).