蚌埠—淮北地区电性结构及地质意义

Electrical structure of the Bengbu-Huaibei area and its geological implications

通过安徽蚌埠—淮北地区开展大地电磁剖面探测,结合重磁异常,获得了该区深部电性结构及主要地层展布和断裂性质的信息,尤其是徐宿弧形构造形态和深部含煤系地层发育情况。结果表明:①上古生界主要分布在徐宿弧形构造地表高阻推覆体之下,具有低阻、低密度的物性特征,连续性较好,认为推覆构造下煤矿勘查潜力大。②剖面上断层早期以逆断层为主,使得局部下古生界及元古宇覆于上古生界之上,后期以正断层为主,控制新生界沉积。③徐宿弧形构造海拔-4 km以浅表现为“高、低”双层电性结构,主冲断层面由F 5、F 6断裂组成;其地表高阻推覆体前缘西北至萧县,南至固镇县北,在闸河地区被广泛剥蚀。上述成果为该区基础地质研究和找矿勘查提供了重要地球物理信息。

This study conducted magnetotelluric profiling in the Bengbu-Huaibei area of Anhui Province.Combined with gravity and magnetic anomalies,it obtained the deep electrical structure,the distribution of primary strata,and the properties of faults in the area,particularly the morphology of the Xuzhou-Suzhouarcuate nappe structure and the development of deep coal-measure strata.The results indicate that:(1)The Upper Paleozoic strataare primarily distributed under the high-resistivity nappe on the surface of the Xuzhou-Suzhouarcuate nappe structure.Theymanifest low-resistivity and low-densityphysical properties and high continuity,suggesting high exploration potential for coal beneath the nappe structure;(2)On the profile,early-stage faulting was dominated by reverse faults,resulting in local Lower Paleozoic and Proterozoicstrata overlying the Upper Paleozoic strata.In the later stage,normal faults predominated,controlling the Cenozoic deposition;(3)The Xuzhou-Suzhouarcuate nappe structure exhibits a'high-low'double-layer electrical structure at burial depths shallower than 4 km,withthe dominant thrust fault plane composed of F5 and F6 faults.The leading edge of the high-resistivity nappe on the surface extends northwestward to Xiaoxian County and southward to northern Guzhen County,experiencing significant denudation in the Zhahe area.The above results provide critical geophysical information for the basic geological research and mineral exploration in the study area.