华北大陆楔入的华南板内效应:安徽沿江台阶式逆冲推覆构造及其控矿作用

Intracontinental Deformation of South China due to Penetration of North China: Fold and Thrust Structures and Their Ore-Controlling in Southern Anhui, South China

华南-华北大陆的碰撞和印度-亚洲大陆碰撞的形式非常相似,既发生了华南大陆向华北一侧的强烈的大陆俯冲、华北大陆向华南数百公里的楔入,又伴随有大陆块体的逃逸.中国东部中生代构造变形异常复杂,很可能与华北大陆的这种楔入存在直接的成因联系,但对华南-华北大陆碰撞和华北向华南的楔入在中国东部所产生的深刻的板内变形效应,了解不多.研究安徽南部沿江地区的逆冲推覆构造带来探讨这种大陆碰撞和楔入在华南板内的构造效应.安徽沿江推覆构造带是扬子褶皱冲断带的重要组成部分,以台阶式逆冲为其构造特色.对其构造类型进行了详细的分类,并建立了局部平衡构造剖面,计算了造山缩短量.安徽沿江推覆构造带以台阶式逆冲断层为其构造特色,这种推覆构造广泛、密集,根据平衡剖面方法计算得缩短率为55.9%.同时发现推覆构造对金属矿藏的控矿作用,这种控矿作用具有系统性和层控性等特点.

Associated with the intense northward continental subduction of the South China block, the indentation of the North China block into the South China block, and the tectonic escape of lithospheric blocks, the North_South China collision is very similar to the India_Eurasia collision. The extremely complex deformation of eastern China during the Mesozoic Era should have been related to this collision and penetration, however, we knew little about how the tectonic scenario occurred. So we chose in this paper southern Anhui in the northern Yangtze plate to shed insights into this interesting question. This paper in detail studied the styles of the thrust belt, and constructed a local balanced cross_section of deformation. The amount of the orogenic shortening was estimated to be up to 55.9%. In addition, the ore_controlling of the stepped thrust faults was discussed.