秦岭造山带勉略缝合带构造变形与造山过程

秦岭晚古生代以来造山过程中的构造变形研究对建立华北板块与华南板块之间的最终拼合过程尤为重要。为此，选择勉略带进行了详细的野外调查，对其物质组成，几何学结构，变形序列，运动学和动力学作了系统解剖，认为：勉略带是有一定宽度，由一定实体组成的蛇构造混杂岩带，它包括不同时代，不同构造背景，不同起源的一系列构造岩片，如：基底岩片组，洋壳岩片组，岛弧岩片组，碰撞构造沉积楔形体，大陆边缘岩片组，它们被一系列的北倾南冲的断裂分割。勉略带到－高川段的北倾南冲逆冲断裂和勉略带北部南倾北冲的逆冲断裂组合成为现今不对称的正花状几何学结构，但勉略带的北界状元碑断裂和南界 到－略阳断裂走滑特征明显。结合勉略带邻区的构造特征，分别对带内重要断裂及岩片的构造解析表明，除主造山的大地构造演化阶段外，可将勉略带构造变形序列及演化历程总体归纳为三大阶段：俯冲变形阶段，主造山碰撞变形阶段的陆内造山调整变形阶段，并对不同变表阶段的时限，变形特征，运动学和动力学分别作了描述；最后针对该区复杂的楔入，挤出（逃逸）走滑，逆冲过程，提出了一个统一的动力学演化模式。

Deformation and Orogeny of the Mian-Lue Suture Zone in the Qinling Orogenic Belt

Deformation in the orgenesis of the Qinling orogen since the Late Palaeozoic is very important to recon-structing the last assembly process of the North China Plate and South China Plate. To understand this pro-cess, the Mian-Lue suture zone is selected to study the rock assemblages, geometry, deformational sequence, kinematics and dynamics. By synthetic analysis, the main conclusions can be summarized as follows. The Mi-an-Lue suture zone has an ophiolitic melange composed of a series of tectonic slabs of different ages, tectonic settings and origins, such as the basement slab group, oceanic crust slab group, island-arc slab group, accre-tionary sediment wedge slab, and continental margin slab group. These slabs are separated by a series of north-dipping, south-thrusting faults. The current geometry of the suture zone from Kangxian to Gaochuan appears to be an asymmetric, positive flower-shaped architecture consisting of north-dipping, south-thrusting faults in the zone and south-dipping, north-thrusting faults on the north of the zone. However, strike-slipping happened evidently in the Zhuangyuanbei fault and the Kangxian-Lueyang fault, regarded as the northern boundary and the southern boundary of the Mian-lue suture zone respectively. Based on structural analysis of the major faults and slabs, the deformational sequence and tectonic process of the suture zone and its neighbourhood, except for pre-orogenic tectonic evolution, were subdivided into three stages, viz. , subduction-related deformation, colli-sional deformation in the main orogenesis and deformation related to intra-continental adjustment. The fea-tures , ages, kinematics and dynamics of the deformation stages were described in this paper. At last, the com-plex process including indentation, extrusion or escape, strike-slipping and thrusting were summarized in a complete dynamic model.