江汉平原东部构造特征与演化

本文论述了江汉平原地区东部区域构造格架与局部构造样式及其构造演化,指出该地区中古生界以发育挤压性构造为主,具有对冲干涉、南北分带、纵向叠置的结构特征。全区分为南部江南-雪峰滑脱推覆构造带、中部对冲(背冲)构造带、北部秦岭大别推覆构造带三个主体构造带。多期次构造变形变位及岩浆活动作用,发育了挤压构造、压扭走滑构造、刺穿和隐刺穿构造、张性构造四类基本构造样式。一般认为震旦纪至早、中三叠世本区及中扬子区经历了两期板块汇聚、增生、裂解、俯冲、陆内碰撞造山的构造旋回;之后经历了晚三叠世前陆斜坡演化阶段;侏罗纪末期陆内造山、挤压褶皱演化阶段;侏罗纪后-早白垩世剥蚀夷平、岩浆岩活动改造演化阶段;中晚白垩世-古近纪构造负反转、断陷演化阶段;新近纪构造体制再次正反转、区域挤压抬升演化阶段。多期构造运动导致多种原型盆地改造叠加使江汉平原东部地区的构造格局复杂多变。

Structural Style and Tectonic Evolution of the Eastern Part of Jianghan Basin in the Jianghan Plain Region

This paper discusses the regional structural framework, local styles, and tectonic evolution of the east part of Jianghan Plain. The area was dominated by compressive tectonic structures in Mesozoic-Paleozoic, and structurally characterized by ramp interference, south-north zonation, and vertical overlap. Three major tectonic belts were recognized in the area: Jiangnan-Xuefeng décollement nappe in the south; ramp (back) tectonic belts in the central; Qinling-Dabie nappe structure in the north. The multi-stage tectonic deformation, displacement and magmatic activity led to the development of four types of basic structural styles: compressional tectonics, compressional strike slip tectonics, diaper and blind diaper tectonics, and extensional tectonics. It is generally believed that during the period of Sinian to Early and Middle Triassic, the studied area and Mid-Yangtze Region experienced two episodes of tectonic cycle: convergency, accretion, displacement, subduction, intracontinental collisional orogenesis of the plates. And after that, they experienced foreland slope in Late Triassic, intra-continental orogeny and compressive fold in Late Jurassic, denudation planation and reformation of magmatic rocks in Late Jurassic to Early Cretaceous, negative structure inversion and fault depression in Middle and Late Cretaceous to Paleaogene, the another positive inversion of tectonic regime and regional compression uplift in Neogene. Multi-stage tectonic movement and multi-type superposition and modification of the prototype basin contribute to the complexity of structural framework of the east part of Jianghan Plain.