【摘要】 商城 麻城断裂带在大别山的构造格局中占有重要地位,但长期以来对其形成时代缺乏精细的测年研究,有鉴于此,我们采用断裂带糜棱岩中黑云母单矿物⁴⁰Ar-³⁹Ar年代学方法测定其变形时代。结果表明,商麻断裂带形成于226 Ma左右,是扬子和华北两大板块碰撞后期的产物,是一条垂直于造山带走向的横向平移断层。在商麻断裂带的转换调节下,其两侧地块发生差异位移、抬升和相对旋转,导致东西两侧的超高压岩石的折返出露呈现出不同的特征。更多还原

【Abstract】 The Shangcheng-Macheng fault belt is an important NNE-trending fault in the Dabie oro-gen, which divides the orogenic belt into two blocks: Hongan block and Dabie block. In this study, the 40Ar-39Ar dating method is employed for the biotite from the mylonite of the fault belt to determine its formation time. The result indicates that the Shangcheng-Macheng fault belt occurred around 226 Ma, which developed in the late stage of the collision between the North China plate and the Yangtze plate. The Shangcheng-Macheng fault belt is a wrench fault that is perpendicular to the orogen strike. Owing to the transforming and adjusting effects of the Shangcheng-Macheng fault belt, there occurred different displacement, uplift and relatively rotation with the Hong’an and Dabie blocks, which resulted in different exhumation characteristics of the ultrahigh-pressure metamorphic rocks in the two blocks.更多还原