桐柏-大别南缘变质流体变质-变形特征及构造意义

前人研究认为桐柏山主要是由桐柏核部杂岩单元组成,它是一个早白垩世花岗质片麻岩杂岩体,其中包含一定的三叠纪中高级变质岩石,后期一起经历相同的构造变形过程,在南北两侧形成剪切旋向完全相反的两条大型韧性剪切带,殷店-马垅剪切带就是南边的华南板块由SSE→NNW挤压作用下,在斜切大别造山带的方向上产生的右行平移断裂带。在野外进行地质考察的过程中,发现在该地区变质流体的分布具有一定的规律。因此,本文通过对殷店-马垅剪切带地质特征、走滑性质、糜棱岩及糜棱岩化岩石的变质变形,剪切带内长英质脉体物质组成、变形特征及物质来源等方面研究,探讨剪切带中变质流体的分布规律以及变质变形与变质流体之间的关系。

Metamorphic and deformational features of the metamorphic fluid at the southern fringe of the Tongbai-Dabie Mt

The Tongbai Mt was thought to be mainly composed of a Tongbai core complex unit, an early Cretaceous granitic gneiss complex that contains some Triassic medium to high grade metamorphic rocks,which, along with the host, had been subjected to late tectonic deformation,forming two big ductile shear zones of completely opposite shearing rotation,one on the southern side and the other on the northern. The Yindian-Malong shear zone in the south is a dextral strike-slip fault by the South China plate that cut the Dabie orogen obliquely as a result of a SSE-NNW compression. Field observations showed a regular pattern for the distribution of metamorphic fluid in the area. This paper,based on researches into geologic features and strike-slip nature of the Yindian-Malong shear zone, metamorphism and deformation of mylonite and mylonitized rock, material composition, deformational feature and material source of felsic veins in the zone,discussed the distribution pattern of metamorphic fluid within the shear zone,and the relationship of metamor- phism and deformation with the metamorphic fluid.