龙泉关韧性剪切带同变形花岗岩的构造特征及其独居石定年

Syn-deformational granites of the Longquanguan ductile shear zone and their monazite electronic microprobe dating

龙泉关韧性剪切带强变形部位发育一系列平行剪切带走向展布的花岗岩脉体，构造变形特征表明它们可能是同变形花岗岩，是剪切作用下围岩部分熔融的产物。通过独居石电子探针定年，测得龙泉关韧性剪切带的年龄分别为：主变形幕发生于1877～1846Ma，第2个变形幕发生于1812-1782Ma，晚期1725Ma左右又经历了流体活动。龙泉关韧性剪切带的发生、发展与华北克拉通中部带古元古代晚期的变质事件同期，是东、西陆块碰撞的一个主要剪切带。

A series of prolonged granitic intrusions occur along the foliation of the Longquanguan ductile shear zone. Petrological and structural characteristics show that they are possibly syn-deformational granites resulting from partial melting of the country rock caused by shearing. The electronic microprobe dating of monazites from these granites shows that the major deformation episode took place at 1 877-1 846 Ma, the second deformation episode occurred at 1 812- 1 782 Ma, and the fluid activities happened in the late stage at about 1 725 Ma. The major deformation of the Longquanguan ductile shear zone occurred synchronously with the tectonic events in the central zone of the North China craton in the Late Paleoproterozoic, and this shear zone seems to have been one of the main shear zones formed by the collision of eastern and western blocks.