内蒙古苏尼特左旗交其尔推覆构造带的发现及其地质意义

DISCOVERY OF THE JIAOQIER NAPPE STRUCTURAL ZONE IN SONID ZUOQI,INNER MONGOLIA AND ITS GEOLOGICAL SIGNIFICANCE

内蒙古苏尼特左旗中部交其尔一带发现一条近ＥＷ向延伸的推覆构造带。上元古界－下古生界浅变质岩以低角度向北推覆于晚古生代花岗岩基之上．推覆构造上盘的浅变质岩中发育有一套轴面向南倾的同斜倒转褶皱系，并伴有一系列向南倾的叠瓦状逆冲断面。下盘花岗岩中发育有较宽的糜棱岩带．沿推覆构造带分布有一系列的飞来峰及构造窗。这一构造带的发现，为纬向构造带的存在提供了有力证据，并显示了晚古生代末期以来地壳沿经线方向的强烈缩短。

he authors discovered a EW-extending nappe structural zone at Jiaoqier region in middle Sonid Zueqi, Inner Mongolia. The Upper Proterozoic-Lower Paleozoic epimetamorphic rock was thrust at a low angle onto the Late Paleozoic granite batholith. There formed a set of the homoclinally inverted folds with the fold-axial-plane inclined to the south in the epimetamorphic rocks and accompanied by a series of imbricated thrusts sloped to the south. The downwall of the over thrust, composed of the granite,developed a wider mylonitic zone. Along the nappe structure, there exist some klippes and structural windows. The discovery of the nappe structure strongly supports the existence of the latitudinal tectonic belt. And also, it illustrates the strong shortening of the crust along the meridional direction from the end of the Late Paleozoic.