安徽东部南黄变质核杂岩初步研究

PRELIMINARY STUDY ON THE NANHUANG METAMORPHIC CORE COMPLEX IN EASTERN ANHUI

南黄变质核杂岩位于扬子地块北东缘滁州-巢湖前陆褶皱冲断带的西侧,地表呈不规则穹形构造,核部出露上元古界张八岭群北将军组,四周为张八岭群西冷组环绕,两者间发育有缓倾斜韧性断层。南黄变质核杂岩以具有三层式结构为特征,变质杂岩核为上太古界南黄片麻岩套,中间韧性流变层由中元古界大理岩段及上元古界张八岭群组成,震旦系沉积盖层零星出露于南东,指向构造反映由北北西往南南东的剪切滑动。同构造期闪长玢岩K-Ar法年龄147±4.4Ma,表明南黄变质核杂岩是燕山运动造山期后伸展作用的产物,属陆内造山型变质核杂岩。

The Nanhuang metamorphic core complex is located on the west side of the Chuzhou-Chaohu foreland fold-thrust belt at the northeastern edge of the Yangtze massif.It is an irregular dome structure for the surface,and the core part has the outcrop of the Proterozoic Beijiangjun Formation of the Zhangbaling Group,which is surrounded by the Xileng Formation of the same group,in between is a flat-dipping ductile fault.The Nanhuang metamorphic core complex is characterized by a three-tier structure,with the the core of metamorphic complex being the Upper Archean Nanhuang gneiss s u i t e,middle ductile rheological layer composed of the Middle Proterozoic marble member and the Upper Proterozoic Zhangbaling Group,the southeast part sporadically of outcrops of the Sinian sedimentary cover,and the directional structure reflecting a shear slip from NNW to SSE.The syntectonic K-Ar age of diorite porphyrite 147±4.4Ma indicates that the Nanhuang metamorphic core complex is a product of post-orogenic Yanshan Movement,intracontinental orogenesis.