甘肃公婆泉地区志留纪弧盆体系前寒武纪基底的发现及找矿意义

THE DISCOVERY OF PRECAMBRIAN BASEMENT IN ARC-BASIN SYSTEM OF SILURIAN AND ITS SIGNIFICANCE FOR PROSPECTING IN GONGPOQUAN AREA,GANSU

公婆泉地区为志留纪沟、弧、盆发育地区，为铜和多金属有利成矿带．作者通过野外和室内综合研究，对前人所确定的下志留统勒巴泉群、尖山地区中、上志留统“公婆泉群”、马鬃山主峰东侧“下石炭统、下二叠统”等变质岩系分别作了Ｓｍ－Ｎｄ、Ａｒ－Ａｒ、Ｒｂ－Ｓｒ法测年研究，获得新数据。其时代为：尖山地区“公婆泉群”变质火山岩时代为震旦纪至早古生代，勒巴泉地区勒巴泉群、马鬃山主峰东侧“下石炭统、下二叠统”变质岩时代分别为长城纪及前长城纪。论证了公婆泉地区弧盆的基底属古陆壳性质．

ongpoquan area,as a Silurian tranch-arc-basin system,is a zone favorable for copper and polymetal mineralization.Based on the fieldwork and indoor study,this paper provides a series of new data on the original metamorphic rocks by using Sin-Nd,Ar-Ar and Rb-Sr dating methods:they were Lower Silurian Lebaquan Group,Mid-Upper Silurian Gongpoquan Group in the Jianshan area and Lower Carboniferous and Lower Permian rock series in the east of Mazongshan Peak.According to these new data,the metamorphic volcanic rocks of Gongpoquan Group are considered as the in Sinian-Early Palaeozoic;Lebaquan Group in the Lebaquan area as the Changcheng Peroid;and the Lower Carboniferous and Lower Permian,as Pre-Changcheng Period.So it has been concluded that the basement of arc-basin in the Gongpoquan area is of palaeo-crust features.