尼玛区幅、热布喀幅地质调查新成果及主要进展

New results and major progress in regional geological survey of the Nyima District and Rabka sheets

证实测区内发育含有华夏生物群分子的上二叠统敌布错组。查明班公湖-怒江结合带内发育一套中侏罗世稳定型浅海碎屑岩沉积。发现结合带南侧存在中晚侏罗世滞后型岛弧火山岩和后碰撞型SP花岗岩带,认为班公湖-怒江结合带在测区表现为向南俯冲的构造极性,闭合时间在中侏罗世以前。根据格仁错地区推覆构造和帮勒右行斜冲挤压韧性变形带初步研究结果,提出永珠-格仁错构造带是一个具有多期活动特征的区域性构造带,并属于狮泉河-申扎-嘉黎构造带的一部分。识别出冈底斯岩浆弧存在2个相对集中又有所套叠的岩带。发现冈底斯中段存在一个矽卡岩型多金属成矿带,在冈底斯北坡古近纪盆地日贡拉组中发现砂岩型铜矿。

It is confirmed that there occurs the Upper Permian Dibucuo Formation containing elements of the Cathaysian biota in the survey area. It is ascertained that a sequence of Middle Jurassic stable neritic clastic sediments occurs in the Bangong Co-Nujiang juncture zone, and that a suite of Middle-Late Jurassic lag-type island-arc volcanic rocks and a Middle-Late Jurassic post-collision SP granite belt occurs on the south side of the juncture zone. The authors think that the Bangong Co-Nujiang juncture zone has been subducted toward the south in the survey area and closed before the Middle Jurassic. Based on a study of the thrust nappe structure in the Gyaring Co area and the Bangle dextral inclined compressional ductile formation belt, the authors propose that the Yunzhug-Gyaring Co tectonic belt is a regional one with the features of multi-phase activities and a part of the Shiquanhe-Xainza-Lhari tectonic belt. The Gangdise magmatic arc can be divided into two rock belts which are relatively concentrated and overlap each other to a certain extent. A skarn-type polymetallic metallogenic belt occurs in the central segment of the Gangdise Mountains and a sandstone-type copper deposit was found in the Rigongla Formation of the Paleogene basin on the north slope of the Gangdise Mountains.