西藏1∶5万班戈县西南地区四幅区调成果与展望

西藏1∶5万班戈县西南地区四幅区域地质矿产调查为青藏专项地质调查项目。该项目取得的主要成果为:1发现了区内寒武系火山岩呈角度不整合覆盖于念青唐古拉群之上,其内部划分为3个岩性段;新建了上寒武统他多雄组。2对下奥陶统扎扛组进行了解体;新建了芙蓉统龙郊组。3通过详细的地质填图,在永珠蛇绿混杂岩带中新发现一套沉积混杂岩,认为该混杂岩区域延伸稳定;新建了晚侏罗世索尔岩组。4对蛇绿岩填图单元进行了解体,由超镁铁质岩、辉长岩、席状岩墙群、枕状玄武岩岩片、放射虫硅质岩组成,新建了晚侏罗世永珠蛇绿岩群。5确定了念青唐古拉群,新识别出的变质花岗岩形成时代为中新元古代,为研究古印度地盾北缘罗迪尼亚大陆形成期和裂解期的构造热事件提供了新资料。

Achievements and Prospects of Four 1:50 000 Regional Geological Survey Projects in Southwest Bangor County,Tibet

As a part of the special geological survey project of Qinghai-Tibet, the four 1:50 000 regional geological and mineral resources survey subprojects in southwest Bangor county have achieved some achievements. (1) The Cambrian volcanic rocks cover the Nyainqentanglha Group in angular unconformity and consist of three rock units, and the Upper Cambrian Taduoxiong Formation which is a new rock unit have been established. (2) The Furongian Longjiao Formation is detached from the Lower Ordovician Zhakang Formation. (3) A suite of sedimentary melange with stable regional extension have been found in the Yunzhug ophiolite melange belt during geological mapping, and termed as Late Jurassic Suoer Formation. (4) The basic rock unites, composing with ultramafic rocks, gabbro, sheeted dike complex, pillow basalt and radiolarian chert, which comprise the Late Jurrasic ophiolite suite are recognized. (5) A series of metamorphic granites from the Nyainqentanglha Group form in Meso-neoproterozoic and provide new data for tectonic thermal events study during formation and breakup of the Rodinia continental which take place on the north margin of ancient India shield.