西藏尼玛县南部中晚侏罗世松木果强过铝花岗岩带的发现及其意义

Discovery of the Mid-Late Jurassic Songmuguo strongly peraluminous granite belt in the southern part of Nyima County, Tibet, and its significance

班公湖-怒江结合带南80-100km处,分布着一条东西长度超过100km的强过铝(SP)花岗岩带,由松木果岩体、央雄勒岩体等数个岩体构成。岩体侵位于昂孜错-色热巴断裂南北两侧,包含5次侵入事件,均属高钾钙碱性强过铝花岗岩类,是后碰撞型SP花岗岩,时代为中-晚侏罗世。研究认为,岩带的形成与班公湖-怒江结合带尼玛段中侏罗世之前向南俯冲闭合作用有关,SP花岗岩带的有限长度和相对区域上早的侵位时代还表明,中特提斯洋是多块体、分时段闭合的。

A strongly peraluminous （SP） granites belt, extending over 100 km from east to west, is distributed 800-100 km south of the Bangong Co-Nujiang junction zone. It consists of several intrusions such as the Songmuguo intrusion and Yangxiongle intrusion. The intrusions are emplaced on both south and north sides of the Ngangz6 Co-Sereba fault and involve five intrusion events. They all belong to high-K, calk-alkaline, SP granites and are post-coUisional SP granites of Mid-Late Jurassic age. Study suggests that the formation of the belt is related to the southward subduction and closing of the Nyima segment of the Bangong Co-Nujiang junction zone before the Middle Jurassic. The limited length of the SP granite belt and its earlier regional emplacement time show that the Meso-Tethys is composed of multiple blocks and dosed in different times.