中文摘要：

改则地区的嘎布扎花岗闪长岩侵入于南羌塘地体南缘的侏罗系色哇组,为研究班公湖—怒江缝合带的演化提供新的约束。岩浆锆石的LA-ICP-MS U-Pb年龄为（143.8±0.5）Ma,显示花岗闪长岩的侵位时代为晚侏罗世—早白垩世之交。花岗闪长岩具有准铝质I型花岗岩的特点,属于高钾钙碱性岩石系列;稀土元素为轻稀土富集型,存在弱的Eu负异常;明显富集Rb、Ba、K、Th、U等大离子亲石元素,而亏损Nb、Ta、P、Ti等高场强元素。研究表明花岗闪长岩的岩浆源区可能经历了陆壳物质、俯冲沉积物与幔源楔等不同性质的岩浆混合,并经历一定程度的分离结晶作用形成。改则嘎布扎花岗闪长岩形成于班公湖—怒江中特提斯洋晚侏罗世—早白垩世向北俯冲的岛弧环境。

英文摘要：

The Gabuzha granodiorite in Gerze area intruded into the Jurassic Sewa Formation at the southern edge of the southern Qiangtang terrane, and can be used to constrain the evolution of Bangong Co-Nujiang River suture zone. LA-ICP MS zircon U-Pb dating yielded a weighted mean age of （143.8±0.5） Ma, suggesting that the Gabuzha granodiorite formed during late Jurassic to early Cretaceous. The Gabuzha granodiorite is metaluminous I-type granite and belongs to high-K calc-alkaline series. Its REE model is characterized by enrichment of light REE, and Eu shows weak negative anomaly. Large ion lithophile elements areobviously enriched in Rb, Ba, K, Th and U. High field strength elements Nb, Ta, P and Ti show strong depletion. The results show that the magma source of Gabuzha granodiorite might have been derived from mixture of continental crust materials, subducting sediments and mantle- derived wedge, and experienced a certain degree of separation and crystallization as well. The Gabuzha granodiorite formed in an island arc environment related to northward subduction of the Bangong Co-Nujiang River Meso-Tethys Ocean beneath the Qiangtang terrane.