中文摘要：

对班公湖-怒江缝合带中段达如错地区侵入于蛇绿岩中的花岗斑岩进行了详细的野外调查及岩石学、地球化学、锆石U-Pb和Hf同位素研究。用LA-ICP-MS技术测得达如错花岗斑岩的锆石U-Pb年龄为110±1Ma,该年龄被解释为达如错花岗斑岩的形成年龄,并且锆石具有明显负的εHf（t）值（-5.5~-2.6）。全岩地球化学资料表明,达如错花岗斑岩具有高钾钙碱性系列岩浆岩的特征,且A/CNK〉1.1,富集Rb、Ba、Pb、Th,亏损Ta、Nb、Ti,轻稀土元素相对重稀土元素富集,同时具有明显的负Eu异常。以上特征表明,花岗斑岩属于强过铝质S型花岗岩。结合前人资料认为,达如错花岗岩岩体形成于同碰撞的构造环境,是加厚的大陆地壳发生重熔的产物,其形成还可能与同时期拉萨地块底部软流圈热物质上涌有关。班公湖-怒江缝合带中段在110Ma左右已经闭合,并发生了陆-陆碰撞。花岗斑岩侵入于蛇绿岩中,暗示110Ma之前该地区蛇绿岩就已经形成。

英文摘要：

Located in the middle part of the Bangong Co-Nujiang PAver suture zone, the Daru Co granite porphyry was intruded into the ophiolite of this suture zone. In this study, the authors performed detailed field investigation, petrological and geochemical study, and zircon U-Pb and Hf isotopic analysis of the Daru Co granite porphyry. Using the LA-ICP-MS technique, the authors obtained the U-Pb age of 110＋ 1Ma for the Daru Co granite porphyry, and this age is interpreted as the formation age of granite por- phyry. The Daru Co granite porphyry has pronounced negative zircon ε Hf（t） values in the range of-5.5~-2.6. Whole-rock geo- chemical data show that it is characterized by high K calc-alkaline series, A/CNK higher than 1.1, enrichment of LREE, P,b, Ba, Pb and Th, and depletion of Ta, Nb and Ti. All samples show negative Eu anomaly. These features indicate that the Daru Co granite porphyry belongs to the peraluminous S-type granite. It is considered that the Dam Co granite porphyry might have been formed by partial melting of the thickened continental crust in a syn-collision setting, and it was probably related to the hot asthenosphere up- welling under the Lhasa block. The ocean basin had been closed and continental collision started before ll0Ma in the middle part of the Bangong Co-Nujiang River suture zone. Furthermore, the ophiolite in this area should be formed before 110Ma in terms of the relationship between the Daru Co granite porphyry and ophiolite.