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念青唐古拉花岗岩是拉萨地块中部出露面积超过1500 km2的侵入岩基,岩性以中细粒黑云母二长花岗岩和中粗粒黑云母二长花岗岩为主;据岩体之间接触关系判断,中细粒黑云母二长花岗岩的结晶时代早于中粗粒黑云母二长花岗岩.应用高灵敏度高分辨率离子探针技术对念青唐古拉花岗岩代表性岩石样品的岩浆锆石进行U-Pb同位素测年,得到中细粒黑云母二长花岗岩的结晶成岩年龄为18.3Ma,中粗粒黑云母二长花岗岩的结晶成岩年龄为11.01 Ma.念青唐古拉黑云母二长花岗岩属拉萨地块内部已知的最年轻的巨型花岗岩侵入体,其岩浆侵位结晶与碰撞造山、地壳增厚、高原隆升、地壳东西向伸展存在密切的关系,与地壳局部熔融具有动力学成因联系.
The Nyainqentanglha granite is an intrusive rock base exposed in the central Lhasa massif with an area of more than 1,500 km2. The lithology is dominated by medium-fine biotite monzogranite and medium-coarse biotite monzogranite. According to the contact relationship between the rock mass It is concluded that the crystallization age of medium-fine biotite monzogranite is earlier than that of middle-coarse biotite monzogranite.Using high-sensitivity and high-resolution ion probe technique, the magmatic zircons of the representative rock samples from the Nyainqentanglha granite are subjected to U- Pb isotope dating, the crystallization age of the middle-fine biotite monzogranite is 18.3Ma, and that of the middle-coarse biotite monzogranite is 11.01 Ma. The Nyainqentanglha biotite monzogranite belongs to the Lhasa block The youngest giant granite intrusions known internally have a close relationship with collision orogeny, thickening of the crust, uplift of the plateau and east-west crustal extension, and have a kinematical connection with local melting of the crust.