The Gangdese orogenic belt in southern Tibet records a succession of arc-trench-basin assemblages formed by the Neo-Tethyan subduction and the subsequent India-Asian collision. However, the geochronology and geodynamics of S-type granites in the northern part of the Gangdese belt are disputed. This paper describes ~190 Ma S-type granitoids outcropped in the Nyainqêntanglha Range, South Tibet, focusing on their petrogenesis and their relationship with contemporaneous magmatism. There are three distinct groups of granitoids, based on field relationships, petrology, and geochemistry. The coarse-grained Group I and II granitoids are large, sheet-like bodies and exhibit high contents of incompatible elements and negative Eu anomalies. The fine-grained Group III granites form small laccoliths and have low REE contents and positive Eu anomalies. The negative ε_Nd(t) and ε_Hf(t) values, abundant inherited zircons, moderately light REE and LILE enrichment, and HFSE depletion indicate that the Damxung granitoids were derived mainly by the partial melting of a metapelitic source. Further studies proposed that group I and II samples with high contents of incompatible elements and negative Eu anomalies represent fractionated melts, whereas group III samples with low REE contents and positive Eu anomalies represent cumulates. The age distribution pattern of inherited zircons supports the interpretation that the Lhasa terrane rifted away from the northern margin of the Indian plate. Considering previously published data in the Lhasa terrane, we suggest that the Early Jurassic magmatism could be related to a period of subducted oceanic slab roll-back, which provides new insights into the evolution process of the Neo-Tethyan ocean realm.

藏南冈底斯造山带记录了一系列由新特提斯俯冲和随后的印度-亚洲碰撞形成的弧-海沟-盆地组合。然而，冈底斯带北部S型花岗岩的年代学和地球动力学存在争议。本文描述了藏南念青唐古拉山脉出露的~190 Ma S型花岗岩，重点介绍了它们的岩石成因及其与同期岩浆作用的关系。根据油田关系、岩石学和地球化学，有三组不同的花岗岩。粗粒 I 族和 II 族花岗岩体为大型片状体，不相容元素含量高，Eu 负异常。细粒III族花岗岩形成小石块，稀土元素含量低，Eu正异常。_Nd (t) 和 ε _Hf(t) 值、丰富的继承锆石、中等轻的 REE 和 LILE 富集以及 HFSE 耗竭表明当雄花岗岩主要来自变泥质源的部分熔融。进一步的研究提出，不相容元素含量高且Eu负异常的I组和II组样品代表分馏熔体，而REE含量低且Eu正异常的III组样品代表累积。继承锆石的年龄分布模式支持拉萨地体从印度板块北缘断裂的解释。考虑到先前在拉萨地体中发表的数据，我们认为早侏罗世岩浆活动可能与俯冲大洋板块回滚时期有关，