Abstract:Zircon UPb dating of the South Altun granites shows that, in the western segment of the South Altun, granite plutons at Yigan Village south of Qiemo County are aged 352±4, 349±2, and 343±3 Ma; while in the eastern segment of the South Altun, granite plutons north of Baiganhu Village are aged 447±4, 444±5, and 448±2 Ma, granites west of Mangya Town are aged 444±6 and 435±4 Ma, the granite from the Aketi Mountains is aged 265±2 Ma, Chaishuigou granite is aged 406±5 Ma, Changchungou quartz diorite is aged 469±3 Ma, and the granite north of Mangya Town is aged 462±8 Ma. Based on previous studies in conjunction with granite dating and geochemical study results in this paper, the South Altun granite can be divided into five episodes: episode 1, characterized by the granite association of quartz diorite+granodiorite+monzogranite, with affinities of Itype granite and an age of>460 Ma; episode 2, characterized by the granite association of granodiorite+monzogranite+syenogranite, with geochemical affinities of Itype granite and an age of 435~450 Ma; episode 3, characterized by the granite association of quartz monzonite+syenogranite+alkali feldspar granite, with affinities of Atype granite and an age of 385~411 Ma; episode 4, characterized by the granite association of granodiorite+monzogranite with an age of 343~352 Ma, with geochemical affinities of Stype granite; and episode 5, characterized by the granite association of quartz diorite+monzogranite, with geochemical affinities of Itype granite and an age of 265 Ma. Based on the results of the above studies in conjunction with regional geological characteristics, it is considered that episode1 granitic magma activity might be related to the subduction of oceanic crust, episode2 magma activity might belong to postcollisional magma activity, episode3 magma activity might be related to the isostatic adjustment of orogen blocks after plate collision, episode4 magma activity might be related to Tethyan tectonic activity, and episode5 magma activity might be related to the Altun fault activity.