The geochronology and geochemistry of intrusive rocks in Bange area: Constraints on the evolution time of the Bangong Lake-Nujiang ocean basin
西藏班戈地区侵入岩年代学和地球化学: 对班公湖-怒江洋盆演化时限的制约

Field geological survey, U-Pb zircon chronology and rock geochemistry study shows that the intrusive rock of Bange region can be divided into four periods: early Early-Cretaceous quartz diorite and tonalite (138Ma±), the middle Early-Cretaceous granodiorite (132~128Ma), the middle-late Early-Cretaceous two-mica adamellite (130~114Ma), Late-Cretaceous adamellite (80Ma±). From the north to south, the petrogenic age of intrusive rock is from late to early, and the formation environment is from island-arc environment to syn-collosional orogenic environment to post-collisional environment. This result provides new information about the subduction polarity and evolution time of Bangong Lake-Nujiang ocean basin. The southward subduction of the Bangong Lake-Nujiang Ocean Basin is beginning before Middle Jurassic in Bange area, and it lasts to the middle Early-Cretaceous (130~125Ma), and finally close in the middle Early-Cretaceous (125Ma±). Then the collision of the Lhasa terrane and the Qiangtang terrane started, after 20~30Myr enter to post-collosional stage in early Late-Cretaceous (100~80Ma).