Abstract:
E-W-trending megaporphyritic granodiorite in the Gangdise back-arc fault uplift area has a sin-gle-grain zircon U-Pb age of 217Ma.For the first time it is confirmed that Indosinian magmatic activity occurred in the Gangdise area and that200Ma granodiorite is widely distributed there.The latest statistical data indicate that the direction of the paleocurrents of the Upper Triassic Langjiexue Group on the south-ern side of the Yarlung Zangbo suture is from north to south and that the clastic materials have the fea-tures of an orogenic belt.So an uplift probably existed in the Late Triassic in the Gangdise area.Magmatic activity and sedimentation indicate that Gangdise has a complex evolutionary history.The authors consider that the orogenic belt formed by the Late Triassic-Early Jurassic tectono-thermal event in the area should be called Paleo-Gangdise.