Zircon LA-ICP-MS U-Pb age of Early Cretaceous ignimbrite in southern Nagqu, Tibet

In northern Gangdise belt, Middle Triassic, Middle-Late Jurassic and Late Cretaceous magmatic activities exist, but Early Cretaceous magmatic activity was rarely reported. The authors sampled and analyzed systematically andesite porphyrite from Luoma area of Nagqu, Tibet. Two of the samples were dated by LA-ICP-MS zircon U-Pb dating, and their ages are 116.1±0.4Ma and 115.9±0.5Ma respectively. These ages are almost consistent with each other within the acceptable error range, thus representing the formation age. The authors hold that the Early Cretaceous magmatic activity did exist in northern Gangdise belt, which is of great significance in the study of the Early Cretaceous geological evolution.