LA-ICP-MS zircon U-Pb dating of the Late Triassic-Early Jurassic granites in the eastern part of Qimantag area and its geological significance

The Late Triassic-Early Jurassic granitic assemblage in the eastern part of Qimantag area has high SiO₂ content (72.18%~76.55%), high K₂O content (4.08%~5.32%) and obvious negative Eu anomaly (average σEu value being 0.28).The granitic assem-blage is composed of monzogranite and syenogranite, whose ages were precisely redefined by the LA-ICP-MS zircon U-Pb meth-od, being 205.1±1.0 Ma and 199.5±1.2 Ma respectively.This granitic assemblage has close relationship with skarn-type polymetallic deposits in Lalinggaoli area.Therefore, the authors preliminarily hold that the Late Triassic-Early Jurassic granitic assemblage is proba-bly an important ore-forming magmatic formation in the eastern part of Qimantag area.