Zircon Cameca U-Pb dating of granitoid gneisses in the Leiwuqi area of the eastern Tibet, China and its geological implication

The granitic gneiss was identified from the Jitang Group in the Leiwuqi area, eastern Tibet. All zircons from the granitic gneiss have shown regular oscillatory magmatic zoning and high Th/U ratios (>0.49), being consistent with those of magmatic zircons. So we quoted 206Pb/238U ages to indicate crystallization age of the granitic magma. Analysis of Cameca zircon U-Pb isotope yielded a weighted mean 206Pb/238U age of 282.1±0.9Ma. The age of granitic gneiss implies that this magmatism event was triggered by the southwest subduction of the Lancangjiang suture in early Permian. In another word, magmatic growth in Lancangjiang suture had been taken place during early Permian.