LA-ICP-MS zircon U-Pb dating and geochemical characteristics of Early Cretaceous volcanic rocks in Longling-Ruili fault belt, western Yunnan Province

Based on a study of the tectonic mélange between the Longling-Ruili fault and the main Gaoligong fault with the help of geological mapping and sections，the authors found the lentoid and intermittent medium-acidic volcanic rocks, which belong to the Triassic Zhaduo Formation and lie in Longling-Ruili fault. The zircon U-Pb dating age of 130.0±1.7Ma of the volcanic rocks was obtained. It is confirmed for the first time that there exist early Cretaceous volcanic rocks in the Longling-Ruili fault of western Yunnan Province. The geochemical characteristics of the volcanic rocks suggest that they were island arc tholeiites（IAT）and should be the response to the closure of the Nujiang ocean in the Early Cretaceous，related to westward subduction of Bangong Co-Nujiang oceanic crust and eastward subduction of Neo-Tethys oceanic crust.