LA-ICP-MS zircon U-Pb age of quartz diorite at the Kekesha area of Dulan County, eastern section of the East Kunlun orogenic belt, China and its significance

After detailed field survey and indoor analysis, the quartz diorites exposed at the Kekesha area of Dulan, eastern section of the East Kunlun orogenic belt, include four types of rocks: (1)Gray-dark gray medium grained quartz diorite; (2) Gray medium grained gneissic quartz diorite; (3)Gray medium-coarse grained amphibole quartz diorite; (4)Light flesh-red medium-fine grained porphraceous adamellite. LA-ICP-MS method is used to determine the zircon U-Pb isotope age of the rock, which shows that the zircon 206Pb/238U weighted average age of the sample 11013 is 515.2±4.4Ma (MSWD=2.5) and defines the crystallization age of the rocks in Middle Cambrian period. It indicated that East Kunlun orogenic belt had experienced a magmatism event during the early Caledonian.