The discovery of the mafic-ultramafic melange in Kekesha area of Dulan County, East Kunlun region, and its LA-ICP-MS zircon U-Pb age

Abstract：The East Kunlun region is a compound continental orogenic belt formed through Jinningian，Caledonian，Hercynian and Indosinian multi-stage cycles and contains quite a few important tectonic boundaries．Recently a suite of mafic-ultramafic melange was found in Kekesha area，15 km west of Qingshuiquan area, during the 1:50000 regional geological survey． The LA-ICP-MS zircon U-Pb isotopic age of the gabbro from the mafic-ultramafic melange is about（509.4±6.8）Ma（MSED=1.4），corresponding well to the age of the Qingshuiquan ophiolite near the Mid-Kunlun fault．This result thus provides new chronological evidence for the western extension of the Qingshuiquan ophiolite zone and the evolution of the eastern part of the East Kunlun region in Early Paleozoic．