Zircon U-Pb geochronology, whole-rock geochemical and Lu-Hf isotopic constraints on the petrogenesis of highly evolved I-type rhyolites in the Loei fold belt and their tectonic implications

摘要

Southeast Asia is composed of a number of terranes that were successively rifted off from Gondwana, drifted northward and accreted to each other.The Indochina Block originated from eastern Gondwana and was rifted away in the Early Devonian (Metcalfe, 2013).The Loei fold belt, situated in the west of Indochina, has been intensely studied regarding the controversy over its regional tectonic evolution (Intasopa and Dunn, 1994;Panjasawatwong et al., 2006;Udchachon et al., 2011;Vivatpinyo et al., 2014).Recently, we found Silurian rhyolites in the Loei fold belt, and the identification of lower Paleozoic volcanic rocks is of significant importance in studying the geological and tectonic evolution this terrane and the reconstruction of Gondwana.We obtained zircon U-Pb ages for the rhyolites, as well as their whole-rock geochemistry and Hf isotope compositions.