Geochronology, geochemistry and tectonic implications of Weitingchagan composite pluton in northern segment of the Xing‐Meng Orogenic Belt

Abstract

We undertook zircon U–Pb dating and geochemical analyses of the Weitingchagan (WT) pluton in the Dong Ujimqi area, Northeast China, with an aim of determining their ages, petrogenesis and sources, which are important for understanding the Late Palaeozoic tectonic evolution of the Xing‐Meng Orogenic Belt. The WT pluton consists of coarse‐ to medium‐grained porphyritic granites in the core and medium‐ to fine‐grained monzogranites in the rim, contains abundant microgranular enclaves and is intruded by small amounts of muscovite monzogranites. The results of LA‐ICP‐MS zircon U–Pb dating indicate that the WT composite pluton formed during the Late Carboniferous–Early Permian with the ages ranging from 289 Ma to 312 Ma. Petrological and geochemical characteristics of the WT pluton were derived from the partial melting of crustal materials, and the AFC process played an important role in the magmatic evolution. The porphyritic granites are I‐type granite, and the monzogranites and muscovite monzogranites are highly fractionated I‐type granite. Combined with previous studies on the contemporaneous magma‐tectonic activities in the Uliastai Continental Margin, the study suggests that the WT pluton formed in an extensional environment, which may relate to the closure of the Palaeo‐Asian Ocean. Copyright © 2016 John Wiley & Sons, Ltd.