Petrogenesis of an Early Permian bimodal intermediate‐felsic suite in the East Junggar in Central Asian Orogenic Belt and tectonic implications

The bimodal intermediate‐felsic suites are rare, and their petrogenesis remains unsolved. Here, we report a bimodal intermediate‐felsic magmatic suite from East Junggar (NW China) composed of rhyolites, basaltic andesites, and andesites. The basaltic andesites and andesites are porphyritic with phenocrysts predominantly of plagioclase. The rhyolites are porphyritic with phenocrysts of alkali‐feldspar, quartz, and minor plagioclase. LA–ICP–MS zircon U–Pb dating yielded an age of 284 ± 2 Ma for rhyolites. The basaltic andesites and andesites show SiO2 ranging from 54.67 to 58.26 wt%, and exhibit moderate TiO2 (1.45–1.77 wt%), and K2O (1.59–2.07 wt%) with low MgO (1.51–2.25 wt%). They display enrichment in HFSE and LILE together with negative Th, Nb, Ta, Ti anomalies, and exhibit low 87Sr/86Sr(t) ratios (0.7040–0.7046), high positive εNd(t) values (+5.82 to +6.16) and young TDM ages (75 wt%), negative Nb, Ta anomalies and significant depletion in Ba, Eu, Sr, Ti, and P. They also show high εNd(t) values (+5.51 to +7.08) and young TDM ages (