Petrogenesis of Dahongliutan Biotite Monzogranite in Western Kunlun Orogen: Evidence from Zircon U-Pb Age and Li-Hf Isotope

The Dahongliutan pluton is located in the eastern part of the West Kunlun Orogenic Belt and is mainly consisted of biotite monzonitic granite, monzonitic granite and two mica granite. The Zircon LA-ICP-MS U-Pb dating of biotite monzonitic granite in the southeastern part of Dahongliutan intrusion shows that the emplacement age of biotite monzonitic granite is 214+1.8 Ma, indicating that the Dahongliutan pluton was formed in the Late Indosinian. The Dahongliutan pluton has higher value of δ7Li(0.76‰~3.25‰) and lower content of lithium(5.04~52.22)×10^-6. The biotite monzonitic granite has zircon εHf(t) values of -1.86 to 2.16, and the two-stage mode age ranged between 1113 and 1368 Ma. In the εHf(t) vs. age diagram,all the data points lie near the chondrite evolution line. The comprehensive research shows that the Dahongliutan pluton has derived from a mixed magma of mesoproterozoic crust and mantle.