Zircon U-Pb,Trace Element and Hf Isotopes of Pyroclastic Rocks from the Drilling Cores in the Junggar Basin

Simultaneous in-situ analyses of single zircon LA-ICP-MS U-Pb age and trace elements and Hf isotope systematic analysis from the Batamayineishan Formation.The volcanic rock was obtained from drill well Db1 and Y1on the north-central Luliang uplift within the Junggar Basin.The internal structure of zircon,Th/U ratios,REE patterns show that all samples are magmatic zircon.The results showed that:①the youngest age is interpreted as the formation age of the studied formation by measured the two zircon samples,that is Late Carboniferous;②zircon U-Pb ages display Mid-Late Proterozoic 1447~1410Ma,885~559Ma and the age record from early or middle Paleozoic 536~420Ma,401~360Ma,359~303Ma,indicating that the Junggar Basin experienced a complex of continental crust formation and evolution of the multi-stage process;③trace elements of zircon suggest that the basement of north-central Junggar basin in pre-Permian is composed of granite and mafic intrusive activity continental basement by granite,syenite,basalt and dolerite;④zircon Hf isotope analysis showed thateHf(t)values have a relatively great variation ranging from +4.6to+19.0,demonstrating that at least two source materials have contributed to the zircon host rock generation,suggesting that magma rise and emplacement process was contaminated by ancient basement material components.