U-Pb and Hf isotopes of the detrital zircon in sediments from Wulasitai River in Xinjiang and its geological significance
U-Pb dating and Hf isotope composition analysis of detrital zircons from Wulasitai River were conducted by LA-MC-ICP.The results show that the U-Pb ages can be divided into 470～390 Ma,380～320 Ma and 310～260 Ma.By comparing and analyzing the published U-Pb ages in the river sands from the South Tianshan and combining with other evidence,the Paleozoic geological evolution process of the southern central Tianshan was discussed.The zircon population from 470 Ma to 390 Ma examined in this research and the zircon population from 460 Ma to 380 Ma found in rivers located in the southern region of the South Tianshan likely suggest a bidirectional subduction of the South Tianshan Ocean.Zircon grains dating from 380 Ma to 320 Ma probably record the subduction of the South Tianshan Ocean towards the north.Detrital zircons from 310 Ma to 260 Ma probably record the closure of the South Tianshan Ocean during the Late Carboniferous and subsequent syn-and post-collisional magmatism.The results of Hf isotopic composition show that abundant juvenile mantle material was gradually added to the magma formation in the Baluntai region,which may be related to the northward subduction and closure of the South Tianshan Ocean.
Detrital zirconU-Pb ageHf isotopeGeological significanceBaluntai region
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