rovenance analysis of Early Cretaceous Huixian-Chengxian basin, western Qinling orogenic belt, China: constraints from zircon U-Pb geochronology

Detrital zircon U-Pb ages of three samples from the granite and sandstones in Huixian-Chengxian basin were measured by the LA-ICP-MS method. The sample of 09TB4, 09DPL25 and 09DPL41 respectively records 25, 89 and 123 age data. The granite boulder ages are shown in 210.8±0.6Ma and 218.8±1.8Ma, which are consistent with Miba granite age dated by Sun et al. Statistical analyses show that the provenances of Zhoujiawan Formation are 186~240Ma and 629~1182Ma rocks while main provenance ages of Jishan Formation are 179~233Ma, 305~459Ma and 632~1281Ma. Detrital zircon data show that different distribution and provenance are variable. All of zircons U-Pb ages indicate that sediments of Tianjiaba Formation are mainly from Miba granite, and Proterozoic rocks provide sediments for Zhoujiawan Formation besides Miba granite. The Carboniferous, Devonian to Ordovician rocks are subordinate provenance for Jishan Formation. These also showed that the lower Triassic-Permian rocks didn′t occur in southern margin of Huicheng basin. There occured a few magmatic activities during 207 Ma (206 Ma), 448Ma (428Ma), 791 Ma (874Ma) periods and developed regional metamorphism in 915Ma (910Ma) in the southern areas of Huicheng basin.Together with the exsiting data, one detrital zircon age in Zhoujiawan Formatin strongly suggests that the basement rocks in the western Qinling orogenic belt were formed in the Neo-Archean period.