Detrital zircons from the Yanchang Formation in Hancheng area,southeastern Ordos Basin U-Pb chronological characteristics and provenance indication significance
Focusing on the provenance evolution of the Yanchang Formation in the Middle and Late Triassic in the southeastern part of Ordos Basin,this paper investigates the provenance characteristics of the Yanchang Formation in the southeastern part of the basin by using detrital zircon U-Pb chronology.The results show that the U-Pb age spectra of detrital zircons from different strata of Yanchang Formation in Xufengchuan area,Hancheng are consistent,and the peak segments are mainly concentrated in the late Late Paleozoic(250～263 Ma)and late Paleoproterozoic(1 689～1 774 Ma,1 867～1 885 Ma)and early Paleoproterozoic(2 490～2560 Ma),the Archean ages are only scattered,while the Middle Proterozoic and Early Paleozoic ages are missing.The comprehensive provenance comparison shows that the provenance of Yanchang basin in Hancheng area mainly comes from the North China Craton and Yinshan Orogenic belt in the northeast of the basin,while the provenance characteristics of the south margin of North China Plate and the south Qinling area are not obvious.These provenance characteristics are in sharp contrast to the complex and variable provenance characteristics of the extended period in the southwest of the Ordos Basin,suggesting that the southeast of the Ordos Basin has stable northeast provenance characteristics.It is speculated that there are still deep lacustrine sediments separating the southern provenance during the extended period in the southern part of the Ordos Ba-sin,which is of great significance for the study of the evolution of the lake basin during the extended period.
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