Detrital zircon U-Pb and Ilf isolopic study of Ihc Yushulazi Formation in the Gaizhou-Zhuanghc area of the eastern Liaoning: Constraints on the cruslal evolution of the North China C rat on.

Abstract

As the oldest stable sedimentary cover sequences on the crystalline basement of eastern Liaoning Province, the Yushulazi Formation outcrops in the Gaizhou-Zhuanghe area and unconformably overlies the Paleoproterozoic Liaohe Group. Therefore, its depositional age, provenance and sedimentary environment can provide important information for the understanding of the crustal evolution. However, very few data about its depositional age and provenance information have been reported. Based on our new detail field geological mapping results, in this study we carried out zircon U-Pb dating and Hf isotopic analysis on typical samples from the lower, middle and upper levels of the Yushulazi Formation. U-Pb zircon dating results show that the Yushulazi Formation deposited sometime after ~ 1803Ma. It shows a large similarity with the adjacent Changzhougou Formation of the Mesoproterozoic Changcheng System in age spectrum, provenances and sedimentary cycles. The adjacent Archean basement of Longgang and Liaonan blocks, the Paleoproterozoic Liao-Ji granitoids may provide the major source for the Yushulazi Formation. Moreover, detrital zircon Hf isotopes reveal an old Hf model age of ~4. 10a, and a peak model age of 3. 1 ~ 2. 70a, indicating that the North China Craton experienced the multiple crustal growth events during the Meso- A nd Neo-Archean.