Abstract:
This paper is the result of geological survey engineering.
Objective The 5th member of Nenjiang Formation, along with Sifangtai Formation and Mingshui Formation at the southern Daqing placanticline of the northern Songliao Basin, has been identified in recent years as important uranium–bearing stratigraphic units. However, the absence of comprehensive studies on provenance evolution has severely hindered further understanding of both palaeogeographic conditions and uranium mineralization mechanisms in this region.
Methods In this study, we conducted LA–ICP–MS dating of detrital zircons and compared the results with the ages of surrounding rock masses collected around the basin. Integrated the sandstone composition and heavy minerals characteristics, we comprehensively analyzed the provenance evolution from the 5th member of Nenjiang Formation to Mingshui Formation.
Results The detrital zircon ages exhibit age ranges across the formations: (1) The 5th member of Nenjiang Formation displays three predominant age ranges: 2994−1765 Ma, 281−281 Ma, and 125−79 Ma. (2) Sifangtai Formation exhibits four characteristic age ranges: 2797−1739 Ma, 462−455 Ma, 296−174 Ma, and 125−79 Ma. (3) Mingshui Formation shows three distinct age ranges: 2448−1792 Ma, 237−220 Ma, and 117−87 Ma.
Conclusions The provenance of the 5th member of Nenjiang Formation was primarily derived from the Zhangguangcai Range, along with the Jihei area to the east and the Liaoyuan area to the southeast of the Songliao Basin. Additionally, the eastern Lesser Xing’an Mountains to the northern Songliao Basin began contributing sediments to Sifangtai Formation. The provenance of Mingshui Formation was mainly sourced from the Zhangguangcai Range and the eastern Lesser Xing’an Mountains. The findings provide important insights for reconstructing Late Cretaceous paleogeography and understanding the tectonic evolution of Daqing placanticline.
下载: