Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (3): 80-99.DOI: 10.13745/j.esf.sf.2023.6.22

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Quantitative analysis of provenance in the Lower Cretaceous of the northwestern Ordos Basin

LIU Chiheng1(), LI Ziying1, HE Feng1, ZHANG Zilong1, LI Zhencheng4, LING Mingxing3, LIU Ruiping2   

  1. 1. CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology, Beijing 100029, China
    2. Analytical Laboratory of BRIUG, Beijing 100029, China
    3. State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China
    4. CNNC Geologic Party No.208, Baotou 014010, China
  • Received:2023-02-11 Revised:2023-05-28 Online:2024-05-25 Published:2024-05-25

Abstract:

The Lower Cretaceous represents a significant structural layer in the Ordos Basin, particularly notable for the emergence of sandstone-type uranium deposits in recent years. Understanding the source-sink dynamics during this period offers valuable insights into the tectonic-sedimentary processes triggered by the late Yanshanian orogeny in the western North China Craton, the paleoclimate transition, and the enrichment patterns of sandstone uranium deposits within the Ordos Basin. In this study, we conducted paleocurrent azimuth measurements and detrital zircon U-Pb dating across various strata of the Lower Cretaceous in the northwestern Ordos Basin. Furthermore, we refined the compilation approach for the zircon U-Pb age dataset in the potential provenance area surrounding the basin. Utilizing quantitative analyses, we assessed the detrital contributions from each provenance to the basin. Subsequently, the source-sink system of the Lower Cretaceous in the northwestern Ordos Basin was reconstructed. The results delineate the U-Pb ages of detrital zircons from the Lower Cretaceous into three primary groups: 1.79-1.64 Ga, 2.02-1.82 Ga, and 2.58-2.45 Ga, corresponding to Precambrian ages. Additionally, two major age groups of 336-257 Ma and 476-425 Ma signify Phanerozoic ages. Through quantitative provenance analysis, we identified the Yinshan, Langshan, Zhuozishan-Helanshan, and Alxa regions as collective sediment contributors to the study area, each with varying contribution ratios, indicating a diverse provenance supply. Our study suggests that during the Early Cretaceous, the Yinshan and Langshan regions primarily acted as provenance areas, supplying fluvial deposits to the basin’s interior. In contrast, the Alashan area transported sediments from the northern part of Zhuozishan and the Helanshan peak into the Ordos Basin through aeolian processes. This phenomenon led to the deposition of alternating eolian and fluvial formations in the study area during the Luohe-Lohandong period in the Early Cretaceous.

Key words: Ordos Basin, detrital zircon U-Pb age, provenance analysis, paleocurrent, sandstone-type uranium deposit, source-sink system

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