Earth Science Frontiers ›› 2025, Vol. 32 ›› Issue (3): 168-182.DOI: 10.13745/j.esf.sf.2025.3.60

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The paleoenvironmental evolution since 0.78 Ma in Caohai, Guizhou: evidence from XRF core scanning

XU Yudi1,2(), LIU Chengshuai1,3, GAO Ting1,3,*(), LIU Yu1, YIN Runsheng1, SUN Lu4   

  1. 1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
    3. South China Agricultural University, College of Natural Resources and Environment, Guangzhou 510642, China
    4. East China University of Technology, School of Earth Sciences, Nanchang 330013, China
  • Received:2025-01-02 Revised:2025-03-04 Online:2025-03-25 Published:2025-04-20

Abstract:

The climate of the Yunnan-Guizhou Plateau is significantly influenced by diverse monsoon systems, displaying a complex pattern of climatic changes. This study investigates the relationship between local environmental changes and global climate dynamics using sediment core 2023CH(D) from Caohai Lake in Guizhou Province. Employing high-resolution X-ray fluorescence (XRF) scanning and paleomagnetic dating, combined with multivariate statistical analysis of magnetic susceptibility, grain size, and elemental data (including Al, Si, K, Ca, etc.), this research explores the paleoenvironmental evolution of the Caohai region since 0.78 Ma. The findings identify five climatic phases: 1) Stage I (0.78-0.66 Ma), where the local climate essentially mirrored global climatic changes; 2) Stage II (0.63-0.33 Ma), dominated by global climate patterns but significantly modulated by Earth’s obliquity and precession cycles; 3) Stage III (0.32-0.22 Ma), characterized by a relatively mild glacial climate with cool, humid conditions that substantially promoted carbonate leaching; 4) Stage IV (0.21-0.12 Ma), predominantly cold and dry, with initial and final phases experiencing slightly warmer and more humid conditions, reflecting precession cycles in the relative intensity of physical and chemical weathering; 5) Stage V (0.12-0.02 Ma), generally trending towards colder and drier conditions, yet characterized by rapid oscillations between cold-dry and warm-humid states on sub-orbital scales, with an increasing amplitude. The climatic evolution in Caohai is influenced by both orbital and sub-orbital cycles, with varying responses among different palaeoenvironmental proxies. Vegetation coverage, primarily controlled by the intensity of the Asian monsoon and global climate conditions, exhibits sensitivities to these cycles, while variations in the intensity of physical and chemical weathering and precipitation are more closely aligned with obliquity and precession cycles. The climatic fluctuations in the Caohai region have shown a trend towards increased frequency and extremity. Overall, the response of Caohai’s climate to global changes is notably complex, and the underlying mechanisms driving these changes require further investigation.

Key words: Yunnan-Guizhou plateau, lake sediment, XRF core scanning, elemental geochemistry, palaeoenvironmental evolution

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