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<p>The northeastern margin of the Tibetan Plateau is characterized by intense tectonic activity and a highly variable climate, making it a high-incidence region for ancient landslide-dammed lakes in China. The Guide Basin, located on the northeastern margin of the Tibetan Plateau, hosts the Ashigong landslide, a typical ancient landslide situated on the right bank of the Garang River. However, the activity phases and evolutionary history of this landslide-dammed lake remain poorly understood. This study conducts detailed field investigations, integrating optically stimulated luminescence (OSL) dating, UAV-based three-dimensional modeling, and GIS analysis, to establish the developmental phases and chronology of the Ashigong landslide-dammed lake, and to explore its formation and evolutionary mechanisms. The results indicate that the Ashigong landslide is a two-phase composite landslide, with both phases blocking the Garang River and forming dammed lakes of varying sizes. The first-phase landslide has a volume of 5.88 × 10⁸ m³ and is classified as a giant bedding-plane landslide. The dammed lake formed during this phase had an estimated volume of approximately 3.1 × 10⁷ m³ and persisted from roughly 40 to 22 ka, indirectly constraining the formation of the first-phase landslide to around 40&#xa0;ka. The second-phase landslide has a volume of 0.42 × 10⁸ m³ and is classified as a very large landslide. The dammed lake formed during this phase had a volume of approximately 7.17 × 10⁶ m³ and existed from around 21 to 14&#xa0;ka, indirectly constraining the formation of the second-phase landslide to approximately 21&#xa0;ka. Considering the regional tectonic context, earthquakes are interpreted as one of the primary triggers of the Ashigong composite landslide, while long-term climatic factors, such as rainfall infiltration, progressively weakened slope stability. The breaching of the dammed lake likely occurred on a weakened dam foundation, triggered by events such as intense rainfall or seasonal floods that enhanced hydraulic forces. The formation and disappearance of the dammed lakes not only affected the stability of slopes on both riverbanks but also intensified regional erosion, collectively reshaping the geomorphology of the watershed. This study not only clarifies the developmental history and activity phases of the landslide but also provides valuable insights for research on regional evolution and paleo-earthquake events.</p>

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Formation process of the Ashigong ancient landslide-dammed lake in Guide Basin: impact on geomorphological evolution

  • 期刊论文

  • 发表日期：

    2026年6月30日

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  • Zuopeng Wang,
  • Yezi Quan,
  • Jianbing Peng,
  • Mingdong Zang,
  • Changming Lu,
  • Ruihao Ning

摘要

The northeastern margin of the Tibetan Plateau is characterized by intense tectonic activity and a highly variable climate, making it a high-incidence region for ancient landslide-dammed lakes in China. The Guide Basin, located on the northeastern margin of the Tibetan Plateau, hosts the Ashigong landslide, a typical ancient landslide situated on the right bank of the Garang River. However, the activity phases and evolutionary history of this landslide-dammed lake remain poorly understood. This study conducts detailed field investigations, integrating optically stimulated luminescence (OSL) dating, UAV-based three-dimensional modeling, and GIS analysis, to establish the developmental phases and chronology of the Ashigong landslide-dammed lake, and to explore its formation and evolutionary mechanisms. The results indicate that the Ashigong landslide is a two-phase composite landslide, with both phases blocking the Garang River and forming dammed lakes of varying sizes. The first-phase landslide has a volume of 5.88 × 10⁸ m³ and is classified as a giant bedding-plane landslide. The dammed lake formed during this phase had an estimated volume of approximately 3.1 × 10⁷ m³ and persisted from roughly 40 to 22 ka, indirectly constraining the formation of the first-phase landslide to around 40 ka. The second-phase landslide has a volume of 0.42 × 10⁸ m³ and is classified as a very large landslide. The dammed lake formed during this phase had a volume of approximately 7.17 × 10⁶ m³ and existed from around 21 to 14 ka, indirectly constraining the formation of the second-phase landslide to approximately 21 ka. Considering the regional tectonic context, earthquakes are interpreted as one of the primary triggers of the Ashigong composite landslide, while long-term climatic factors, such as rainfall infiltration, progressively weakened slope stability. The breaching of the dammed lake likely occurred on a weakened dam foundation, triggered by events such as intense rainfall or seasonal floods that enhanced hydraulic forces. The formation and disappearance of the dammed lakes not only affected the stability of slopes on both riverbanks but also intensified regional erosion, collectively reshaping the geomorphology of the watershed. This study not only clarifies the developmental history and activity phases of the landslide but also provides valuable insights for research on regional evolution and paleo-earthquake events.