海底滑坡顶界面地貌形态对浊流的影响机制
- 收稿日期:
2024-08-29
- 网络出版日期:
2024-11-26
摘要: 【目的】大型海底滑坡的失稳过程可以导致数千平方公里的海底发生变形和破坏，搬运数百—数千立方千米海底沉积物。这一过程极大地重塑了陆架—陆坡区的海底地形地貌，并对后续的海底沉积过程产生深远影响。【方法】通过多波束水深数据和地震反射数据定性描述不同大型海底滑坡的顶界面形态特征，以及定量刻画海底滑坡顶界面的面积和体积等关键几何参数，基于海底滑坡顶界面伴生地貌的规模，形态特征和形成机制等因素，将海底滑坡顶界面伴生地貌形态划分为头部排空区、内部断层体系伴生局部负向空间和内部块体伴生局部负向空间三类，并分别探讨这三类负向空间对后续浊流体系的影响机制。【结果】首先，海底滑坡头部排空区通常伴生数百至数千平方公里的负向空间，在陆缘沉积物运输过程中发挥“漏斗”作用，能够有效捕捉和汇集后续浊流，同时提高砾石、粗砂等粗粒碎屑沉积物的运输效率。其次，海底滑坡内部断层体系伴生的条带状负向空间与海底滑坡内部变形块体伴生的不规则负向空间能够调控后续浊流体系的沉积动力过程，例如约束浊流流向、增强浊流侵蚀强度以及迫使浊流水道决口等。最后，大型海底滑坡顶界面伴生负向空间可能产生协同效应，在数百万年的时间尺度内影响沉积盆地的充填演化过程和盆地沉积中心的分布位置。【结论】通过调研海底滑坡顶界面不同地貌形态及其对后续浊流沉积动力过程的控制作用，可为厘清陆缘沉积物的运输过程、查明深海沉积盆地富砂储层的分布，以及预测灾害性浊流的发育范围等提供关键的地质信息。
Top Surface Geomorphology of Submarine Landslides and Its Impact on Turbidity Currents
- Received Date:
2024-08-29
- Available Online:
2024-11-26
Abstract: [Objective] The catastrophic failure of large submarine landslides can result in the deformation and destruction of thousands of square kilometers of seafloor, transporting hundreds to thousands of cubic kilometers of submarine sediments. This process dramatically reconstructs the seafloor topography of the continental shelf-slope region and has a profound impact on subsequent submarine sedimentation processes. [Methods] The topographic features of different large submarine landslides were qualitatively described using multibeam bathymetric and seismic reflection data, and the key geometric parameters of the submarine landslide top surface, such as area and volume, were quantitatively characterized. Based on the scale, morphological features, and formation mechanisms of the associated reliefs on the submarine landslide top surface, these landslides were separated into three categories: head evacuation zone, locally negative accommodation associated with internal fault systems, and locally negative accommodation associated with internal deformation blocks. The mechanisms of the three types of negative accommodation on the subsequent turbidity current system are then discussed separately. [Results] Firstly, the head evacuation zone is typically associated with hundreds to thousands of square kilometers of negative accommodation, which acts as a "funnel" during sediment transport along the continental margin, effectively capturing and concentrating subsequent turbidity currents while enhancing the transport efficiency of gravel and coarse sand and playing a crucial role in the accumulation of marine organic matter. Secondly, the striped negative accommodation associated with internal fault systems and the irregular negative accommodation associated with internal deformation blocks can regulate the sedimentation dynamics of subsequent turbidity currents, such as constraining flow direction, enhancing erosion intensity, and forcing channels to avulse. Finally, the negative accommodations associated with the submarine landslide top surface may produce synergistic effects, influencing the sediment filling and evolution of sedimentary basins and the distribution of sedimentary centers over millions of years. [Conclusion] The investigation of the morphological characteristics of submarine landslide top surfaces and their controlling effects on the subsequent turbidity currents sedimentary dynamic process can provide key geological information for clarifying the transport process of marginal sediments, identifying the distribution of sand-rich reservoirs in deep-sea sedimentary basins, and predicting the development range of catastrophic turbidity currents.
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