摘要： 浊流作为向深水环境输送泥沙、有机碳等陆源碎屑物质的主要沉积过程,具有极强的沉积物输送和破坏能力。传统浊流沉积模式主要考虑其在平坦深水区的沉积过程; 但实际上,浊流所沉积的陆坡和各类构造盆地往往具有复杂的地貌特征。得益于大量的野外露头、数值与物理模拟和原位观测技术,浊流对地貌的水动力响应机制已比较明确,主要包括反射、偏转、水跃等。但由于获取具体的浊流参数较为困难,而构造地貌又较为复杂,从理解浊流的微观水动力响应机制到预测各类构造区浊流的宏观沉积分布仍存在着较大的鸿沟。以褶皱为例,浊流对多种类型复杂构造地貌的具体响应仍以各类沉积模式为主,集相似性与差异性为一体。在褶皱后缘等地貌的相对高点,浊流重力势能增加,浊流反射回流并在上游方向堆积沉积物; 在褶皱前缘等地貌的相对低点,浊流重力势能减小,浊流发生水跃并在下游方向堆积沉积物。同时,由于不同地貌的差异,浊流的沉积特征又有不同。尽管取得了相当的进展,当前研究仍以定性—半定量方法研究静态、单一构造地貌下的简单沉积模式为主,未来可以综合构造与沉积的视角,使用原位观测、模拟、实例解剖等定量方法综合研究相关问题。

关键词: 浊流, 深水沉积, 构造地貌, 水动力响应, 沉积物分布

Abstract: As one of the main sedimentary processes on Earth,turbidity current is responsible for transporting significant amounts of terrigenous sediments,such as mud,sand and organic carbon,into deep water environments. Traditional depositional models of turbidite systems mainly focus on deep-water areas with planar topography. However,slope areas and various tectonic basins hosting turbidite sedimentation often have complex topographic characteristics. Recent studies of turbidite systems based on outcrop observations,numerical and physical simulations as well as in-situ monitoring,have revealed the hydraulic responses of turbidity current to complex topography,namely flow reflection,deflection and hydraulic jump. However,due to the difficulties of acquiring hydraulic parameters of turbidity current,and the topographic complexities of various structures,a gap still remains between our understanding of the hydraulic response of turbidity current to local topographies and large-scale sediment distribution patterns in structurally-controlled basins. Thus,the studies of turbidity current responses to various topographic settings are still largely model driven,with both similarities and variations present among different models. Taking folding topography as an example,at topographic highs,the gravitational potential energy of turbidity current tends to increase,and the turbidity current reflects and accumulates sediments in the upstream direction;while at a topographic low,gravitational potential energy of turbidity current tends to decrease and the turbidity current experiences hydraulic jumps and drop sediments in the downstream direction. In other cases,due to topographic variations,the sedimentary characteristics of turbidites vary in different tectonic settings. In summary,although significant progress has been made on understanding turbidity current responses to structurally-controlled topography,most studies are still qualitative and semi-quantitative in nature with static or oversimplified topography. Future studies,especially case anatomy combined with quantitative methods,such as in-situ monitoring and simulation,are imperative to enhance our understanding of the topic.

Key words: turbidity current, deep-water sediments, structurally-controlled topography, hydrodynamic response, sediment dispersal

中图分类号: 

• P512.2