This study uses 3D reflection seismic data to investigate how sediment gravity flows contribute to the evolution of the lower continental slope of the Myanmar margin that is part of the Bengal Fan, the largest deep-water fan system in the world. Seafloor and subseafloor data show large sediment wave fields that developed on both flanks of an extensive submarine canyon. The sediment waves exhibit asymmetric stoss and lee sides, wave lengths and heights of 850–3000 m and 25–70 m, respectively, and an upslope direction of migration. Seismic data reveals the presence of multiple fields of vertically stacked sediment waves, interbedded with units characterised by a chaotic seismic facies that accumulate mainly in the troughs of the sediment waves and can be tracked laterally to the adjacent canyons. According to their seismic facies, geometry, and internal architecture these chaotic units are interpreted as debrites. Seismic attributes extracted from different horizons indicate that the sediment waves are dominated by fine-grained sediment, while the debrites are probably associated with coarser-grained deposits. The debrites fill the troughs of the sediment waves, as well as the downstream portions of canyon thalweg, thus flattening the paleo-seafloor. The sediment waves are interpreted as cyclic steps formed by low-density turbidity currents flowing across the slope down to the basin floor, where the change in gradient favours the formation of hydraulic jumps and the transition from supercritical to subcritical flow conditions. A conceptual model for the sediment wave evolution was proposed for the study area, in the transitional environment on the lower slope, with low-density gravity flow deposits and high-density debris flow deposits alternatively accumulating on the major gravity flow conduits.

本研究使用 3D 反射地震数据来研究沉积物重力流如何促进缅甸边缘下大陆坡的演化，缅甸边缘是世界上最大的深水扇系统孟加拉扇的一部分。海底和海底数据显示了在广阔的海底峡谷两侧形成的大型沉积波场。沉积物波呈现不对称的抛物面和背风面，波长和高度分别为 850-3000 m 和 25-70 m，向上迁移方向。地震数据显示存在多个垂直堆积的沉积波场，其中夹杂着以混沌地震相为特征的单元，这些地震相主要积聚在沉积波槽中，可以横向追踪到相邻的峡谷。根据它们的地震相、几何形状，和内部建筑这些混乱的单位被解释为碎片。从不同层位提取的地震属性表明，沉积波以细粒沉积物为主，而碎屑可能与粗粒沉积物有关。碎屑填满了沉积波的波谷，以及峡谷 thalweg 的下游部分，从而使古海底变平。沉积波被解释为由低密度浊流穿过斜坡向下流到盆地底部形成的循环台阶，在那里梯度的变化有利于水跃的形成和从超临界到亚临界流动条件的过渡。提出了研究区在下坡过渡环境中沉积波演化的概念模型，