Channels with a sinuous planform are common in both continental and deep-marine environments on Earth, and similarly in high-resolution images of the surface of Mars. Whereas common in rivers, continuous lateral channel migration and point-bar deposition appear to be much less common in the deep sea. In the bends of rivers, near-bed flow driving point bar growth results from a cross-flow superelevation of the water surface that sets up a lateral hydrostatic pressure gradient driving an inward-directed flow near the bed. However, in deep-marine systems the surface between the turbidity current and overlying ambient fluid sits well above the channel margins, and therefore precludes a similar lateral superelevation of the current top. Here it is argued that the cross-flow component is related to a density gradient that mimics the effect of the hydrostatic pressure gradient in rivers, and develops as coarse suspended particles that experience little uplift, and therefore negligible overspill, become concentrated along the outer bank. This condition develops best in a two-part suspension made up of a highly concentrated, unstratified basal plug of coarse sediment overlain sharply by a dilute cloud of much finer sediment—a density structure that differs from the more typical upward exponential decrease in density. The abundance of coarse and fine sand, but depletion in the intermediate grain size fraction, is related to transgressive shelf processes and its influence on sediment supplied to the system, and in turn, the flow structure of the current. It is under these seemingly uncommon granulometric conditions that continuous laterally migrating channels, and accordingly, riverine-like point-bar deposition, is most common in the deep sea.

中文翻译：

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横向增生的蜿蜒河道及其沉积物：深水边坡系统的Goldilocks

在地球的大陆和深海环境中，具有弯曲平面形状的通道都很常见，在火星表面的高分辨率图像中也是如此。尽管在河流中很常见，但在深海中连续的横向河道迁移和点状杆状沉积似乎要少得多。在河流的拐弯处，近床水流驱动点的增长是由于水面的横流超高而产生的，该水流建立了侧向静水压力梯度，从而驱动了靠近河床的向内流动。但是，在深海系统中，浊流和上覆的环境流体之间的表面位于通道边界上方，因此排除了电流顶部的类似横向超高。这里认为，横流分量与模拟河流中静水压力梯度作用的密度梯度有关，并发展为粗大的悬浮颗粒，几乎没有隆起，因此可以忽略的溢流，沿外岸集中。 。这种情况在由两部分组成的悬浮液中发展得最好，该悬浮液由高度浓缩的，未分层的粗大沉积物基底堵塞物所覆盖，而稀薄的沉积物则将稀薄的沉积物云雾覆盖得更加陡峭，密度结构不同于更典型的向上呈指数下降的密度。粗砂和细砂的丰富度，但中间粒度级分的减少，与海侵性陆架过程及其对输送给系统的沉积物的影响有关，进而与水流的流动结构有关。