Research on the depositional record of submarine fans and related turbidite systems has highlighted the importance of channel, lobe and levée–overbank architectural elements as fundamental building blocks. However, many of the characteristics and processes of deposits left by flows traversing those fans remain elusive, because flows seem to be able to go unconfined for long distances. Offshore southern California (USA), the La Jolla Canyon decreases in relief to become an approximately U-shaped channel across the basin floor of the San Diego Trough. The La Jolla Channel gradually loses confinement and transitions to a network of scours, some of which align to form incipient channels, and fields of bedforms. High-resolution seafloor topography, CHIRP seismic-reflection data, sediment cores and hydrodynamic flow analysis are used to explore these features. The focus is on two regions of bedforms: (i) a field of net-depositional, concentric bedforms across the eastern levée–overbank upstream from the terminus of the La Jolla Channel; and (ii) a linear train of more erosional bedforms approximating an incipient channel adjacent to the present mouth of the La Jolla Channel. These bedforms are interpreted to be among a class of upper-flow-regime bedforms called cyclic steps, which were formed by densimetric Froude supercritical turbidity currents that spilled out of the present La Jolla Channel. The high-resolution data for the La Jolla Fan provide valuable insights into the characteristics of supercritical bedforms likely common to distal submarine fans, as well as on sedimentary processes likely important for submarine fan growth into sedimentary basins. In particular, the pattern of evolution of the La Jolla Fan suggests that cyclic steps with wavelengths on the order of tens of metres to a few hundreds of metres could be fundamentally important for the evolution of the distal submarine fans with relatively low-relief main channels.

中文翻译：

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探索远端潜艇风扇的新的循环步骤

对海底风机和相关浊积系统沉积记录的研究突显了通道，波瓣和堤岸-高架建筑元素作为基本构件的重要性。但是，穿越这些风扇的气流留下的许多特性和沉积过程仍然难以捉摸，因为气流似乎能够不受限制地长距离传播。拉霍亚峡谷（California）位于美国加利福尼亚南部沿海，浮雕减少，成为横跨圣地亚哥海槽盆地底部的近似U形航道。拉霍亚河道逐渐失去局限，过渡到冲刷网络​​，其中一些冲刷形成初始冲刷通道和床形场。高分辨率海底地形，CHIRP地震反射数据，沉积物岩心和水动力流分析被用来探索这些特征。重点关注床形的两个区域：（i）横跨拉霍亚海峡总站上游的东部大堤-岸边的网状沉积，同心床形区域；（ii）具有更多侵蚀性地层的线性序列，近似于与拉霍亚河道目前的河口相邻的初始河道。这些床形被解释为属于一类称为循环阶跃的上流型床形，它们是由从当前拉霍亚河道溢出的密西弗劳德超临界浑浊流形成的。La Jolla Fan的高分辨率数据提供了宝贵的见解，以了解远距离潜艇爱好者可能会遇到的超临界床形的特征，以及可能对海底扇向沉积盆地生长很重要的沉积过程。特别地，拉霍亚扇的演化模式表明，波长在几十米到几百米量级的周期性阶梯对于具有相对较低浮雕主通道的远侧海底扇的演化可能至关重要。 。