新西兰奥克兰理工大学Marta Ribó研究小组，报道了对海底峡谷冲刷事件期间重力流动力学的新见解。这一研究成果发表在2024年10月21日出版的国际学术期刊《地质学》上。

据悉，在罕见的高震级事件中，数百万吨的物质被冲刷穿过海底峡谷，将沿海沉积物运送到深海。然而，由于冲刷事件的破坏性和罕见性，与个别峡谷冲刷事件相关的观测具有挑战性。新西兰奥特罗亚洲凯库拉峡谷（Kaikōura）记录了在过去的十年中最大一次重力流的影响，2016年的Kaikōura地震（M_w7.8）调动了＞1 km³的沉积物。

本研究提供了新的高分辨率（<1 m）多波束数据，这些数据是由自主水下航行器（AUV）沿着Kaikōura峡谷轴线收集的，同时还提供了侧扫声纳和海底视频图像。数据集揭示了以前没有发现的广泛的侵蚀和沉积特征。研究人员在峡谷上部发现了侵蚀的基岩和深层侵蚀结构，包括线状沟槽和岩崩碎片（直径＞5米的巨砾）。该侵蚀区向峡谷下游过渡为粗粒状沉积层，包括旋回台阶和砾石波（平均波长250m，波高约20m），覆盖峡谷中下游。

研究结果强调，观测提供了高分辨率的现场证据，证明了(1)从泥石流到高密度浊流的流动转化；(2)在不频繁的高能峡谷冲刷事件中，横跨和向下弯曲的浊流中的流动动力学变化。这项研究为创造和塑造近岸基岩切割海底峡谷的过程提供了新的见解。

附：英文原文

Title: New insights on gravity flow dynamics during submarine canyon flushing events

Author: Marta Ribó, Joshu J. Mountjoy, Neil Mitchell, Sally J. Watson, Jasper J.L. Hoffmann, Susi Woelz

Issue&Volume: 2024-10-21

Abstract: Millions of tons of material are flushed through submarine canyons during infrequent high-magnitude events, transporting coastal sediment to the deep ocean. However, observations related to individual canyon flushing events are challenging due to the destructive nature and infrequency of flushing events. The impacts of one of the largest gravity flows in the past decade were documented in Kaikōura Canyon, AotearoaNew Zealand, where >1 km³ of sediment was mobilized by the 2016 CE Kaikōura earthquake (M_w 7.8). We present new high-resolution (<1 m) multibeam data collected with an autonomous underwater vehicle (AUV) along the Kaikōura Canyon axis, together with side-scan sonar and seafloor video imagery. These data sets reveal a wide range of erosional and depositional features that were not previously identified. Eroded bedrock and deep erosional structures are found in the upper canyon, including linear grooves, and rockfall debris (>5-m-diameter boulders). This erosional area transitions downcanyon to coarse-grained depositional bedforms, including cyclic steps and gravel waves (average wavelengths of 250 m and wave heights of ～20 m), covering the mid- and lower canyon. Our observations provide high-resolution field-based evidence of (1) flow transformation, from a debris flow to a high-density turbidity current; and (2) variations of flow dynamics within turbidity currents both across- and downcanyon, during an infrequent, high-energy canyon flushing event. This research offers new insights into the processes that create and shape nearshore bedrock-incising submarine canyons.

DOI: 10.1130/G52424.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52424.1/649415/New-insights-on-gravity-flow-dynamics-during