Sedimentology of coastal chevron deposits - tsunamigenic versus aeolian origin

v形沉积体的起源，即所谓的chevrons，目前在讨论中存在争议。目前，“纹章”一词仅根据沉积物体的形态来定义，而不是根据其成因来定义。讨论了风成成因和冲击-海啸成因。在这项研究中，研究了美国西海岸和西澳大利亚海岸的沉积物，研究了形纹的沉积学和起源。探地雷达有助于探测内部交叉层理和土壤层位。确定的沉积年龄强调了构造的活跃迁移，因为年龄在搬运方向上更年轻。相反，海啸起源的沉积物体在输运方向和垂直序列内都应显示同时代。此外，海啸沉积物一般只显示少量的沉积构造（如级配）。单峰粒度分布（平均直径：0.11-0.25 mm）强调了风成成因，因为海啸沉积物应该更粗，分选更少。初步结果表明，扇形的起源是风成的。这一假设需要在接下来的一年中得到加强，因为它需要将雪佛龙沉积物与可能的物质来源（如海滩、河流和悬崖）进行比较。在这里，来自风暴波底以下水深的海洋微生物可以作为可能的海啸成因的指标。

The origin of v-shaped sediment bodies, so-called chevrons, is currently controversially discussed. The term chevron is presently only defined in terms of the morphology of the sediment body, but not in terms of its genesis. Both an aeolian and an impact-tsunami origin are discussed. In this study, the sedimentology and origin of chevrons is investigated, examining deposits from the US west coast and the coast of Western Australia. Ground-penetrating radar has helped to detect internal cross bedding and soil horizons. Determined depositional ages underline active migration of the structures since the ages are younger in transport direction. In contrast, sediment bodies of tsunami origin should exhibit contemporaneous ages both in transport direction and within vertical successions. Furthermore, tsunami sediments generally display only few sedimentary structures (e.g. grading). Unimodal grain-size distributions (mean diameter: 0.11-0.25 mm) underline an aeolian origin, since tsunami sediments should be coarser and less sorted. The preliminary results point to an aeolian origin of chevrons. This assumption needs to be strengthened during the continuation year by comparing the chevron sediment with possible material sources, such as beaches, rivers and cliffs. Here, marine microorganisms from water depths below storm wave base, may be used as indicator for a possible tsunamigenic origin.