Sedimentology of coastal chevron deposits - tsunamigenic versus aeolian origin

v形沉积体，即所谓的人字形沉积体的起源，目前在讨论中存在争议。目前，人字形一词仅根据沉积体的形态来定义，而不是根据其成因来定义。风成和冲击海啸的起源进行了讨论。在这项研究中，沉积学和起源的人字形的调查，检查存款从美国西海岸和西澳大利亚州海岸。探地雷达有助于探测内部交错层理和土层。确定的沉积年龄强调积极迁移的结构，因为年龄是年轻的运输方向。与此相反，海啸起源的沉积体应表现出同期的年龄在运输方向和垂直序列内。此外，海啸沉积物通常只显示很少的沉积结构（例如分级）。单峰粒度分布（平均直径：0.11-0.25毫米）强调风成成因，因为海啸沉积物应该是粗糙的，少排序。初步结果表明，人字形的风成成因。这一假设需要在连续一年中通过比较人字形沉积物与海滩、河流和悬崖等可能的物质来源来加强。在这里，海洋微生物从水深处低于风暴波基地，可作为一个可能的海啸起源的指标。

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.