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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Prograded foredunes ofWestern Australia's macrotidal coast - implications for Holocene sea- level change and high- energy wave impacts
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Prograded foredunes ofWestern Australia's macrotidal coast - implications for Holocene sea- level change and high- energy wave impacts

机译：西澳大利亚州大潮汐海岸的先进技术-对全新世海平面变化和高能波影响的影响

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The Holocene evolution of the Canning Coast of Western Australia has largely been overlooked so far mainly due to its remoteness and low population density. We report on new data from a sequence of foredunes inside the macro-tidal Admiral Bay, 110km southwest of Broome. Based on sediment cores, differential global positioning system (dGPS)-based elevation transects, and stratigraphical analyses on outcrops of the relict foredunes, we aim at reconstructing Holocene coastal changes and relative sea levels (RSLs), as well as identifying and dating imprints of extreme-wave events. Sedimentary analyses comprise the documentation of bedding structures, foraminiferal content and macrofaunal remains, grain size distribution, and organic matter. The chronological framework is based on 26 carbon-14 accelerator mass spectrometry (C-14-AMS) datings. Marine flooding of the pre-Holocene surface landward of the 2.5km-wide foredune barriers occurred 7400-7200calbp, when mangroves colonized the area. After only 200-400 years, a high-energy inter-tidal environment established and prevailed until c. 4000calbp, before turning into the present supralittoral mudflat. During that time, coastal regression led to beach progradation and the formation of aligned foredunes. Drivers of progradation were a stable RSL or gradual RSL fall after the mid-Holocene and a positive sand budget. The foredunes overlie upper beach deposits located up to >2m above the present upper beach level and provide evidence for a higher mid-Holocene RSL. Discontinuous layers of coarse shells and sand are intercalated in the foredunes, indicating massive coastal flooding events. One such layer was traced over three dune ridges and dated to c. 1700-1550calbp. However, it seems that most tropical cyclones induce net erosion rather than deposition at aligned foredunes and thus, they are only suitable for reconstructing temporal variability if erosional features or sedimentation reliably tied to these events can be identified and dated accurately. Copyright (c) 2014 John Wiley & Sons, Ltd.
机译：迄今为止，西澳大利亚州的坎宁海岸的全新世演化主要由于其偏远和低人口密度而被广泛忽视。我们报告了布鲁姆西南110公里处的大潮汐海军上将湾内一系列前兆的新数据。基于沉积物核心，基于差分全球定位系统（dGPS）的高程样线以及对遗物前兆的露头进行地层分析，我们旨在重建全新世的沿海变化和相对海平面（RSL），以及识别和定年极端波浪事件。沉积物分析包括层理结构，有孔虫含量和大型动物遗骸，粒度分布和有机物的记录。时间框架基于26个碳14加速器质谱（C-14-AMS）日期。当红树林在该地区前，全新世前地表2.5公里宽的前堡屏障向内的海洋洪水发生了7400-7200calbp。仅在200-400年后，便建立了高能潮间环境并盛行至c。 4000calbp，然后变成目前的上颌上滩。在这段时间里，沿海地区的退化导致了海滩的升级，并形成了前后一致的前兆。渐进的驱动因素是全新世中期后稳定的RSL或逐渐的RSL下降以及正的砂土预算。这些前兆覆盖了位于目前海滩上层以上2m以上的海滩上沉积物，并提供了全新世中期RSL较高的证据。不连贯的粗壳和沙子层插在前兆中，表明发生了大规模的沿海洪水事件。在三个沙丘脊上追踪了一层这样的层，其日期为c。 1700-1550calbp。但是，似乎大多数热带气旋引起的是净侵蚀，而不是对齐的前兆，因此，如果能够准确识别和确定与这些事件可靠相关的侵蚀特征或沉积，它们仅适用于重建时间变异性。版权所有（c）2014 John Wiley＆Sons，Ltd.

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