The application of microtextural and heavy mineral analysis to discriminate between storm and tsunami deposits
The application of microtextural and heavy mineral analysis to discriminate between storm and tsunami deposits
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DOI：
10.1144/sp456.7
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发表时间：
2017-02
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影响因子：
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通讯作者：
P. Costa;G. Gelfenbaum;S. Dawson;S. L. Selle;F. Milne;J. Cascalho;C. Lira;C. Andrade;M. C. Freitas;B. Jaffe
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作者：
P. Costa;G. Gelfenbaum;S. Dawson;S. L. Selle;F. Milne;J. Cascalho;C. Lira;C. Andrade;M. C. Freitas;B. Jaffe
摘要最近的工作已应用显微结构和重矿物分析桑迪和海啸沉积物从葡萄牙，苏格兰，印度尼西亚和美国。我们研究了石英颗粒和重矿物成分的显微结构图像（扫描电子显微镜）的解释。我们认为不同的年表和来源（公元1755年里斯本和2004年印度洋海啸，2005年1月11日在苏格兰的大风暴，飓风桑迪在2012年），影响对比鲜明的沿海和内陆地区设置不同的区域海洋条件的洪水事件。对风暴和海啸沉积物与潜在源沉积物（冲积物、海滩、沙丘和近岸沉积物）进行了沿着检查，以确定物源。结果表明，海啸沉积物通常表现出显着的粒度，显微结构和重矿物的空间变化。风暴沉积物的变化较小，特别是在垂直剖面上。海啸和风暴石英颗粒有更多的撞击痕迹和新鲜的表面相比，潜在的源材料。此外，在所研究的情况下，海啸样本的新鲜表面比风暴沉积物少。重矿物组合通常是特定地点的。重矿物的浓度在海啸发生单元中向上降低，而风暴沉积物显示出重矿物的循环浓度，这反映在沉积物中宏观观察到的层状结构中。
Abstract Recent work has applied microtextural and heavy mineral analyses to sandy storm and tsunami deposits from Portugal, Scotland, Indonesia and the USA. We looked at the interpretation of microtextural imagery (scanning electron microscopy) of quartz grains and heavy mineral compositions. We consider inundation events of different chronologies and sources (the AD 1755 Lisbon and 2004 Indian Ocean tsunamis, the Great Storm of 11 January 2005 in Scotland, and Hurricane Sandy in 2012) that affected contrasting coastal and hinterland settings with different regional oceanographic conditions. Storm and tsunami deposits were examined along with potential source sediments (alluvial, beach, dune and nearshore sediments) to determine provenance. Results suggest that tsunami deposits typically exhibit a significant spatial variation in grain sizes, microtextures and heavy minerals. Storm deposits show less variability, especially in vertical profiles. Tsunami and storm quartz grains had more percussion marks and fresh surfaces compared to potential source material. Moreover, in the studied cases, tsunami samples had fewer fresh surfaces than storm deposits. Heavy mineral assemblages are typically site-specific. The concentration of heavy minerals decreases upwards in tsunamigenic units, whereas storm sediments show cyclic concentrations of heavy minerals, reflected in the laminations observed macroscopically in the deposits.