Abstract Potential tsunami inundation areas can be predicted by the distribution of paleo tsunami deposits on land, which are mainly composed of marine-derived sands and muds. These exotic sandy and muddy layers have been identified by multiple approaches. However, there still remain uncertainties regarding the sources and weathering trends over the long term, and other useful proxies need to be investigated to identify of tsunami deposits. We examined the geochemical signatures of modern tsunami deposits from the Pacific coast of northeast Japan (2011 Tohoku tsunami) and those paleo tsunami deposits taken from the Tohoku District (Jogan, ~1080 calibrated ages before present [cal BP] and Yayoi, ca. 2000 cal BP). A geochemical ternary diagram (Seawater-Rock-(As + Metals)) showed the weathering trends of tsunami deposits over approximately 2000 years in the Sendai plain in the Tohoku. In the tsunami layers from the Tohoku, the Na/Ti atomic ratios markedly increased to 23.4 with an average value of 19.3 ± 3.0 (Jogan and Yayoi tsunami deposits), which was clearly higher than those of other layers (soil deposits, 10.3 ± 3.5 on average). These results show that Na/Ti ratios and other geochemical proxies are useful indicators of marine incursions in our case, and may contribute to the detection of muddy tsunami deposits close to the limit of inundation.

中文翻译：

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一种识别海洋入侵的地球化学方法：对日本东北太平洋沿岸海啸地质学的影响

摘要 通过陆上古海啸沉积物的分布可以预测潜在的海啸淹没区，这些沉积物主要由海生砂和泥组成。这些奇特的沙质和泥质层已通过多种方法识别出来。然而，从长期来看，来源和风化趋势仍然存在不确定性，需要调查其他有用的替代物来识别海啸沉积物。我们研究了来自日本东北部太平洋沿岸的现代海啸沉积物（2011 年东北海啸）和取自东北地区的古海啸沉积物的地球化学特征（Jogan，约 1080 年之前的校准年龄 [cal BP] 和 Yayoi，约 2000 年）校准血压）。地球化学三元图（海水-岩石-（As + 金属））显示了东北仙台平原近 2000 年来海啸沉积物的风化趋势。在东北海啸层中，Na/Ti原子比显着增加至23.4，平均值为19.3±3.0（Jogan和Yayoi海啸沉积物），明显高于其他层（土壤沉积物，10.3±3.5）一般）。这些结果表明，在我们的案例中，Na/Ti 比率和其他地球化学指标是海洋入侵的有用指标，可能有助于检测接近淹没极限的泥质海啸沉积物。明显高于其他层（土壤沉积，平均 10.3 ± 3.5）。这些结果表明，在我们的案例中，Na/Ti 比率和其他地球化学指标是海洋入侵的有用指标，可能有助于检测接近淹没极限的泥质海啸沉积物。明显高于其他层（土壤沉积，平均 10.3 ± 3.5）。这些结果表明，在我们的案例中，Na/Ti 比率和其他地球化学指标是海洋入侵的有用指标，可能有助于检测接近淹没极限的泥质海啸沉积物。