Rare earth elements record past earthquakes on exhumed limestone fault planes
Rare earth elements record past earthquakes on exhumed limestone fault planes
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DOI：
10.1111/j.1365-3121.2010.00969.x
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发表时间：
2010-12
期刊：
影响因子：
2.4
通讯作者：
I. Manighetti;E. Boucher;C. Chauvel;A. Schlagenhauf;L. Benedetti
中科院分区：
文献类型：
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作者：
I. Manighetti;E. Boucher;C. Chauvel;A. Schlagenhauf;L. Benedetti
评估过去地震的时间和强度是古地震学中的一个持续挑战。在这里，我们展示了稀土元素(REE)浓度可以用来限制过去大地震的数量和滑动。我们关注世界上罕见的断层之一-意大利马格诺拉正断层-其全新世地震历史已被准确了解。我们分析了保存完好的地震出土断层陡坎地表沿线10m处的42个样品和埋藏在地下的断层面上提取的7个样品。我们发现，第一米的土壤污染了陡峭的岩石，产生了一个显著的稀土元素“峰值”。在出土的陡峭上也发现了类似的峰，位置与已知的过去断裂之间的过渡重合。我们得出结论，稀土元素峰位于古地面水平，是剥离陡坎的大地震的良好标志。
Evaluating the timing and size of past earthquakes is a constant challenge in palaeoseismology. Here, we show that rare earth element (REE) concentrations can be used to constrain the number and slips of major past earthquakes. We focus on one of the rare faults worldwide – the Magnola normal fault, Italy – whose Holocene earthquake history is precisely known. We analysed 42 samples from along the 10 m that form the surface of the well‐preserved seismically exhumed fault scarp and seven samples extracted from the fault plane section buried in the ground. We show that the first metre of soil contaminates the scarp rocks, producing a marked concentration ‘peak’ in REE. Similar peaks are recognized on the exhumed scarp, at positions that coincide with the transitions between the known past ruptures. We conclude that the REE peaks locate palaeo‐ground levels and are excellent markers for the large earthquakes that exhumed the scarp.