Earthquake impact on iron isotope signatures recorded in mineral spring water
Earthquake impact on iron isotope signatures recorded in mineral spring water
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DOI：
10.1002/2016jb013408
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发表时间：
2016-12
期刊：
影响因子：
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通讯作者：
J. Schuessler;H. Kämpf;U. Koch;M. Alawi
中科院分区：
文献类型：
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作者：
J. Schuessler;H. Kämpf;U. Koch;M. Alawi
我们调查了溶解Fe的Wettinquelle矿泉水（巴特布兰巴赫，德国）的铁同位素签名的时间序列采样覆盖地震活跃期附近的构造活动的埃格裂谷系统在中欧。我们的目的是测试铁同位素是否能追踪深部裂隙花岗岩含水层的流体/岩石相互作用中地震引起的非生物和生物变化。泉水溶解态Fe同位素特征与花岗岩源特征（δ 56 Fe = +0.09‰）明显不同。特别是在2000年的一次强震群（ML > 3级）前后，水δ 56 Fe值非常稳定（-0.01 ± 0.11‰，2SD，n = 4），而水中O2和H2浓度降低，溶解Fe含量增加。2001 ~ 2003年期间，又观测到δ 56 Fe值下降到-0.3 ‰的低值事件，并伴有间歇性地震（1 < ML < 3.2）。观测结果表明，构造强迫和铁同位素响应之间的时间滞后。非生物流体/岩石相互作用和铁利用细菌鉴定矿泉水中的铁同位素分馏的作用进行了讨论。我们解释经常发生的变化，同位素轻的值由铁溶解从深部花岗岩和混合物的同位素轻铁产生的非生物和生物过程的复杂组合在含水层中运行时，群震事件的干扰相结合。我们提出了一个概念模型的情况下，地震触发的地球化学过程的变化。
We investigated the iron isotope signatures of dissolved Fe in the water of the Wettinquelle mineral spring (Bad Brambach, Germany) by time series sampling covering seismically active periods related to tectonic activity near the Eger Rift system in central Europe. Our objective was to test whether Fe isotopes trace earthquake‐induced abiotic and biotic changes in the fluid/rock interaction of the deep, fissured, granitic aquifer. We found that the dissolved Fe isotope signatures in spring water are distinct from the granitic source signature (δ56Fe = +0.09‰). Particularly, we discovered that water δ56Fe values are remarkably stable (−0.01 ± 0.11‰, 2SD, n = 4) before and during a strong seismic swarm period in 2000 (local magnitudes ML > 3), while O2 and H2 concentrations in water decrease and dissolved Fe content increases. Later, recurring events of lower δ56Fe values down to −0.3‰ are observed in the period from 2001 to 2003 with intermittent seismic events (1 < ML < 3.2). The observations indicate a time lag between tectonic forcing and Fe isotope response. The role of abiotic fluid/rock interaction and Fe‐utilizing bacteria identified in the mineral spring water on Fe isotope fractionation is discussed. We explain recurring changes toward isotopically lighter values by a combination of Fe dissolution from deep granite and admixture of isotopically light Fe generated by a complex combination of abiotic and biotic processes operating in the aquifer when disturbed by swarm earthquakes events. We propose a conceptual model scenario of earthquake‐triggered changes in biogeochemical processes.