Exchangeable cation composition of the smectite-rich plate boundary fault at the Japan Trench
Exchangeable cation composition of the smectite-rich plate boundary fault at the Japan Trench
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日本海沟富含蒙皂石的板块边界断层的可交换阳离子组成
DOI：
10.1002/2016gl068283
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发表时间：
2016
影响因子：
5.2
通讯作者：
M. Conin
中科院分区：
文献类型：
--
作者：
Kameda;J.;C. Inaoi;M. Conin
为了更好地了解富含蒙皂石的断层带的物理化学过程，我们研究了综合大洋钻探计划第343次考察队从2011年东北冲地震（Mw9.0）的滑动带中回收的样品的可交换阳离子组成。化学分析表明，滑动带中可交换的Ca 2+和Mg 2+富集，而Na+贫乏。K+显示复杂的深度剖面，可能是由于K固定。基于流体化学数据，估算了Ca 2 +-Mg 2 +-Na+三元体系交换反应的表观选择性系数。结果表明，蒙脱石上的Na+到Mg 2+交换反应可能在滑动带中进行。对这一特征的一种解释是地震期间同震生热引发的反应的局部进展。考虑到蒙皂石泥的摩擦特性取决于可交换阳离子的组成，本研究中观察到的化学过程与含蒙皂石断层的物理方面密切相关。
To better understand physicochemical processes in smectite‐rich fault zones, we examined exchangeable cation composition of samples from the slip zone of the 2011 Tohoku‐oki earthquake (Mw9.0) recovered by the Integrated Ocean Drilling Program Expedition 343. Our chemical analyses revealed that the exchangeable Ca2+and Mg2+are enriched in the slip zone, while Na+is depleted. K+shows a complicated depth profile probably due to K fixation. Based on fluid chemistry data, we estimated apparent selectivity coefficients of exchange reactions in the ternary Ca2+‐Mg2+‐Na+system. The results suggest that the Na+to Mg2+exchange reaction on smectite might have progressed in the slip zone. One explanation for this feature is local progress of the reaction triggered by coseismic thermogenesis during the earthquake. Considering that the frictional property of smectite gouge is dependent on the exchangeable cation composition, chemical processes as observed in this study are intimately linked to physical aspect of smectite‐bearing faults.