Reaction-induced embrittlement of the lower continental crust
Reaction-induced embrittlement of the lower continental crust
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DOI：
10.1130/g45527.1
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发表时间：
2019-03-01
期刊：
影响因子：
5.8
通讯作者：
Schubnel, Alexandre
中科院分区：
文献类型：
--
作者：
Incel, Sarah;Labrousse, Loic;Schubnel, Alexandre
野外观测和地球物理数据揭示了脆性地震破坏和下大陆地壳榴辉岩化之间的因果联系。我们给出了榴辉岩相条件下富斜长石样品的实验变形结果，并量化了岩石流变学与榴辉岩化反应动力学之间的联系。无论是在没有反应的情况下，还是在榴辉化进程快于施加的应变速率时，变形都是延性的。然而，当反应速度相对较慢时，斜长石分解为纳米晶反应产物引发了脆化，突出表现为高声发射活性。榴辉岩相条件下流体诱导的斜长石分解是伴随着固体体积负变化的放热反应。这类似于已知的触发转换断层作用的其他矿物转换。我们证明，在反应速度比变形速度慢的情况下，矿物反应会导致脆性变形。
Field observations and geophysical data reveal a causal link between brittle seismic failure and eclogitization of the lower continental crust. We present results from experimental deformation of plagioclase-rich samples at eclogite-facies conditions and quantify the link between rock rheology and the kinetics of the eclogitization reactions. The deformation was ductile both in the absence of reaction and when the progress of eclogitization was fast compared to the imposed strain rate. However, when the reaction rate was relatively slow, the breakdown of plagioclase into nanocrystalline reaction products triggered embrittlement, highlighted by a high acoustic emission activity. Fluid-induced plagioclase breakdown under eclogite-facies conditions is an exothermic reaction accompanied by a negative change in solid volume. This is similar to other mineral transformations that are known to trigger transformational faulting. We demonstrate that mineral reactions lead to brittle deformation in situations where reaction rates are slow compared to the deformation rate.