Localization and delocalization of deformation in a bimineralic material
Localization and delocalization of deformation in a bimineralic material
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双矿物材料变形的局域化和离域化
DOI：
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发表时间：
2015
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通讯作者：
J. Reber
中科院分区：
文献类型：
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作者：
S. Jammes;L. Lavier;J. Reber
我们研究如何本地化和离域变形发生在一个强斜长石和较弱的石英相组成的双矿物材料。我们进行数值、米级剪切实验，在实验中我们改变温度和两种矿物相的比例。三个微观力学变形场被确定根据在玩的矿物的力学行为（脆性或韧性时，两个阶段是在脆性或韧性制度，分别和半脆性时，一个阶段是在脆性和其他在韧性制度）。除了这些微观力学变形领域，我们确定了三种变形类型的本地化程度（I型：本地化剪切带，II型：本地化的剪切带，和III型：离域剪切带）。脆性变形领域中预计会出现I型。在半脆性区，可以观察到所有的变形类型取决于存在的弱相的量。在韧性场中，变形取决于两相之间的强度比。对于低强度比，总是观察到III型变形。对于高强度比，对于中等量的弱相，可以观察到II型变形。少量的弱相（<10%）逆转了强相的力学行为，并导致形成一个狭窄的闭合剪切带（II型），其中预期完全韧性（III型）行为。这突出了双矿物材料对于变形局部化和整体大规模变形过程的重要性。
We investigate how localization and delocalization of deformation occurs in a bimineralic material composed of a strong plagioclase and a weaker quartz phase. We perform numerical, meter‐scale shear experiments in which we vary the temperature and the ratio of the two mineral phases. Three micromechanical deformation fields are identified according to the mechanical behavior of the minerals at play (brittle or ductile when both phases are in the brittle or ductile regime, respectively, and semibrittle when one phase is in the brittle and the other in the ductile regime). Besides these micromechanical deformation fields, we identify three deformation types characterizing the degree of localization (type I: localized shear zone, type II: localized anastomosing shear zone, and type III: delocalized shear zone). Type I is expected in the brittle deformation field. In the semibrittle field, all deformation types can be observed depending on the amount of weak phase present. In the ductile field, deformation is dependent on the strength ratio between the two phases. For a low strength ratio, deformation of type III is always observed. For high‐strength ratios, deformation of type II can be observed for a moderate amount of weak phase. A small amount of weak phase (<10%) reverses the mechanical behavior of the strong phase and leads to the formation of a narrow anastomosing shear zone (type II) where fully ductile (type III) behavior is expected. This highlights the importance of a bimineralic material for the deformation localization and overall large‐scale deformation processes.