Strain localization bands in fine-grained aggregates of germanate olivine and pyroxene deformed by a Griggs type apparatus
Strain localization bands in fine-grained aggregates of germanate olivine and pyroxene deformed by a Griggs type apparatus
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DOI：
10.1016/j.ijrmms.2021.104812
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发表时间：
2021-08
影响因子：
7.2
通讯作者：
S. Sawa;J. Muto;N. Miyajima;R. Shiraishi;M. Kido;H. Nagahama
中科院分区：
文献类型：
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作者：
S. Sawa;J. Muto;N. Miyajima;R. Shiraishi;M. Kido;H. Nagahama
在从脆性断裂到碎裂（或韧性）流动的过渡应力状态下，在自然和实验变形的多孔岩石中经常观察到应变局部化带。在以往的研究中使用的岩石样本大多是天然多孔的粗砂岩。同时，采用粉末中产生的细粒聚集体作为初始试样进行高压同轴变形实验。一般来说，这些骨料的压实烧结是在实验之前进行的。在实验（冷压）过程中，未对粉末进行高压低温压实的同轴实验。这种烧结过程中的应力状态接近于脆性断裂向碎裂流的过渡状态，因此，在实验室实验中，有可能在变形的冷压阶段形成压实带，这是一种应变局部化带。利用Griggs型装置对孔隙度约为30%的细粒锗酸橄榄石和辉石粉体进行了冷压实验。实验结果表明，在压实和烧结试样中形成了压实带。显微组织分析表明，在压实过程中，具有高位错密度的晶粒在剪切应变集中的情况下发生旋转和压碎。在压实结束时，颗粒尺寸变小，带由细粒材料制成。
Strain localization bands are often observed in natural and experimentally deformed porous rocks in stress state of the transitional regime, from brittle faulting to cataclastic (or ductile) flow. The rock samples used in most of the previous studies were natural porous coarse sandstones. Meanwhile, fine-grained aggregates originating from powders were used as an initial sample for high-pressure coaxial deformation experiments. Generally, compaction for sintering these aggregates were performed before the experiments. No coaxial experiments have been performed the compaction of the powder under high pressure and low temperature during experiments (cold pressing). This stress state during sintering is close to the transitional regime from brittle faulting to cataclastic flow, hence, there is a possibility that compaction bands which are a type of strain localization bands may form at the cold-pressing stage of deformation in laboratory experiments. We conducted cold pressing experiments on the powder of fine-grained germanate olivine and pyroxene with approximately 30% porosity using a Griggs type apparatus. The experiments reveal that compaction bands form in the compacted and sintered sample. Microstructural analysis revealed that grains with a high dislocation density rotate and crush with shear strain concentration during compaction. At the end of the compaction, the grain size becomes small and bands are made of fine-grained material.