Comparison of brittle- and viscous creep in quartzites: Implications for semi-brittle flow of rocks
Comparison of brittle- and viscous creep in quartzites: Implications for semi-brittle flow of rocks
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DOI：
10.1016/j.jsg.2018.05.022
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发表时间：
2018-08
影响因子：
3.1
通讯作者：
J. Reber;M. Peč
中科院分区：
文献类型：
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作者：
J. Reber;M. Peč
脆性和粘性变形过程的共存和相互作用有助于地壳的综合强度，并导致从地震到蠕变的广泛能量释放机制。在这里，我们比较了由脆性蠕变、湿位错幂律蠕变和溶解沉淀蠕变引起的富含石英岩石变形的流动定律。我们从理论上研究了当脆性过程和粘性过程都对变形产生显着贡献时的条件，前提是所有过程独立且并行地起作用。利用富含石英岩石变形实验的综合数据集，我们发现变形机制之间的转变强烈依赖于输入变量，例如初始缺陷尺寸和晶粒尺寸。这种转变可能会突然发生，或者在不同应力下发生数百兆帕，在恒定应变率下发生数百开氏度。这种转变强烈依赖于晶粒尺寸和围压。这项工作的局限性首先是所有三种流动定律都很难受到与比较相关条件的实验数据的约束。其次，需要新的实验来填补高温和低温变形实验之间的知识空白，并推导低温塑性和高温脆性蠕变的定量流动定律。
The co-existence and interaction between brittle and viscous deformation processes contributes to the integrated strength of the crust and results in a wide range of energy-release mechanisms ranging from earthquakes to creep. Here, we compare flow laws derived for quartz-rich rocks deforming by brittle creep, wet dislocation power-law creep and dissolution-precipitation creep. We investigate theoretically the conditions when both brittle and viscous processes contribute significantly to deformation provided that all processes act independently and in parallel. Utilizing a comprehensive data set for deformation experiments in quartz-rich rocks, we find that the transition between deformation mechanisms is strongly dependent on input variables such as initial flaw size and grain size. The transition can occur abruptly or over hundreds of MPa in differential stress and hundreds of degrees Kelvin at a constant strain rate. The transition is strongly dependent on grain-size and confining pressure. Limitations to this work are first that all three flow laws are poorly constrained by experimental data for conditions relevant for the comparison. Secondly, a need exists for new experiments to infill the knowledge gaps between high-temperature and low-temperature deformation experiments and deriving quantitative flow laws for low-temperature plasticity and high-temperature brittle creep.