Microstructure and fabric development in ice: Lessons learned from in situ experiments and implications for understanding rock evolution
Microstructure and fabric development in ice: Lessons learned from in situ experiments and implications for understanding rock evolution
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DOI：
10.1016/j.jsg.2013.05.006
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发表时间：
2014-04
影响因子：
3.1
通讯作者：
C. Wilson;M. Peternell;S. Piazolo;V. Luzin
中科院分区：
文献类型：
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作者：
C. Wilson;M. Peternell;S. Piazolo;V. Luzin
在这篇文章中，我们回顾了冰中微观结构和结构的演变。根据综述，我们通过考虑与富含石英的岩石相关的选定示例，展示了冰作为岩石类似物的潜在用途。我们对冰的可塑性的理解取得了进展，这些实验研究清楚地表明多晶冰的塑性变形最初是由基底滑移产生的。位错的相互作用对于冰稳态流动过程中涉及晶粒成核和晶界迁移的动态再结晶过程起着至关重要的作用。为了支持这篇综述，我们描述了多晶“标准”水冰和天然冰样品的变形，总结了涉及大块样品的其他实验，并使用原位面应变变形实验来说明微观结构与织物演化、流变响应和主导过程之间的联系。大多数陆地冰块在低剪切应力下会因颗粒尺寸不敏感的蠕变而变形，应力指数为 (n≤ 3)。然而，实验观察表明，产生微观结构和织物的塑性活动分布最初由硬化过程中的晶界迁移（初级蠕变）主导，随后是瞬态蠕变过程中的动态再结晶（次级蠕变），涉及新的晶粒成核，晶粒生长和成核的进一步循环导致接近稳态蠕变（第三级蠕变）。微观结构转变和推断的机制变化是应变能（即位错密度）局部和整体变化的函数，表面晶界能是次要的，静态退火的情况除外。由于冰的流变性与多晶石英的高温变形位错蠕变状态之间存在明显的对应关系，因此我们建议可以利用从冰变形中吸取的经验教训来解释多晶石英的变形。与石英不同，冰允许在接近自然应变率的情况下进行实验研究，并且现场实验提供了研究微观结构发展、流变学和主要过程识别之间动态联系的机会。
In this contribution we present a review of the evolution of microstructures and fabric in ice. Based on the review we show the potential use of ice as an analogue for rocks by considering selected examples that can be related to quartz-rich rocks. Advances in our understanding of the plasticity of ice have come from experimental investigations that clearly show that plastic deformation of polycrystalline ice is initially produced by basal slip. Interaction of dislocations play an essential role for dynamic recrystallization processes involving grain nucleation and grain-boundary migration during the steady-state flow of ice. To support this review we describe deformation in polycrystalline ‘standard’ water-ice and natural-ice samples, summarize other experiments involving bulk samples and usein situplane-strain deformation experiments to illustrate the link between microstructure and fabric evolution, rheological response and dominant processes. Most terrestrial ice masses deform at low shear stresses by grain-size-insensitive creep with a stress exponent (n≤ 3). However, from experimental observations it is shown that the distribution of plastic activity producing the microstructure and fabric is initially dominated by grain-boundary migration during hardening (primary creep), followed by dynamic recrystallization during transient creep (secondary creep) involving new grain nucleation, with further cycles of grain growth and nucleation resulting in near steady-state creep (tertiary creep). The microstructural transitions and inferred mechanism changes are a function of local and bulk variations in strain energy (i.e. dislocation densities) with surface grain-boundary energy being secondary, except in the case of static annealing. As there is a clear correspondence between the rheology of ice and the high-temperature deformation dislocation creep regime of polycrystalline quartz, we suggest that lessons learnt from ice deformation can be used to interpret polycrystalline quartz deformation. Different to quartz, ice allows experimental investigations at close to natural strain rate, and throughin-situexperiments offers the opportunity to study the dynamic link between microstructural development, rheology and the identification of the dominant processes.