Reply to comment by P. Duval and M. Montagnat on “Superplastic deformation of ice: Experimental observations”
Reply to comment by P. Duval and M. Montagnat on “Superplastic deformation of ice: Experimental observations”
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回复 P. Duval 和 M. Montagnat 关于“冰的超塑性变形：实验观察”的评论
DOI：
10.1029/2002jb001842
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发表时间：
2002
影响因子：
--
通讯作者：
D. Kohlstedt
中科院分区：
文献类型：
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作者：
D. Goldsby;D. Kohlstedt
[1]在最近的一篇论文中，我们报告了冰的流变特性的详细实验研究结果[Goldsby和Kohlstedt，2001]。我们的调查的创新方面之一是使用细晶粒的样品，使我们能够探索变形不仅由晶粒尺寸不敏感的机制，涉及晶粒基体位错过程，但也由晶粒尺寸敏感的流动机制，涉及晶界滑动（GBS）。在我们的研究中，一个令人兴奋的发现是一个广泛的蠕变制度，其中GBS大大有助于冰的流动。最重要的是，这种变形制度，其中基底滑移是由GBS容纳，在我们的论文中被称为“超塑性流动”制度，支配着在冰川，冰盖和冰冷的行星内部发现的温度，粒度和应力条件的广泛范围内的冰的流动。[2]在他们对我们的论文的评论中，Duval和Montagnat [2002]重复了他们以前提出的反对意见[Montagnat和Duval，2000]，反对我们关于超塑性变形控制冰川和冰盖流动的结论。他们断言“GBS作为一种重要的蠕变机制与冰盖中结构和微观结构发展的观察不相容。特别强调的是晶界迁移作为冰川冰中恢复过程的作用。然后，他们继续认为，基底滑移容纳晶界迁移（GBM），而不是GBS是占主导地位的变形机制在冰。[3]本文推广了Goldsby和Kohlstedt [1997]和Goldsby和Kohlstedt [2001]的结果，进一步证明了GBS是天然冰体中一个非常重要的变形过程。我们的推理是基于三点：（1）从大型天然冰体样品的微观结构报告是非常相似的，在超塑性流动状态下，在实验室中变形的样品中观察到的。(2)我们的冰本构方程与冰川和冰盖现场测量确定的流动行为非常一致。(3)与Montagnat和Duval [2000]以及Duval和Montagnat [2001]的断言相反，在我们的论文中描述的超塑性状态下，组构发展与变形完全相容。此外，我们注意到，虽然GBM与动态重结晶是一个重要的恢复机制，在冰，它不是一个变形机制，因此不能容纳基底滑移。
[1] In a recent paper, we reported the results of a detailed experimental investigation of the rheological properties of ice [Goldsby and Kohlstedt, 2001]. One of the innovative aspects of our investigation was the use of fine-grained samples that enabled us to explore deformation not only by grain-size insensitive mechanisms involving grain matrix dislocation processes but also by grain-size sensitive flow mechanisms involving grain boundary sliding (GBS). An exciting discovery in our research was an extensive creep regime in which GBS contributes substantially to the flow of ice. Most importantly, this deformation regime in which basal slip is accommodated by GBS, referred to in our paper as the ‘‘superplastic flow’’ regime, governs the flow of ice over a wide range of temperature, grain size and stress conditions found in glaciers, ice sheets and icy planetary interiors. [2] In their comment on our paper, Duval and Montagnat [2002] repeat the objection that they had raised previously [Montagnat and Duval, 2000] concerning our conclusion that superplastic deformation controls the flow of glaciers and ice sheets. They assert ‘‘that GBS as a significant creep mechanism is not compatible with observations on the development of fabrics and microstructures in ice sheets. Special emphasis is placed [instead] on the role of grain boundary migration as a recovery process in glacier ice.’’ They then continue by arguing that basal slip accommodated by grain boundary migration (GBM) rather than by GBS is the dominant deformation mechanism in ice. [3] In this reply, we extend the results presented in detail by Goldsby and Kohlstedt [1997] and Goldsby and Kohlstedt [2001] to further demonstrate that GBS is a very important deformation process in natural ice bodies. Our reasoning is based on three points: (1) The microstructures reported for samples from large natural ice bodies are remarkably similar to those observed in samples deformed in the laboratory in the superplastic flow regime. (2) Our constitutive equation for ice is in excellent agreement with the flow behavior determined from field measurements on glaciers and ice sheets. (3) Contrary to the assertion of Montagnat and Duval [2000] and Duval and Montagnat [2001], fabric development is fully compatible with deformation in the superplastic regime described in our paper. In addition, we note that, while GBM associated with dynamic recrystallization is an important recovery mechanism in ice, it is not a deformation mechanism and hence cannot accommodate basal slip.