Deformation of Granitic Rocks: Experimental Studies and Natural Examples
Deformation of Granitic Rocks: Experimental Studies and Natural Examples
复制标题
DOI：
10.2138/gsrmg.51.1.51
复制
发表时间：
2002
影响因子：
--
通讯作者：
J. Tullis
中科院分区：
文献类型：
--
作者：
J. Tullis
地壳变形本质上是复杂的，因为地壳在各种尺度上都是不均匀和各向异性的。我们在理解上的进步来自于实地观察、实验室实验和理论模型的结合。将所有这些调查联系起来的必然是对过程的关注。晶体塑性(位错蠕变)是几种晶级变形过程或机制中的一种；每个过程在一定范围的地壳条件下占主导地位，具有特定形式的流动规律，并产生一组特有的微观结构。表征不同矿物在一系列条件下的变形机制，使人们能够将与该过程相关的机械行为或流动规律与其产生的微观结构联系起来。微构造信息可以用来帮助解释自然变形岩石的热机械历史，流动定律可以用来建立更现实的模型，预测不同构造环境下的地壳行为。领域、理论和实验方法之间的迭代对于我们的理解取得进展至关重要。晶体塑性的变形过程是这一体积的主要焦点。地壳的晶体塑性变形在许多方面比地幔的晶体塑性变形要复杂得多，因为大多数地壳岩石是多相集合体，而且在给定的一组条件下，常见的地壳硅酸盐(如石英、长石和云母)的强度非常不同。如图1⇓示意图所示，地壳的屈服强度包络通常使用石英的位错蠕变流动定律绘制，该定律固有地假设石英是控制相并经历稳定的流动。但是，石英位错蠕变的流动规律对于花岗岩的变形来说是一个很好的近似吗？更不用说不同岩性的区域和层的地壳‘李子布丁’了？The CREST…
Crustal deformation is inherently complex because the crust is inhomogeneous and anisotropic on a wide variety of scales. Advances in our understanding have come from a combination of field observations, laboratory experiments and theoretical models. What necessarily links all these investigations is a focus on process. Crystal plasticity (dislocation creep) is one of several grain-scale deformation processes or mechanisms; each process is dominant over a certain range of conditions in the crust, has a particular form of the flow law, and produces a characteristic set of microstructures. Characterizing the deformation mechanisms for different minerals, over a range of conditions, allows one to link the mechanical behavior or flow law associated with that process to the microstructures it produces. The information on microstructures can be used to help interpret the thermomechanical history of naturally deformed rocks, and flow laws can be used to create more realistic models predicting crustal behavior in different tectonic settings. Iterations among field, theoretical, and experimental approaches are critical for making progress in our understanding. The deformation process of crystal plasticity is the main focus of this volume. Crystal plastic deformation of the crust is in many ways more complex than that of the mantle, because most crustal rocks are polyphase aggregates, and the strengths of common crustal silicates (such as quartz, feldspar, and mica) are very different at a given set of conditions. Yield strength envelopes for the crust, as shown schematically in Figure 1⇓, are commonly plotted using the dislocation creep flow law for quartz, which inherently assumes that quartz is the controlling phase and undergoes steady state flow. But is the flow law for dislocation creep of quartz a good approximation for the deformation of a granite, let alone a crustal ‘plum pudding’ of regions and layers of different lithologies? The crust …