ARC Centre of Excellence for Core to Crust Fluid Systems/GEMOC, Department of Earth and Planetary Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirawee DC, New South Wales 2232, Australia.
Nat Commun. 2017 Jan 27;8:14032. doi: 10.1038/ncomms14032.
Deformation microstructures are widely used for reconstructing tectono-metamorphic events recorded in rocks. In crustal settings deformation is often accompanied and/or succeeded by fluid infiltration and dissolution-precipitation reactions. However, the microstructural consequences of dissolution-precipitation in minerals have not been investigated experimentally. Here we conducted experiments where KBr crystals were reacted with a saturated KCl-HO fluid. The results show that reaction products, formed in the absence of deformation, inherit the general crystallographic orientation from their parents, but also display a development of new microstructures that are typical in deformed minerals, such as apparent bending of crystal lattices and new subgrain domains, separated by low-angle and, in some cases, high-angle boundaries. Our work suggests that fluid-mediated dissolution-precipitation reactions can lead to a development of potentially misleading microstructures. We propose a set of criteria that may help in distinguishing such microstructures from the ones that are created by crystal-plastic deformation.
变形微结构被广泛用于重建岩石中记录的构造变质事件。在地壳环境中，变形通常伴随着流体的渗透和溶解-沉淀反应，或者是在其之后发生。然而，矿物中溶解-沉淀的微观结构后果尚未经过实验研究。在这里，我们进行了实验，其中 KBr 晶体与饱和的 KCl-HO 流体反应。结果表明，在没有变形的情况下形成的反应产物继承了其母体的一般结晶取向，但也显示出一些新的微观结构的发展，这些结构在变形矿物中很典型，例如晶格的明显弯曲和新的亚晶粒畴，这些新的微观结构由低角度和（在某些情况下）高角度边界分隔。我们的工作表明，流体介导的溶解-沉淀反应可能导致潜在误导性微观结构的发展。我们提出了一组可能有助于区分这种微观结构和由晶体塑性变形产生的微观结构的标准。
