How geometry and anisotropy affect residual strain in host-inclusion systems: Coupling experimental and numerical approaches
How geometry and anisotropy affect residual strain in host-inclusion systems: Coupling experimental and numerical approaches
复制标题
几何形状和各向异性如何影响主体夹杂物系统中的残余应变：实验与数值方法的耦合
作者：
N. Campomenosi;M. Mazzucchelli;B. Mihailova;M. Scambelluri;R. Angel;F. Nestola;A. Reali;M. Alvaro
摘要拉曼光谱提供了主体-包裹体系统残余应变状态的信息，结合弹性地质压力理论，可用于反演包裹体包裹的P-T条件。在现场拉曼测量锆石和柯石英夹杂物石榴石超高压多拉Maira地块表明，圆形夹杂物表现出恒定的拉曼位移在其整个体积。相反，我们证明了拉曼位移可以从中心到边缘和角落的小面夹杂物。石榴石基质的分步抛光表明，圆形和棱柱形夹杂物中的应变随着夹杂物接近基质的自由表面而逐渐释放。更重要的是，我们的实验结果加上选定的数值模拟表明，应变释放的幅度和速率也取决于主机和夹杂物之间的弹性性能的对比度和夹杂物的结晶取向相对于外表面。这些结果使我们能够提供新的方法学指导，以确定在主机包合系统中的残余应变。
Abstract Raman spectroscopy provides information on the residual strain state of host-inclusion systems that, coupled with the elastic geobarometry theory, can be used to retrieve the P-T conditions of inclusion entrapment. In situ Raman measurements of zircon and coesite inclusions in garnet from the ultrahigh-pressure Dora Maira Massif show that rounded inclusions exhibit constant Raman shifts throughout their entire volume. In contrast, we demonstrate that Raman shifts can vary from the center to the edges and corners of faceted inclusions. Step-by-step polishing of the garnet host shows that the strain in both rounded and prismatic inclusions is gradually released as the inclusion approaches the free surface of the host. More importantly, our experimental results coupled with selected numerical simulations demonstrate that the magnitude and the rate of the strain release also depend on the contrast in elastic properties between the host and the inclusion and on the inclusion crystallographic orientation with respect to the external surface. These results allowed us to give new methodological guidelines for determining the residual strain in host inclusion systems.