Dislocation structure around fluid inclusions in olivine and orthopyroxene

位错提供了矿物塑性变形的直接证据。我们观察到橄榄石和斜方辉石中流体包裹体周围的位错结构。橄榄石的边缘位错呈环状，其大小与相邻流体包裹体的大小相似，表明位错是流体包裹体超压的结果。环状位错的产生受橄榄石滑移系屈服强度的控制。对于斜方辉石，在c轴上发现了少量的螺位错。两种矿物位错密度的差异表明斜方辉石具有较高的屈服强度。由位错结构估计的橄榄石中流体包裹体的膨胀可以很好地解释矿物之间二氧化碳流体密度的差异，这一事实证实了这一点。包体中流体包裹体周围位错结构的观察有助于评价矿物间滑动体系的相对强度。

Dislocations provide a direct proof of plastic deformation of minerals. We observed dislocation structure around fluid inclusions in olivine and orthopyroxene. For olivine, development of edge dislocations with loop shape whose size is analogous to that of an adjacent fluid inclusion indicate that the dislocations result from excess pressure of the fluid inclusion. The generation of loop dislocations would be controlled by yield strength of slip systems of olivine. For orthopyroxene, a few screw dislocations are identified in c-axis. The difference in dislocation density between both minerals suggests the higher yield strength of orthopyroxene. This is verified by the fact that expansion of a fluid inclusion in olivine estimated by dislocation structure can well explain difference in CO2 fluid density between the minerals. The observation of dislocation structure around fluid inclusions in xenoliths is useful to assess relative strength of slip systems among minerals.