0000000000505533
AUTHOR
S. W. J. (Bas) Den Brok
Analysis of a complex high-strain zone at Cap de Creus, Spain
Abstract The structural analysis of a high-strain zone developed in medium- to high-grade metamorphic micaschists from the Cap de Creus area, Spain provides an example of the complex relationships between geometry, strain and kinematics to be found in deep crustal shear zones. This high-strain zone is composed of E-W trending structural domains characterized by different strain intensities and associated with syntectonic emplacement of pegmatite dykes. The main phase of deformation discussed here, D2, affects steeply dipping bedding, boudinaged quartz veins and S1 developed parallel to bedding. D2 deformation of these features and of syn-D2 pegmatite dykes gives rise to fold/boudin structur…
Effect of microcracking on pressure-solution strain rate: The Gratz grain-boundary model
Different, but reasonable and well-accepted assumptions made about grain-boundary structure during pressure-solution (PS) creep may easily have an effect of more than 10 orders of magnitude on the calculated PS deformation rate. Understanding of grain-boundary structure during PS creep is therefore extremely important. Experimental evidence is presented in support of a grain-boundary model previously proposed by A. J. Gratz on the basis of observations on naturally deformed rocks. In this model, boundaries are assumed to have a static island-channel network structure. Channels are located where microcracks intersect the boundary. The rate of material transport is governed by thin-film diffu…