Inhaltszusammenfassung

The geometry of microstructures is an important source of information on the development of mylonite zones and on the kinematics and dynamics of flow in them. Shear band cleavage is an important as a commonly used shear-sense indicator in mylonites, although its development is incompletely understood. Two types of shear band cleavage are distinguished in the literature: S-C-type and S-C'-type cleavage (Berthé et al. 1979a, b) (Figure 1). In our experiment we focused on the development of S-C'...The geometry of microstructures is an important source of information on the development of mylonite zones and on the kinematics and dynamics of flow in them. Shear band cleavage is an important as a commonly used shear-sense indicator in mylonites, although its development is incompletely understood. Two types of shear band cleavage are distinguished in the literature: S-C-type and S-C'-type cleavage (Berthé et al. 1979a, b) (Figure 1). In our experiment we focused on the development of S-C' type cleavage (Figure 2), which is common in micaceous mylonites: S (cleavage) planes represent a penetratively developed foliation and spaced C'-type shear bands are oblique to shear zone boundaries and to the S-planes (White 1979b, Platt and Vissers 1980) (Figure 1). The angle between shear bands and the shear zone margin is 15-35o (Dennis and Secor 1987, Passchier 1991b, Blenkinsop and Treloar 1995). Normally, only one set of shear bands is developed, with a sense of slip synthetic to the shear-sense of bulk flow. The shear bands may be composed of the same mineralogy as the rest of the rock (e.g. Gapais and White 1982) or they may show compositional changes typical of retrograde metamorphic reactions (e.g. McCaig 1987, Norrell et al. 1989) or of the concentration of less soluble material by mass transfer.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
3.31 - Mathematik

DDC Sachgruppe:
Geowissenschaften