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RESEARCH PRODUCT

Textures and c-axis orientations of deformed quartz crystals from porphyric dikes of the Alpine »Root Zone« (Western Alps)

subject

description

Deformation textures and c-axis preferred orientations of quartz phenocrysts from porphyric dikes of the Alpine »Root Zone« have been formed under conditions of greenschist to low amphibolite facies. It is shown that the deformation textures as shear planes and kink bands, boudins, grain boundary sutures, subgrains, coarse and fine recrystallized grains, deformation lamellae and fractures are developed in a chronological sequence during first increasing and later decreasing temperatures. The c-axis orientations are chiefly influenced by kinking during the early stage of metamorphism and later by recrystallization but not by the initial orientations of the c-axes. The shape of crossed-girdles is related to the type of strain. At the beginning of polygonization during increasing temperatures basal-a glide as a dominant glide mechanism is replaced by prism-c glide and vice versa during decreasing temperatures. The average angular velocity of c-axes is 0.4‡ per 1 % flattening.