The Kedrovyi-Butachikha dynamic metamorphic zone (Rudny Altai): a tectonic model

摘要

Structures of dynamic metamorphism have been traditionally studied proceeding from their similarity with faults, according to stratigraphic criteria and with reconstructions of predeformation settings. Using the example of the Kedrovyi-Butachikha shear zone in Rudny Altai, we suggest to distinguish zones with abundant dynamic metamorphic rocks (tectonites) as a special class of structures. Their diagnostic features are (i) dense fault populations, with mostly strike slip geometry of motion and intense mechanic failure and rework of the substrate; (ii) generally coordinated orientations (anisotropy) of structural elements at all hierarchic levels; and (iii) ordered patterns of laminar and turbulent flow. Complexes of tectonites in the Kedrovyi-Butachikha shear zone have been classified into dynamic clastics, tectonic schists, tectonic mixtites, and mechanic metasomatites according to their lithological and structural features. The new classification is used to image the architecture of the dynamic metamorphic zone in a map model which shows the pattern of tectonite complexes with their substrate unevenly reworked by shear-induced metamorphism.