Dynamic Interpretation of the Simple Type of Calcite and Quartz Fabrics in the Naturally Deformed Calcite-Quartz Vein

HARA Ikuo

Journal of science of the Hiroshima University. Series C, Geology and mineralogy

The calcite and quartz fabrics in a deformed calcite-quartz vein found in the Sangun metamorphic formation at Hirose, Yamaguchi Pref., Western Japan, have been analysed, and the syn-chronization of both fabrics has been examined. The stress systems in the deformations, which produced the observed calcite fabrics, have been established in the light of what has been determined in the fabrics of experimentally deformed single crystals of calcite and marbles, and the quartz fabrics have been inter-preted with reference to those stress systems. Small circle girdle pattern with angular radius of ca. 30° in the quartz lattice fabric in the vein has been clearly correlated with compressive stress directed parallel to the center of the small circle girdle, accompanied with almost equal amount of extension in all of the directions within the plane normal to the compression axis. It is pointed out that the c-axes of quartz may be stable at ca. 30° to the compression axis or at ca. 60° to the tension axis under such stress condition. The lamellae in quartz grains have been interpreted as the structure of late stage unrelated to the deformation which induced the lattice and dimensional fabrics of the quartz grains. The regular positional relationships between the c-axis of the host crystal and the corresponding lamellar pole and between the c-axis of the lamellar crystal and that of the corresponding host crystal have been recognized in the composite diagrams of those axial data for the quartz grains containing lamellae. It is pointed out that those relationships will be used to synthesize the stress system in the deformation related to the formation of lamellae.

eng

HIROSHIMA UNIVERSITY

[ISSN] 0075-4374

[NCID] AA00706718