Petrofabric Analysis of a Drag Fold

HARA lkuo

廣島大學地學研究報告

Geological report of the Hiroshima University

A simple type of a drag fold of siliceous phyllite found in the Sangun metamorphic formation near the Nakase mine, Hyogo Pref., Western Japan, has been analysed with reference to the mica fabric, the quartz c-axis fabric and the quartz lamellae fabric, and the stress and movement picture in the deformation related to the latter two have been discussed. The stress and movement picture through the fold (drawn with reference to those fabric elements) have been fairly well correlated with those in the experimental bending of sheets. The petro-fabric technique of fold analysis after J. LADURNER (1954a) seems not always to be available for synthesis of the mechanics of folding even when a single marked maximum occurs in the c-axis diagram prepared in each sector of the fold. The rule of the establishment of the stess system (the axis of maximum compressive stress and that of maximum tensile stress) with respect to the lamellae inclined at moderate to low angles to the c-axis of quartz has been also discussed.

eng

廣島大學理學部地學教室

[ISSN] 0073-2303

[NCID] AN00213676