The Structural Evolution of an Orthogneiss-fold Within the Reitzenhainer Rotgneisstruktur (Erzgebirge Mts., GDR)

The crystallographic preferred orientations of quartz in gneiss taken from different spots of arecumbent fold structure in the Erzgebirge Mts. (southern GDR) are studied by means of neutrontime-of-flight diffraction. A single component texture has been found for all specimens, with quartz c -axes parallel to the tectonic a -direction. The variations in texture sharpness are related to differentdeformation conditions of the samples. A fabric rotation of 30° has been found from the limb to thecrest of the fold on the basis of ( 10 1 ¯ 0 ) and ( 11 2 ¯ 0 ) pole figures. The basal pole figures of quartz derivedfrom an ODF analysis compared well with optical U-stage measurements. The determined fabrics arediscussed taking into account model calculations of experimentally deformed quartzites and geologicalinformations.