The diapiric emplacement and related magmatic fabrics of the porphyritic Ludwigshohe granite, Central Odenwald (Germany)

The Ludwigshohe pluton is a 1.5 by 2.5 km, oval-shaped, NE-SW oriented, dis tinct body of medium-grained porphyritic granite with large euhedral to len soid K-feldspar phenocrysts and discoidal microdioritic enclaves. The granite shows a well developed NE-SW striking, steeply inclined foliati on defined by mafic minerals, K-feldspar phenocrysts, and enclaves. All phe nocrysts have an orthorhombic symmetry with respect to the foliation. Monoc linic shear sense criteria are absent. Shape orientation analysis of enclav es, K-feldspar phenocrysts, magmatic hornblende and plagioclase and strain analyses (R-f/Phi) result in uniaxial, oblate ellipsoids, plotting in the f ield of apparent flattening on the Flinn diagram. In thin section no penetrative ductile deformation of feldspars, hornblende and biotite can be observed. Twinning in feldspars occurs parallel to thei r flat faces, which are oriented parallel to the magmatic foliation. Quartz , growing in interstitial positions, shows early penetrative ductile deform ation under high temperature (HT) late magmatic/ early solid-state conditio ns and later deformation under low temperature (LT) conditions accompanied by sinistral shear. The latter is responsible for an oblique orientation of the quartz c-axes fabric. AMS studies as well as cathodoluminescence investigations and quartz c-axes textures indicate flattening processes under a NW-SE directed compressive strain regime during the magmatic stage and/or emplacement of the granites.