Original paper

Die magmatischen Gesteine des Bergsträßer Odenwaldes und ihre Platznahme-Geschichte

Stein, Eckardt

Kurzfassung

Die Mikrogefüge der gesteinsbildenden Minerale in den magmatischen Gesteinen des Bergsträßer Odenwaldes sind typisch für eine magmatische Entwicklung. Lediglich die Quarz-Gefüge zeigen deutliche kristallplastische Verformungen, die aus Festkörper-Verformungen abgeleitet werden. Daraus resultierend werden für die Intrusiva des Bergsträßer Odenwaldes verschiedene Platznahme-Mechanismen abgeleitet: es gibt deutliche Hinweise für Ballooning, für sog. nested diapirs und für Stoping.

Abstract

Microstructural features of the magmatic rocks of the Bergsträßer Odenwald are typical for a magmatic origin of their planar and linear fabrics. Quartz forms the only exception with its crystal-plastic deformation ranging from undulous extinction to dynamic recrystallisation. They are mostly interpreted as solid-state fabrics forming after the complete solidification of the magma under brittle or brittle/ductile conditions. All investigations of the planar fabric in the magmatic rocks of the Flasergranitoid zone and of the Weschnitz-Pluton support an interpretation as result of flattening processes, which are due to a compressional stress field and not due to a transtension as Krohe and Willner et al. proposed. Such a stress displayed in the magmatic rocks, their shapes, and their concentric fabric can be explained well by a successive diapirism according to the ballooning and/or nested diapir model. Additionally, stoping contributes as an important emplacement mechanism to the space-making which is especially obvious in the S parts of the Flasergranitoid zone with its exposed pluton roofs.

Keywords

Microstructuremagmatic rockBergsträßer OdenwaldgermanyBallooningnested diapirFlasergranitoid zone