Granitoids of the Odra Fault Zone: late- to post-orogenic Variscan intrusions in the Saxothuringian Zone, SW Poland

Authors

  • Teresa Oberc-Dziedzic Instytut Nauk Geologicznych, Uniwersytet Wrocławski, M. Borna 9, 50-204 Wrocław, Poland
  • Andrzej Żelaźniewicz Instytut Nauk Geologicznych PAN, Zakład Geologii Sudetów, Podwale 75, 50-449 Wrocław, Poland
  • Stefan Cwojdziński Państwowy Instytut Geologiczny, Oddział Dolnośląski, Jaworowa 19, 53-122 Wrocław, Poland

Keywords:

Fore-Sudetic Block, granitoid, Mid-German Crystalline Rise, Odra Fault Zone, Saxothuringian Zone, Variscides, Sudetes.

Abstract

There are 5 occurrences of granodioritic to monzogranitic rocks found subsurface along the Odra Fault Zone a Permo-Mesozoic horst defining the northeastern edge of the Bohemian Massif. These are generally unfoliated,  I-type granitoids with low A/CNK and initial Sr/Sr ratios making them geochemically and petrographically akin to late- to post-kinematic Variscan granitoids of the West Sudetes, being closest to those of the eastern part of the Fore-Sudetic Block (Strzelin, Niemcza). They represent late/post-orogenic, collisional intrusives of  Early-Late Carboniferous age which are widespread throughout the Saxothuringian and Moldanubian zones in the Bohemian Massif. The country rocks to the granitoids are mica schists and paragneisses attaining staurolite-grade. The granitoids lack evidence of ductile or brittle strike-slip movement of  Late Carboniferous-Permian age along the Odra Fault Zone, which thus has to be taken as a dip-slip fault zone, rather than a late Variscan dextral strike-slip feature. Brittle to semi-brittle deformation of the Odra granitoids relates to the formation of the horst during Permo-Mesozoic times. A Silurian-Early Devonian magmatic arc of the Mid-German Crystalline Rise, identified further to the west in Germany, probably does not have an easterly prolongation into Poland because there is no evidence for arc-related magmatism

Downloads

Published

2008-05-19

Issue

Section

Articles