Der Schwerzer Rhyolith-Komplex: Beitrag zur Verbreitung und Struktur einer der ältesten Einheiten des Halleschen Vulkanitkomplexes

Abstract

Krauss, G.: The Schwerz Rhyolithe Complex – Distribution and structure of one of the oldest units of the Halle Volcanic Complex. - Hercynia N.F. 36: 129–150.At the Carboniferous/Permian boundary intense magmatic activity occurs in many parts of the NE German Basin. The Schwerz Rhyolithe Complex, well exposed in the quarry Schwerz near Halle/Saale, represents a separated unit of varieties of rhyolithes within the eastern part of the Halle Volcanic Complex (HVC). With 206Pb/238U ages of 307 ± 3 Ma the Schwerz Rhyolithe Complex is one of the oldest units of the HVC. We present recent investigations about the texture of the rhyolithes as well as structural attributes of contact zones between the different rhyolithe units. Modal analyses of the main minerals quartz, Kfeldspar and plagioclase show that the medium crystalline black rhyolithes texture is more similar to the Petersberg- and Wettin-type of rhyolithes in the HVC whereas the coarse crystalline units are more similar to the Löbejün- and Landsberg-type of rhyolithes. The absence of flow textures and the medium crystalline character of the rocks may assume that the rhyolithes within the Schwerz Complex have developed intrusively near the surface.