The Late Paleozoic felsic lava-dominated large igneous province in northeast Germany: volcanic facies analysis based on drill cores

In the deep subsurface of the northeast German basin products of extensive volcanism are present that formed during the waning phase of the Variscan orogeny (Permian–Carboniferous boundary). Large volumes (≥48,000 km³) of dominantly felsic magma were emplaced in the northern foreland of the Variscan mountains in a terrestrial semi-arid environment. Most of these units were inferred by previous authors to represent the products of explosive volcanic eruptions such as ignimbrites. However, a detailed analysis of the volcanic texture and lithofacies association shows that most units are best interpreted as coherent lavas emplaced either as extrusive units or as shallow intrusions, with important implications for the reconstruction of the paleo-environment. This study shows that detailed textural examination of drill cores provide important observations, which can be applied as criteria for the interpretation of the mode of volcanic eruptions. Furthermore, phenocryst logging and geochemical fingerprinting based on immobile element ratios can be employed for the classification and discrimination of individual emplacement units.