Basalts and diabases from the uppermost part of Magdalensberg formation in Slovenia outcrop north of the Periadriatic fault system. They represent the remnant of the Austroalpine Palaeozoic basement, that was brought to the surface durring the uplift of Northern Karawanke mountains. Mafic rocks occur as pillow lavas and subsurface intrusions, accompanied by basaltic breccias, produced by quench fragmentation on the contact with seawater. Rocks are aphanitic to coarse-grained in texture with pyroxene and/or plagioclase phenocrysts. We classify them as ordinary gabroiddic extrusive rocks. Mafic rocks are spilitised with evident chloritisation, carbonatisation, silification and minor epidotisation. Mineral assemblage filling hydrothermal veins represents calc-propylitic alteration typical for submarine hydrothermal systems at temperatures 250–400°C. Geochemical and mineralogical analysis reveal the evolution of slightly alkaline source melt with fractional crystallisation. High concentrations of Nb, Ta and Ti indicate within plate affinity. Trace element ratios suggest low degrees of partial melting in the depths of garnet peridotite stability and intrusion of magma in the area of attenuated lithospheric crust. Based on the stratigraphy the age of the volcanics is estimated to be between Lower Devoian and Lower Carboniferous. Durring that time the Austroalpine unit is thouht to be a part of fragmented ribbon-like Galatian terranes which drifted toward Laurasia due to the opening of Palaeothetys ocean. Magmatic intrusions in the center of the submerged rift zone probably reflect the last stages of crustal extension before the incorporation of the terrane in Variscan orogeny.
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