Pre‐Alpine eclogites in the Pennine Basement Complex of the Eastern Alps

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Abstract
An occurrence of quartz‐eclogite is described from the Inner Schieferhülle unit of the Pennine Basement Complex in the SE Tauern Window, Austria.Field relations strongly suggest a pre‐Alpine age for the primary eclogitic mineral assemblage (garnet + omphacite + quartz + rutile). This implies that there was no connection between the formation of these eclogites and the late Cretaceous and Tertiary tectonic evolution of the Eastern Alps. The quartz‐eclogite mineral assemblage crystallized under conditions of 620 ± 100°C and at pressures in excess of 12 kbar, and suffered amphibolitic overprinting of Alpine and possibly Hercynian age.A four‐stage polymetamorphic history is proposed for the Inner Schieferhülle: