P-T data of Ky-St-Grt gneisses hosting HP amphibolites and eclogites from the Austroalpine Polinik complex, Kreuzeck Mountains, Eastern Alps, Austria

Abstract

This study focuses on metapelites of the Polinik complex in the Kreuzeck Mts. southeast of the Tauern Window, Eastern Alps, where kyanite -staurolite -garnet gneisses host eclogites and high pressure (HP) amphibolites of the Austroalpine basement. The stable mineral assemblage is garnet -staurolite -biotite -kyanite -quartz. Estimated metamorphic conditions from conventional geothermobarometry are 654±30 • C and 0.9±0.08 GPa, and Average P-T values calculated by THERMOCALC, are 665±15 • C at 0.77±0.09 GPa. Formation of the present mineral association in gneisses is related to the exhumation (D2) stage of hosted eclogites/HP amphibolites within a lateral strike-slip zone.

Selected Type-Localities of Potassic Igneous Rocks from the Five Tectonic Settings

“…The Strieden Unit in the south is composed of sillimanite-bearing metapelites, but without any evidence for eclogite-facies metamorphism (Konzett et al 2012). Although no quantitative age data are available, the protoliths are estimated to be older than Permo-Carboniferous (Lahusen 1972;Michàlek et al 2011). In the prevailing plate tectonic models, the Kreuzeck Mountains form part of the Adriatic plate which overrode South Penninic units during the Eocene continent-continent collision.…”

“…European-African plate collision and Alpine nappe emplacement in the late CretaceousEocene were followed by a significant phase of mafic to felsic Oligocene dyke magmatism, mostly concentrated along a major (700 km), east-west-trending Tertiary suture, the Periadriatic Lineament (Exner 1976;Michàlek et al 2011;Konzett et al 2012;Bartel et al 2014). This lineament, also known as the Insubric Line, forms a dextrally transpressive intracontinental branch of the Europe-Africa plate boundary (Laubscher 1988).…”