Auriferous arsenopyrite–pyrite and stibnite mineralization from the Siflitz–Guginock area (Austria): indications for hydrothermal activity during Tertiary oblique terrane accretion in the Eastern Alps
G. Amann, W. H. Paar, F. Neubauer, G. Daxner, 2002. "Auriferous arsenopyrite–pyrite and stibnite mineralization from the Siflitz–Guginock area (Austria): indications for hydrothermal activity during Tertiary oblique terrane accretion in the Eastern Alps", The Timing and Location of Major Ore Deposits in an Evolving Orogen, D. J. Blundell, F. Neubauer, A. von Quadt
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Polymetamorphic schists and marbles of the Austroalpine Kreuzeck–Goldeck Complex are the host to auriferous arsenopyrite–pyrite as well as stibnite mineralization. In the Siflitz–Guginock area both types of mineralization are closely related spatially, but restricted to different lithologies. The auriferous arsenopyrite–pyrite mineralization is either disseminated or bound to quartz veins and strongly silicified fault-zones hosted in phyllites to (garnet-) micaschists. Similar disseminations within marbles are of minor importance. A stockwork-like mineralization of stibnite-filled fractures with weak metasomatic replacement is limited to marbles.
Both types of mineralization in the Kreuzeck–Goldeck Complex are intimately related to roughly east–west-trending semi-ductile to brittle strike-slip faults which formed during orogen-parallel wrenching. Semi-ductile to brittle kinematic indicators point to dextral, as well as sinistral, modes of fault movements, coeval with the formation of pyrite–arsenopyrite-bearing quartz veins, as well as the intrusion of Oligocene lamprophyre dykes. Mineralizing fluids are suggested to be derived from devolatilization of the subducted Penninic upper crust. Fluid ascent and ore precipitation is controlled by a transpressive strike-slip regime related to oblique terrane accretion during the Late Eocene to Oligocene.
Subsequent development of a Late Oligocene–Early Miocene pure shear regime with contraction trending (N)NE–(S)SW led to the development of conjugate NW–SE dextral and NE–SW sinistral brittle strike-slip faults, and overprinting by ESE–WNW oriented extension. These later events are related to the formation of auriferous mineralization from within the metamorphic core complex of the Tauern Window to the north of the Kreuzeck–Goldeck Complex, hence implying a significant change in spatial, temporal and structural control of Tertiary auriferous mineralization in the Eastern Alps.