Evolution of the Štiavnica Stratovolcano revisited: SHRIMP U–Th–Pb zircon dating of subvolcanic intrusions, caldera fill and B. Hodruša precious/base metal deposit (including Re/Os and K/Ar data)

A general timing of the tiavnica Stratovolcano edifice evolution based on structural relationships, biostratigraphic data and previous dating by K/Ar and Rb/Sr methods could not resolve more exactly the critical interval of the subvolcanic intrusive complexes emplacement, a caldera subsidence and evolution of related mineralizations.To fill the gap we have carried out 20 precise SHRIMP U-Th-Pb zircon datings of relevant intrusive and volcanic rocks as well as K/Ar dating of illite and adularia and Re/Os dating of gold and sulfides from a related epithermal mineralization.Their high precision allowed to recognize a succession of subvolcanic intrusions concluded by the caldera collapse and to establish age of the B. Hodrua precious/base metal epithermal mineralization.Based on new interpreted age intervals for individual stages and sub-stages in a complex evolution of the tiavnica Stratovolcano edifice we update the scheme of its evolution as follows: (1) construction of an extensive and complex andesite stratovolcanic edifice during the interval 15.0-13.6Ma, including emplacement of a diorite intrusion around 14.8 Ma and emplacement of a diorite porphyry stock at Beluj 14.5 Ma; (2) emplacement of subvolcanic intrusive rocks including: emplacement of rare quartz-diorite porphyry sills pre-dating the B. Hodrua epithermal mineralization around 13.6 Ma; emplacement of the granodiorite bell-jar pluton around 13.44 Ma; granodiorite pluton resurgent uplift, sector collapse and related evolution of the B. Hodrua epithermal mineralization in the interval of ca.13.44-13.31Ma; emplacement of quartz-diorite sills in the shear zone that post-date the epithermal mineralization around 13.31 Ma; emplacement of other quartz-diorite porphyry sills and ring dikes during the interval of ca.13.3-13.0Ma; emplacement of granodiorite porphyry stocks and dike clusters around 12.9 Ma; (3) subsidence of the caldera and its filling by evolved andesites around 12.9 Ma; (4) renewed activity of less evolved and mixed type andesites during the interval of ca.12.8-12.3Ma; (5) uplift of the resurgent horst in the central part of the caldera accompanied by rhyolite volcanic/intrusive activity between 12.3 and 11.4 Ma.