Sudbuction-related terrestrial igneous/volcanic environments provide one of the most favorable conditions for hydrothermal ore genesis as recorded by world-class volcanic-hosted deposits along active and collided continental margins. A number of key factors related to magmatic/volcanic activity contribute to the effectiveness of those environments in concentrating metals present at low contents in large volumes of magma and/or country rocks within smaller volumes of high-concentration ore bodies. Such factors invariably include the presence of persistent and focalized heat-sources fueling the “hydrothermal engine” by hydrous fluid circulation in the shallow crust leading to metal extraction, transport and concentration through time. Here we focus on the role of the time factor in controlling both heat-source persistency and metal availability in the Neogene volcanic areas of the Carpathian-Pannonian Region (CPR). Based on K-Ar geochronology (> 1400 data), patterns of time-space evolution of Neogene volcanism and ore mineralization in CPR have been identified in both the back-arc part of the orogenic system and the fold-and-thrust arc, as follows.
1. In the back-arc intra-Carpathian region petrochemistry of volcanism has evolved in the order: felsic calc-alkaline, intermediate-acidic and then alkaline. The total duration of volcanic activity is about 20 Ma (from 21 to < 1 Ma), however, ore fertile stages are clearly related to the intermediate-acidic volcanism which has more restricted time span starting at around 17-14 Ma and lasting to about 5-7 Ma in different areas. The most striking observation is that the major stage of ore deposition occurred in a relatively narrow time interval between 11 and 14 Ma. Localization of major ore deposits are controlled by regional fault systems interacting with evolved volcanic structures. These ore deposits mostly represent differentially eroded parts of deep-seated intrusion-related low-sulfidation type epithermal systems in their exposures. The exception is the Apuseni Mts. where an additional younger ore stage with Cu (-Au) porphyry ores occurred at 9 Ma in relation to emplacement of shallow andesitic intrusions.
2. In the Carpathian arc portion of CPR two evolution patterns can be distinguished:
2a. a slowly migrating (from west to east) persistent ca. 700 km long intermediate/felsic calc-alkaline magmatic arc from Eastern Moravia to Bârgău Mts., in the 15-7 Ma time range. Ore deposition occurred in the southeastern part of the arc, again in a relatively narrow time interval between 8 and 11 Ma. Localization of these ore deposits are mostly controlled by shallow andesitic intrusions.
2b. a transient, fast-migrating (from north-west to south-east) volcanism along the ca. 160 km long Călimani-Gurghiu-Harghita (CGH) range in the East Carpathians (11- < 0.05 Ma) without important ore mineralization.
In general, duration of magmatic activity in individual areas is particularly significant if taking into account a “magmatic focusing factor” (i.e. duration of magmatism weighted by occurrence area of its products): longer-lasting magmatism in a smaller area both in the groups of 1 and 2a results in higher ore productivity as compared to shorter-lasting and/or larger occurrence area magmatism in the 2b group. On the other hand, regional scale fault systems related to the back-arc tectonism as long-living controlling factors (group 1), as well as occurrences of shallow intrusions as short-living local factors appear to be also important in defining ore mineralization (group 2). Post-mineralization uplift/subsidence related to the Carpathian collision and basin inversions defines erosion levels in different areas and thus ore types (from shallow epithermal to porphyry levels) observed in exposures.