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  • Tectonic, magmatic, and met...
    Gallhofer, Daniela; Quadt, Albrecht von; Peytcheva, Irena; Schmid, Stefan M.; Heinrich, Christoph A.

    Tectonics (Washington, D.C.), September 2015, Letnik: 34, Številka: 9
    Journal Article

    The Apuseni‐Banat‐Timok‐Srednogorie Late Cretaceous magmatic arc in the Carpathian‐Balkan orogen formed on the European margin during closure of the Neotethys Ocean. It was subsequently deformed into a complex orocline by continental collisions. The Cu‐Au mineralized arc consists of geologically distinct segments: the Apuseni, Banat, Timok, Panagyurishte, and Eastern Srednogorie segments. New U‐Pb zircon ages and geochemical whole rock data for the Banat and Apuseni segments are combined with previously published data to reconstruct the original arc geometry and better constrain its tectonic evolution. Trace element and isotopic signatures of the arc magmas indicate a subduction‐enriched source in all segments and variable contamination by continental crust. The magmatic arc was active for 25 Myr (~92–67 Ma). Across‐arc age trends of progressively younger ages toward the inferred paleo‐trench indicate gradual steepening of the subducting slab away from the upper plate European margin. This leads to asthenospheric corner flow in the overriding plate, which is recorded by decreasing 87Sr/86Sr (0.70577 to 0.70373) and increasing 143Nd/144Nd (0.51234 to 0.51264) ratios over time in some segments. The close spatial relationship between arc magmatism, large‐scale shear zones, and related strike‐slip sedimentary basins in the Timok and Pangyurishte segments indicates mild transtension in these central segments of the restored arc. In contrast, the Eastern Srednogorie segment underwent strong orthogonal intraarc extension. Segmental distribution of tectonic stress may account for the concentration of rich porphyry Cu deposits in the transtensional segments, where lower crustal magma storage and fractionation favored the evolution of volatile‐rich magmas. Key Points Major magmatic arc concealed by postsubduction continental collision Europe's active margin reconstructed using magma chemistry and geochronology Distribution of magmatic‐hydrothermal ore deposits controlled by stress state