engleski

Origin and geodynamic evolution of Late Paleogene magmatic associations along the Periadriatic-Sava-Vardar magmatic belt

Along the Periadriatic Lineament in the Alps and the Sava-Vardar Zone of the Dinarides and Hellenides, Paleogene magmatic associations form a continous belt, about 1700 km long. The following magmatic associations occur: 1) Eocene granitoids ; 2) Oligocene granitoids including tonalites ; 3) Oligocene shoshonite and calc-alkaline volcanics with lamprophyres, and 4) Egerian-Eggenburgian (Chattian) calc-alkaline volcanics and granitoids. All of these magmatic associations are constrained by radiometric ages, which indicate that the magmatic activity was mainly restricted to the time span between 55 and 29 Ma. These igneous rocks form, both at surface and in the subsurface, the distinct linear Periadriatic-Sava-Vardar magmatic belt with three strikes that are controlled by indentation of Apulia and Moesia and accompanying strike-slip faulting. The geology, seismicity, seismic tomography and magnetic anomalies within this belt suggest that it has been generated in the African-Eurasian suture zone. Based on published analytical data, the petrology, major and trace element contents and Sr, Nd and O isotopic composition of each magmatic association is briefly defined. These data show that Eocene and Oligocene magmatic associations of the Late Paleogene Periadriatic-Sava-Vardar magmatic belt originated along a consuming plate margin. Based on isotopic systems, two main rock groups can be distinguished with: 1) 87Sr/86Sr=0.7036-0.7080 and d18O=5.9-7.2‰ indicating basaltic partial melts derived from a continental mantle-lithosphere, and 2) 87Sr/86Sr=0.7090-72131 and d18O=7.3-11.5‰ indicating crustal assimilation and melting. The mantle sources for the primary basalt melts are metasomatized garnet peridotites and/or spinel lherzolites and phlogopite lherzolites of the upper mantle wedge origin. The geodynamic evolution of the plutonic and volcanic associations of the Periadriatic-Sava-Vardar magmatic belt was related to the Africa-Eurasia suture zone that was dominated by break-off of the subducted lithospheric slab of Mesozoic oceanic crust, at depths of 90-100 km. This is indicated by their contemporaneity along the 1700 km long belt.

geodynamics; Late Paleogene; magmatic associations; Periadriatic-Sava-Vardar magmatic belt

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