A FIRST ATTEMPT AT A PROVENANCE STUDY OF THE JADAR BLOCK, SERBIA

Geochronology of zircon grains retrieved from magmatic rocks intruding the Jadar block terrain in the central Balkans is used here to add new constraints on the terrane accretion processes and the provenance of crustal sources of this potentially exotic crustal block. In this unorthodox approach, we analyzed zircons extracted from the products of Cenozoic (Cer and Boranja granitoid massifs) and Triassic magmatism (Bobija andesitic tuff - Pietra Verde). In about ten samples of granites and epiclastites, we analyzed more than 300 grains and, of these, about 30-40% are derived from the basement and were used further for the geological interpretation. The majority of the samples show a similar Precambrian and Paleozoic age spectrum, including a ubiquitous Neoproterozoic and well-defined Silurian-Ordovician populations. Only a few older zircons are present, composing minor populations at c. 1.2 Ga and 3.2 Ga. The younger zircons represent the Triassic population that is ubiquitous and the strongest in all samples, probably related to the local igneous activity, that is, Permian-Triassic volcanism generated due to the opening of the Neotethys. Only in the Cer multi-phase pluton, the zircon age spectrum shows a strong Carboniferous peak, making an important link to the Herzynian margin of Eurasia. This provides support for the interpretation either that this part of the Jadar block terrain represents a southern continuation of Bükkium” and Sana-Una terrains comprising displaced fragments of the southern European Variscan foreland, or more likely, that the Cer granitic magma assimilated the Cretaceous sediments from the Sava Zone, where these zircons are derived from.