Petrological And Geochemical Features Of The Neogene Volcanites Of The Osogovo Mountains, Eastern Macedonia

摘要

The subject of the presented study was the petrological and geochemical characterization of the Neogene volcanic rocks from the Osogovo Mountains. In this paper we present new results of petrological and geochemical analyses of igneous rocks, mostly from Sasa, Toranica and Ruen. The mineralogical and geochemical characteristics of the studied rocks confirmed the results of some previous investigations that indicated that the exposed lithologies are mostly dacites. quartzlatitcs, trachyandesites, lamprophyres and rhyolitcs. An absolute age determination using a standard K-Ar method gives ages between 31.16 + - 1.40 and 14.0 + - 3.0 m.y., and also confirmed their proposed Oligocene-Miocene age. The parent material of these rocks is supposed to originate from the contact zone between the lower crust and upper mantle. A possible assimilation of crustal material during magma formation was also suggested. This supposition was further confirmed by the results of the strontium isotope ((87)~Sr/~(87)Sr) ratios, which are in the range from 0.70954 to 0.71126. as well as by other geochemical characteristics.