Petrology and geochemistry of Egerian-Eggenburgian and Badenian tholeiite-calc-alkaline volcanics from the South Pannonian Basin (Croatia)
Pamić, Jakob; Balen, Dražen
published: Sep 26, 2001
ArtNo. ESP154017603001, Price: 29.00 €
In the South Pannonian Basin, bounded to the south by the North Dinarides, two Tertiary post-orogenic tholeiite-calc-alkaline volcanic associations are found: 1) the Egerian-Eggenburgian one, composed largely of andesites with subordinate basaltic andesites and dacites, and 2) the Badenian one, comprising basalts, basaltic andesites, andesites, dacites and alkali feldspar rhyolites. Ages of the volcanism are constrained by concordant geological and K-Ar data. The petrology and geochemistry of volcanics of both associations are constrained by microprobe analyses, major and trace element analyses and radiogenic isotope data. Despite their different ages, the volcanics of both associations are characterized by similar variations in concentrations of major and trace elements and similar variation intervals. Decreasing contents of MgO (10.5-0.30%), Cr (487-18 ppm), Ni (476-3 ppm) and some other elements relative to SiO2 indicate that these volcanics originated by fractional crystallization from tholeiitic basalt melts, probably generated by partial melting of enriched upper mantle wedge. During fractional crystallization the primary magma was affected by crustal contamination as indicated by increased 87Sr/86Sr and decreased 143Nd/144Nd ratios. In all these geochemical aspects, Egerian-Eggenburgian and Badenian volcanics are similar to the slightly older tonalite suite in the adjacent easternmost parts of Periadriatic Line (Mts. Pohorje and Karavanke). All three geochronologically successive magmatic events can be explained by a slab breakoff model related to underplating of Apulia (Africa) below Tisia (Eurasia).