Geochemistry and geodynamics of a Late Cretaceous bimodal volcanic association from the southern part of the Pannonian Basin in Slavonija (Northern Croatia) (CROSBI ID 83674)
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Pamić, Jakob ; Belak, Mirko ; Bullen, Tom ; Lanphere, Marvin ; McKee, Edwin
engleski
Geochemistry and geodynamics of a Late Cretaceous bimodal volcanic association from the southern part of the Pannonian Basin in Slavonija (Northern Croatia)
In this paper we present a bimodal basalt-rhyolite suite associated with A-type granites of Late Cretaceous age from the South Pannonian Basin in Slavonija (Croatia). Basalts and alkali-feldspar rhyolites associated in some places with ignimbrites, occur in volcanic bodies that are interlayered with pyroclastic and fossiliferous Upper Cretaceus sedimentary rocks. Basalts that are alkalic to subalkalic and their geochemical signatures, particularly trace element and REE patterns are similar to recent back-arc basalts. Alkali-feldspar rhyolites have similar geochemical features as the associated cogenetic A-type granites. Geochemical data indicate an amphibole lherzolite source within a metasomatized upper mantle wedge with the influence of upper mantle diapir with MORB signatures and continental crust contamination. Sr incorporated in the primary basalt melt had an initial 87Sr/86Sr ratio of 0.7039 indicating its upper mantle origin, whereas the 87Sr/86Sr ratio for the alkali-feldspar rhyolites and associated A-type granites is 0.7073 indicating their apparent continental crust origin. However, some other geochemical data favour the idea that they might have mainly originated by fractionation of primary mafic melt coupled with contamination of continental crust. Only one rhyolite sample appears to be the product of melting of continental crust. Geological and geodynamical data indicate that the basalt-rhyolite association was probably related to Alpine subduction processses in the Dinaridic Tethys which can be correlated with recent back-arc basins. The difference in geological and isotope ages between the bimodal basalt-rhyolite volcanism with A-type granite plutonism (72 Ma) and the final synkinematic S-type granite plutonism (48 Ma) can be taken as a lifetime of the presumed BARB system of the Dinaridic Tethys.
Late-Cretaceous bimodal volcanic association; BARB; geochemistry
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