中央ヨーロッパ，カルパティア・パンノニア地域における中新世の大規模な火成活動について—北東部のマグマ発生および分化メカニズム—

Abstract

Large-scale igneous activity characterised the development of the Carpathian-Pannonian Region, Central Europe from Late Cretaceous to Pleistocene times, with a peak of activity during the Miocene. The magmatism is considered to have been caused by the closure of the Tethys Sea and consequent collision between the African and Eurasian plates, but the exact mechanism for magmageneration is still a matter of debate. In order to get a better understanding of magmageneration and differentiation processes, a new set of bulk chemical data, including trace and rare earth elements has been presented on igneous rocks from the NE part. Together with published data, igneous rocks from the three regions of the research area (Tokaj-Slanske Mts., Great Plain and Transcarpathia) cover a wide spectrum of the calc-alkaline series and reveal close similarities in both petrography and geochemistry. No significant spatial differences could be revealed in terms of major element chemistry but Nb and Zr trends slightly differ in Tokaj-Slanske Mts. -Great Plain and Transcarpathia. Felsic rocks formed mainly at the earlier stages, the most mafic sample at the latest stage of the igneous activity. Alkali basaltic activity (generally characterising the development of the Carpathian-Pannonian Region from 11.7 Ma) has not been observed at the NE part. The results of crystallization and mixing calculations on igneous rocks from the area of research show that geochemical characteristics of most rocks cannot be explicitly explained by crystallization processes alone and they reflect the involvement of various (upper crustal, lower crustal, upper mantle and alkali basaltic) source materials through magma mixing, assimilation and contamination. The different spatial Nb and Zr trends may be interpreted as the outcome of mainly crustal contamination in the case of rocks from Transcarpathia, as opposed to the joint effects of upper crustal contamination and the involvement of alkali basaltic magma in the case of rocks from the Tokaj-Slanske Mts. Thus, alkali basaltic magma may have been involved in the formation of calc-alkaline igneous rocks not only as heat source, but in the case of basaltic rocks, also as material.