Neogene and Quaternary Volcanism of the Carpathian-Pannonian Region: Changes in Chemical Composition and lts Relationship to Basin Formation

This chapter presents a statistical evaluation of the chemical variation in space and time of the Miocene-Quaternary volcanism of the Carpathian-Pannonian region. Three main genetic types of this volcanism can be distinguished as follows: (1) during Karpatian to late Pliocene time intermediate, mainly andesitic, stratovolcanic complexes formed; (2) acidic (mainly ignimbritic) volcanism developed in the inner part of the Pannonian basin from the Eggenburgian-Ottnangian boundary to late Sarmatian time, which partly overlaps the intermediate volcanism and; (3) alkali basaltic volcanism occurred in Pannonian to Quaternary time. The data presented here show that the intermediate lavas became significantly more acidic from Karpatian to late Sarmatian time. At the Sarmatian-Pannonian boundary there was an 257 abrupt change and in early Pannonian time the intermediate lavas which erupted were much more basic. The K20 content of the intermediate lavas also increased from Karpatian to late Sarmatian time. This suggests that at the Sarmatian Pannonian boundary a significant change may have taken place in the tectonics of the region. The data presented in this chapter suggest that volcanism in the Pannonian basin can be largely explained by a mantle diapir model with related melting of crustal rocks. They further indicate that in the East Carpathians, volcanism may be largely related to the presence of a subducted slab. The geochemical data indicate that the main period of mantle diapirism lasted until the end of Sarmatian time, when very fast subsidence began in the Pannonian basin