Neogene and Quaternary Volcanism of the Carpathian–Pannonian Region: Changes in Chemical Composition and Its Relationship to Basin Formation
Published:January 01, 1988
T. Póka, 1988. "Neogene and Quaternary Volcanism of the Carpathian–Pannonian Region: Changes in Chemical Composition and Its Relationship to Basin Formation", The Pannonian Basin: A Study in Basin Evolution, Leigh H. Royden, Ferenc Horváth
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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 abrupt change and in early Pannonian time the intermediate lavas which erupted were much more basic. The K2O 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.
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The Pannonian Basin: A Study in Basin Evolution
The Pannonian basin system is an integrap part of the Alpine mountain belts of east-central Europe. It is completely encircled by the Carpathian Mountains to the north and east, the Dinaric Alps to the south, and the Southern and Eastern Alps to the west. In 1912, Kober defined the Pannonian basin as one of the type “Zwischengebirge,” a relatively un-deformed region characterized by block faulting and situated between externally vergent thrust belts. More recent studies using subsurface data have shown that the Pannonian area was extensively deformed by Mesozoic thrusting and subsequently disrupted by a complex system of Cenozoic normal and wrench faults. Thus, the Pannonian “massif” has undergone several types of deformation, which are partly hidden by a thick sequence of sedimentary rocks of Neogene-Quaternary age. The Pannonian basin is actually a system of small, deep basins separated by relatively shallow basement blocks. The Neogene-Quaternary sedimentary rocks exceed 7 km in thickness in some areas, and the basin system (including the Transylvanian basin) is about 400 km from north to south and 800 km from east to west. It is currently interpreted by most workers as a Mediterranean back arc extensional basin of the middle Miocene age. The Carpathians, Eastern Alps, and Dinarides, which surround the Pannonian basin, are the result of Mesozoic and Cenozoic continental collision between Europe and several continental fragments to the south, including Africa. Thrusting was direted outward from the present Pannonian basin toward the European platform and the Adriatic region. In all the orogenic belts, the interior parts of the thrust belts were deformed in Mesozoic time, while the outer parts were deformed in Tertiary time. The volume presents 26 papers and eight regional maps resulting from a joint five-day symposium held in Veszprem, Hungary, in 1982 entitled “Evolution of Extensional Basins within Regions of Compression with Emphasis on the Intra-Carpathian Region.” The symposium was sponsored jointly by the Hungarian Oil and Gas Trust, the Hungarian Geological Survey, and the U.S. National Science Foundation.