Contrasting metamorphic and post-metamorphic evolutions within the Algyő basement high (Tisza Mega-unit, SE Hungary). Consequences for structural history

Abstract The Algyő High (AH) is an elevated crystalline block in southeastern Hungary covered by thick Neogene sediments. Although productive hydrocarbon reservoirs are found these sequences, numerous fractured also occur the pre-Neogene basement of Pannonian Basin. Based on analogies, rock body AH might play a key role fluid storage and migration; however, its structure therefore reservoir potential little known. comprehensive petrologic study conjunction with analysis spatial position major lithologies, considered to have been assembled from blocks different petrographic features metamorphic history. most common lithologies garnet-kyanite gneiss mica schist associated garnetiferous amphibolite dominant northwestern parts AH. first regional facies metamorphism was overprinted contact (metasomatic) event during decompression stability field kyanite. Garnet-bearing experienced peak conditions comparable host gneiss. Regarding similarities features, area represent disaggregated same body. central part characterized epidote gneiss-dominated metamorphosed along greenschist-facies retrograde pathway as well chlorite schist-dominated formed progressive metamorphism. independent evolution two further confirmed presence propylitic overprint schists. northwestern, probably became juxtaposed post-metamorphic normal faults developed due extensional processes. supposed brittle structural boundaries between could provided migration pathways adjacent over-pressured sub-basins, or even suitable reservoirs.