Combined analysis of faults and deformation bands reveals the Cenozoic structural evolution of the southern Bükk foreland (Hungary)

摘要

A combination of fault slip data and deformation band analysis allows the separation of 8 deformation phasesud(D1–D8) in the southern foreland of the Bükk Mts., NE Hungary. The newly defined D1 phase is characterisedudby NE–SW compression which is hard to integrate into the Cenozoic evolution of the area. The D2a is also audnew stress state which was a NE–SW syn-sedimentary extension of Late Oligocene age. The coeval D2b stressudstate is characterised byNW–SE compression andwas responsible for the (partly syn-sedimentary) tilting and erosionudof the Oligocene sediments during Late Oligocene to earliest Miocene. D3 corresponds to E–Wcompression andudperpendicular extension. Itwas followed by NE–SW (D4) andWNW–ESE extension (D5) which corresponds to theudmain rifting phases of the Pannonian Basin system from the late Early to Mid-Miocene (17.3–15Maand 15–11.6 Ma,udrespectively). It was interrupted by a short inversion (D6) of NE–SW to ENE–WSW compression at latest Mid-udMiocene to earliest Late Miocene. Extension and major tilting were renewed in the early Late Miocene (D7). D8udshows NW–SE compression during latest Miocene to Pliocene when the Bükk Mts. started to be uplifted.udDeformation bands were formed during several of the established tectonic phases. Combined analysis of deformationudbands and fault slip data permitted the unraveling of the evolution of deformation bands in connectionudwith deformation mechanism, burial depth and cumulative displacement. We suggest that the less destructiveudtype of deformation bands is the oldest ones, and were formed at the shallowest burial and accumulated theudsmallest total displacement. The more cataclastic the deformation bands are, the greater the total displacementudand deeper burial depth that can be observed. With progressive burial and/or displacement, deformationudbands evolved into discrete fault slip surface.