Tertiary cooling and exhumation history in the Maramures area (internal eastern Carpathians, northern Romania) : thermochronology and structural data

The Tertiary kinematic history of the Maramures area is constrained by integrating thermochronological (fission track and (UTh)/He analysis) data with field-based structural investigations. This study focuses on the tectonic evolution of the northern rim of the Tisza Dacia block during collision with the European margin. Cretaceous nappe stacking, related metamorphism as well as Late Cretaceous exhumation are evidenced by zircon fission track data. Subsequent Palaeogene to Early Miocene sedimentation led to burial heating and annealing of fission tracks in apatite. Final tectonic uplift was initiated during the convergence of Tisza Dacia with the European margin, associated with transpressional deformation (16 to 12 Ma). This led to Mid-Miocene exhumation, recorded by apatite fission track cooling ages in the western part of the study area. Transtension between 12 and 10 Ma caused brittle deformation along EW trending strike-slip faults and SWNE trending normal faults, delimiting blocks that were tilted towards the SW. This fragmentation of the crust led to enhanced exhumation at rates of 1 mm/a in the central part of the study area, as is documented by Middle to Late Miocene cooling ages (13 to 7 Ma). The outside estimate for the total amount of exhumation since Middle Miocene times is 7 km.