Thermal and denudation history of the Lusatian Block (NE Bohemian Massif, Germany) as indicated by apatite fission-track data

Abstract

Abstract The Lusatian Block in eastern Germany is part of the Variscan Bohemian Massif. It is located at the intersection of two regional fault–thrust systems that have been controlling the regional geological and landscape evolution since at least late Mesozoic times, the Elbe Fault System and the Eger Graben. Although the Lusatian Block has traditionally been described as a morphological high throughout the Mesozoic, timing, style and amount of denudation have not yet been quantified. Apatite fission-track (AFT) analysis of basement rocks yields ages varying between approximately 70 and 95 Ma, with mean track-lengths ranging from 13.6 to 14.1 µm. Thermal history modelling of the AFT data points to a minimum denudation of 3 km of the Lusatian Block in the Late Cretaceous. Onset of denudation can be related to transpression along the Lusatian Thrust as a main element of the Elbe Fault System. Moreover, the thermal history models provide tentative evidence for a second cooling–denudation event, which affected Lusatia in the late Palaeogene. This final denudation of at least 1 km probably occurred as a far-field response to the uplift of the northern shoulder of the Cenozoic Eger Graben.