Combined titanite and apatite fission-track data from Gjelsvikfjella, East Antarctica – another piece of a concealed intracontinental Permo-Triassic Gondwana rift basin?

Abstract

Abstract Titanite and apatite fission-track ages from Gjelsvikfjella and the eastern Mühlig–Hofmann Mountains, East Antarctica, range between 516±50 and 323±30 Ma and 366±16 and 186±9 Ma, respectively. The thermochronological data set indicates differential cooling of two tectonic blocks (Hochlinfjellet–Festninga and Risemedet). Inverse modelled time–temperature paths suggest that the Hochlinfjellet–Festninga block cooled at first below 60 °C during the mid-Palaeozoic, whereas the Risemedet block cooled during the earliest Triassic. Differential cooling is most probably related to physical separation along active faults, which is associated with Gondwana-wide intracontinental rifting. This tectonic activity shaped the landscape in the study area along structures running perpendicular to the continental margin of Dronning Maud Land. A rift locus was possibly located along the Penck–Jutul graben west of the study area. In contrast to other parts of Dronning Maud Land, Jurassic magmatism and initial break-up between East Africa and East Antarctica did not influence the apatite FT data. Modelled apatite fission-track data indicate the onset of final cooling since the Early Cretaceous, suggesting post-Cretaceous unroofing of the palaeosurfaces in eastern Dronning Maud Land.