Combined apatite fission-track and single grain apatite (U-Th)/He ages from basement rocks of central Dronning Maud Land (East Antarctica) - Possible identification of thermally overprinted crustal segments?

Two thermally undisturbed vertical profiles are used to record the long-term cooling history of central Dronning Maud Land. Time-temperature paths derived from modelled apatite FT data of these profiles revealed two phases of accelerated cooling during the Late Carboniferous and the Early Jurassic. Both phases are followed by slow cooling which is also documented by the spread in apatite (U-Th)/He single grain ages. The cooling at the end of the Carboniferous is most probably related to far field effects associated to the prevailing convergent tectonics. During the initial separation between East Antarctica and Mozambique erosion along an evolving rift shoulder caused the Jurassic cooling. Denudation of the basement was simultaneous with volcanism with both pre-dating (c. 20-10 Ma) sea-floor spreading in the Riser Larsen Sea (c. 155 Ma). Post Jurassic cooling was restricted to the lowest temperature sensitivity of both methods. Combined inverse modelled apatite FT data and forward modelled (U-Th)/He data suggest an Eocene/Oligocene cooling step, possibly related to the flexural-isostatic response to the development of ice-sheets.