PHANEROZOIC EXHUMATION HISTORY OF NORTHERN PRINCE-CHARLES-MOUNTAINS (EAST ANTARCTICA)

Apatite fission-track data from samples of Precambrian basement, Late Permian-Triassic sedimentary rocks and inferred Cretaceous intrusive bodies are used to constrain the low-temperature (i.e. sub approximately 110-degrees-C) thermal history of the northern Prince Charles Mountains, East Antarctica. Two discrete phases of cooling have been identified, both of which are attributed to regional exhumation associated with rifting episodes. A phase of late Palaeozoic cooling, that began during the Carboniferous, is inferred to have been associated with the initial formation of the Lambert Graben. A more recent phase of cooling was initiated during the Early Cretaceous and is estimated to have locally involved the removal of at least 2 km of material using an assumed palaeotemperature gradient of approximately 25-degrees-C km-1 at the time of cooling. This latter phase of exhumation was closely accompanied by the emplacement of a variety of mafic alkaline rocks at ambient palaeotemperatures less than approximately 60-degrees-C and was probably related to renewed extension of the Lambert Graben during the break-up of eastern Gondwana. The results of this study suggest that final exhumation of high-grade Precambrian basement of the northern Prince Charles Mountains was largely controlled by Phanerozoic rifting events.