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 b odies are used to constrain the low-temperature (i.e. sub approximatel y 110-degrees-C) thermal history of the northern Prince Charles Mounta ins, East Antarctica. Two discrete phases of cooling have been identif ied, both of which are attributed to regional exhumation associated wi th rifting episodes. A phase of late Palaeozoic cooling, that began du ring the Carboniferous, is inferred to have been associated with the i nitial formation of the Lambert Graben. A more recent phase of cooling was initiated during the Early Cretaceous and is estimated to have lo cally involved the removal of at least 2 km of material using an assum ed palaeotemperature gradient of approximately 25-degrees-C km-1 at th e time of cooling. This latter phase of exhumation was closely accompa nied by the emplacement of a variety of mafic alkaline rocks at ambien t palaeotemperatures less than approximately 60-degrees-C and was prob ably related to renewed extension of the Lambert Graben during the bre ak-up of eastern Gondwana. The results of this study suggest that fina l exhumation of high-grade Precambrian basement of the northern Prince Charles Mountains was largely controlled by Phanerozoic rifting event s.