Uplift History of the Prince Charles Mountains and the East Antarctic Shield

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From the abstracts of the two referenced papers:

Antarctica's Lambert graben, Australia's North West Shelf, and the eastern Indian Peninsula all host thick, fault-bounded Permian-Triassic successions. These terranes were adjacent to each other in Gondwana. The Lambert graben intersects the modern coastline, strikes oblique to shelf architecture, and has a geophysical signature that can be traced greater than 1000 km inland. Vitrinite reflectance data from the graben margins record Permian-Triassic infill. Australia's North West Shelf is the relict of an intracontinental Carboniferous-Permian rift that was infilled during the Permian-Triassic then driven to oceanic completion during Jurassic-Cretaceous Gondwana breakup. This rift was compartmentalised over length scales of ~650 km, corresponding to accommodation zones, margin-normal geophysical lineaments, and long-lived crustal weaknesses. In eastern India, similar compartmentalisation is marked by extensive coal-bearing graben systems. Gondwana reconstructions indicate that the Lambert graben corresponds to the orientation and length scale of Carboniferous_Permian rift compartmentalisation. The Lambert graben represents an accommodation zone of a wide intracontinental rift that extended from Australia's North West Shelf, between India and Antarctica, to southern Africa. This rift collected Gondwana's thick Permian-Triassic sedimentary blanket and rich alluvial coal deposits.

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 (ie sub ~110 degree 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 ~25 degrees C per km 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 ~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.

Lineage

Progress Code: completed

Statement: Values provided in temporal and spatial coverage are approximate only.