Geochronology

Antarctica has had a long and complex geological history, much of which has in one way or another had some effect on the formation of the Transantarctic Mountains. The many stages of deformation have led to a great deal of debate over the true history of Antarctica, what follows is a summary of current thinking.

Precambrian

Much of the Antarctic craton was formed in the Precambrian by a series of orogenic events (this can be viewed as an animation):

 Napier orogeny (4000 ± 200 Ma) - Formed the cratonic nucleus (map)

 Rayner orogeny (~ 3500 Ma) - Thickened the cratonic nuclei (map)

 Humboldt orogeny (~ 3000 Ma) - Deformation of gently dipping strata (map)

 Insel orogeny (2650 ± 150 Ma) - Extensive reworking of old crust (map)

 Early Ruker orogeny (2000 - 1700 Ma) - Deformation and Greenschist-facies metamorphism (low-grade, T = 300 - 500 ° C) (map)

 Late Ruker / Nimrod orogeny (1000 ± 150 Ma) - Widespread plutonism and further metamorphism (map)

 Beardmore orogeny (633 - 620 Ma) - Compressional or convergent (first stage of formation of the TAM) (no map available, not really different than the Nimrod orogeny)

Early Palaeozoic

Gondwana moved southward during the early Palaeozoic (Western Africa lay over the South Pole at this time) and during the Early Cambrian Antarctica was mostly covered by an epicontinental sea. Volcaniclastics, shallow marine clastics, platform carbonates and deepwater turbidites were deposited. The Ross Orogeny (~ 500 Ma) then caused further deformation (and Granitic intrusions) as subduction occurred on the palaeo-Pacific margin of the Eastern Craton.

Middle Palaeozoic

Gondwana had by now shifted into a fully polar position, East Antarctica was mostly a continental environment and late in the Devonian the Pole was located in South America. Silurian-Devonian age rocks outcrop in the TAM and compose the Taylor and Victoria Groups, which form the Beacon Supergroup.

Late Palaeozoic

In the Late Palaeozoic Antarctica moved into a polar position as Gondwana, now joined with Laurasia, formed Pangea. Deposits indicate a submerged and occasionally ice covered continent at this time, with marine and continental sediment being deposited. In the late Permian the ice sheet receded and an extensive inland sea was formed.

Mesozoic

The Permian-Triassic boundary marks the breakup of Pangea, though Gondwana remained relatively intact. Continental conditions still prevailed, but marine deposits are also recorded (in the Trinity Peninsula group & Legoupil Formation). Moving into the Jurassic and Early Cretaceous global tectonic activity continued with the breakup of Pangea and the start of Gondwana breakup. Associated massive volcanism also occurred (particularly in the Jurassic when rifting began). Remarkably little sediment is found of this age (marking the begininning of uplift and domination of erosion). In the late Cretaceous seperation continued as most of the world's (current) oceans began to form and grow. Large sedimentary successions are found marking the rapid subsidence of bark-arc basins.

Tertiary

Antarctica's margins were fully developed by the late Tertiary and generally Antarctica had a colder climate (now fully surrounded by cold sea rather than warm land). Deposition of continental deposits still continued and periods of basaltic volcanism are recorded. Rifting finally ended in the tertiary, though exactly when is still debated.

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