Start Ordovician radiometric dating

Ordovician radiometric dating

Some other areas like Bowers Terrane and Robertson Bay Terrane display remarkable Ordovician outcrops.

(2002) for the Proterozoic and early Paleozoic where these authors stablished interesting links with the fauna and environmental evolution of the paleocontinents of Gondwana and Laurentia.

In the Thiel, Horlick and Queen Maud Mountains, the sequences contain prominent silicic volcanics, giving a Rb-Sr whole rock isochron of 502 6 Ma in the Thiel Mountains (Pankhurst et al., 1988) and a whole-rock Rb-Sr age of 483 9 (recalculated) in the western Queen Maud Mountains (Faure et al., 1979), dating the volcanism as close to the Cambro Ordovician boundary.-Ross Orogeny in the Transantarctic Mountains During late Cambrian Early Ordovician times, the entire length of the Transantarctic Mountains from the Shackleton Range to northern Victoria Land experienced uplift, folding and metamorphism (Ross Orogeny) and, over most of the region, intrusion by calc-alkaline granitoid plutons (Granite Harbour Intrusives).

The Ross orogeny has been interpreted as a cratonization even associated with an east-dipping subduction zone along the paleo Pacific margin of Antarctica (Stump, 1982, Borg, 1983, Schmidt, 1983 and Borg et al., 1987).

Marie Byrd Land and much of northern Victoria Land formed part of another, contrasting probably allochtonous province.

In the Transantarctic Mountains, from Byrd Glacier to the Shackleton Range, lower Paleozoic rocks from two unconformity sequences.

The group consists dominantly of feldespathic sandstone with subordinate grit and conglomerate beds inferred to have been deposited under terrestrial-deltaic conditions (Clarkson, et al., 1979).

A Rb-Sr isochron age of 475 40 Ma (early Ordovician) is presumed to reflect diagenesis of the sediments soon after deposition (Pankhurst et al., 1983).

En el Territorio Antrtico, el Ordovcico ha sido reconocido en localidades en el mbito de los Montes Transantrticos, el denominado orgeno de Ross o Sistema de Ross dentro del sector reclamado por la Repblica Argentina y en reas cercanas tales como los montes Ellsworth.