DUDE WANT TO KNOW THE CONTIENTAL DRIFT

The reconstruction of Laurentia, Australia, and Antarctica into a Proterozoic supercontinent is evaluated by analyzing the fit of Precambrian provinces defined by isotopic and geochronologic mapping. The analysis is complicated by allochthonous segments of the Antarctic and eastern Australian margins. Removal of the allochthonous provinces produces a closer fit of the continents; there is a match of Early Proterozoic basement between southwestern Laurentia and the only exposure of craton known from the paleo-Pacific margin of Antarctica. In addition, western Laurentia is brought closer to the Australian Gawler block, consistent with provenance interpretations of the Belt Supergroup. Removal of the allochthonous provinces by right-lateral translation relative to the Antarctic craton margin places them in a pre-750 Ma position where they could be southwestward extensions of the Yavapai-Mazatzal and Grenville provinces of southern Laurentia. This modified reconstruction leads to a prediction of extensive Archean basement in Antarctica between the South Pole and Victoria Land, a prediction partly borne out by Archean rocks in the Miller Range of the Transantarctic Mountains; it also predicts the presence of 1.4 Ga rapakivi granites in the Transantarctic Mountains basement. This configuration implies assembly of the Australia-Antarctica Gondwana margin by terrane accretion following, or accompanied by, left-lateral translation. This is compatible with a tectonic regime of clockwise rotation of Laurentia relative to Australia and Antarctica after rifting. Thus, the proposed supercontinent, with some modifications, has potential for explaining several aspects of the pattern of Precambrian provinces in the three continents.

GEOLOGICAL HISTORY AND PALEONTOLOGY

Below you will find a collection of photos that illustrate different glacial environments, processes, sediments and landforms. Most of the photos are mine, and you are free to use them for educational purposes













More than 170 million years ago, Antarctica was part of the supercontinent Gondwana. Over time Gondwana broke apart and Antarctica as we know it today was formed around 25 million years ago.

Paleozoic era (540-250 Mya)


Survey route.
During the Cambrian period, Gondwana had a mild climate. West Antarctica was partially in the northern hemisphere, and during this period large amounts of sandstones, limestones and shales were deposited. East Antarctica was at the equator, where sea-floor invertebrates and trilobites flourished in the tropical seas. By the start of the Devonian period (416 Mya) Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. Sand and silts were laid down in what is now the Ellsworth, Horlick and Pensacola Mountains. Glaciation began at the end of the Devonian period (360 Mya) as Gondwana became centered around the South Pole and the climate cooled, though flora remained. During the Permian period the plant life became dominated by fern-like plants such as Glossopteris, which grew in swamps. Over time these swamps became deposits of coal in the Transantarctic Mountains. Towards the end of the Permian period continued warming led to a dry, hot climate over much of Gondwana
Mesozoic era (250-65 Mya)


Bransfield Strait.
As a result of continued warming, the polar ice caps melted and much of Gondwana became a desert. In East Antarctica the seed fern became established, and large amounts of sandstone and shale were laid down at this time. The Antarctic Peninsula began to form during the Jurassic period (206-146 Mya), and islands gradually rose out of the ocean. Ginkgo trees and cycads were plentiful during this period, as were reptiles such as Lystrosaurus. In West Antarctica conifer forests dominated through the entire Cretaceous period (146-65 Mya), though Southern beech began to take over at the end of this period. Ammonites were common in the seas around Antarctica, and dinosaurs were also present, though only two Antarctic dinosaur species (Cryolophosaurus and Antarctopelta) have been described to date. It was during this period that Gondwana began to break up.
Geology of present-day Antarctica


The geological study of Antarctica has been greatly hindered by the fact that nearly all of the continent is permanently covered with a thick layer of ice. However, new techniques such as remote sensing have begun to reveal the structures beneath the ice.
Geologically, West Antarctica closely resembles the Andes of South America.[1] The Antarctic Peninsula was formed by uplift and metamorphism of sea-bed sediments during the late Paleozoic and the early Mesozoic eras. This sediment uplift was accompanied by igneous intrusions and volcanism. The most common rocks in West Antarctica are andesite and rhyolite volcanics formed during the Jurassic Period. There is also evidence of volcanic activity, even after the ice sheet had formed, in Marie Byrd Land and Alexander Island. The only anomalous area of West Antarctica is the Ellsworth Mountains region, where the stratigraphy is more similar to the eastern part of the continent.
East Antarctica is geologically very old, dating from the Precambrian era, with some rocks formed more than 3 billion years ago. It is composed of a metamorphic and igneous platform which is the basis of the continental shield. On top of this base are various more modern rocks, such as sandstones, limestones, coal and shales laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains. In coastal areas such as Shackleton Range and Victoria Land some faulting has occurred.
The main mineral resource known on the continent is coal. It was first recorded near the Beardmore Glacier by Frank Wild on the Nimrod Expedition, and now low-grade coal is known across many parts of the Transantarctic Mountains. The Prince Charles Mountains contain significant deposits of iron ore. The most valuable resources of Antarctica lie offshore, namely the oil and natural gas fields found in the Ross Sea in 1973. Exploitation of all mineral resources by signatory states is banned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty.
Abstract
We present and discuss a new model of the crust and upper mantle at high southern latitudes that is produced from a large, new data set of fundamental mode surface wave dispersion measurements. The inversion for a 2° × 2° shear velocity model breaks into two principal steps: first, surface wave tomography in which dispersion maps are produced for a discrete set of periods for each wave type (Rayleigh group velocity, 18–175 s; Love group velocity, 20–150 s; Rayleigh and Love phase velocity, 40–150 s) and, second, inversion for a shear velocity model. In the first step, we estimate average resolution at high southern latitudes to be about 600 km for Rayleigh waves and 700 km for Love waves. The second step is a multistage process that culminates in a Monte Carlo inversion yielding an ensemble of acceptable models at each spatial node. The middle of the ensemble (median model) together with the half width of the corridor defined by the ensemble summarize the results of the inversion. The median model fits the dispersion maps at about the measurement error (group velocities, 20–25 m/s; phase velocities, 10–15 m/s) and the dispersion data themselves at about twice the measurement error. We refer to the features that appear in every member of the ensemble as “persistent.” Some of persistent features are the following: (1) Crustal thickness averages ∼27 km in West Antarctica and ∼40 km in East Antarctica, with maximum thicknesses approaching 45 km. (2) Although the East Antarctic craton displays variations in both maximum velocity and thickness, it appears to be a more or less average craton. (3) The upper mantle beneath much of West Antarctica is slow and beneath the West Antarctic Rift is nearly indistinguishable from currently dormant extensional regions such as the western Mediterranean and the Sea of Japan. Our model is therefore consistent with evidence of active volcanism underlying the West Antarctic ice sheet, and we hypothesize that the West Antarctic Rift is the remnant of events of lithospheric rejuvenation in the recent past that are now quiescent. (4) The Australian-Antarctic Discordance is characterized by a moderately high velocity lid to a depth of 70–80 km with low velocities wrapping around the discordance to the south. There is a weak trend of relatively high velocities dipping to the west at greater depths that requires further concentrated efforts to resolve. (5) The strength of radial anisotropy (v sh − v sv )/v sv in the uppermost mantle across the Southern Hemisphere averages ∼4%, similar to the Preliminary Reference Earth Model. Radial anisotropy appears to be slightly stronger in West Antarctica than in East Antarctica and in the thinner rather than the thicker regions of the East Antarctic craton.
Glacial geology photos