The Glaciation of Gondwana

Regardless of the assumed temperature, the water from which the calcite cleats in the Allan Hills formed was depleted in 0 compared to seawater - 0%o) or meteoric water in the midlatitudes 8%o). The other calcite cleats 

The water which formed the calcite cleats in the Permian coal deposits of southern Victoria Land is depleted in 0 almost as much as the water that formed the carbonate rocks in the Permian sandstones and shales in the central Transantarctic Mountains (Table 11.2). Therefore, the cleats may have formed during the Permian Period in glacial meltwater that was depleted in 0. Alternatively, the cleats could have formed much more recently from meltwater of the present-day snow adjacent to the Transantarctic Mountains which also has 5 0 values between -20%oand-30%o on the SMOW scale. The age of the calcite cleats in the Permian coal of the Transantarctic Mountains is presently unknown. 

The most recent continental glaciation which occurred during the Pleistocene may not yet have ended. For example, Carlson et al. (2008) have recently modeled the disintegration of the Laurentide ice sheet of North America and Siddall and Kaplan (2008) 

The observations by Coates (1985) were confirmed and elaborated by Isbell et al. (2008) in the most recent summary of the Permian glaciation of the Transantarctic Mountains. The cross-section of Isbell et al. (2008) drawn parallel to the strike of the Transantarctic Mountains in Fig. 11.5 clearly shows the thinning of the tillite in the Queen Maud Mountains and the thickening of the section in the areas of the Beardmore-Nimrod glaciers and in the Ohio Range. 

Cross-Section of Permian Tillites in the Transantarctic Mountains 

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Although Powell and Veevers (1987) attributed the start of the glaciation of Gondwana to uplift during the Early Carboniferous in Australia and South American, the major cause was climate change resulting from the... 

According to this sequence of events, the glaciation of Gondwana passed through three episodes which are identified in Fig. 11.7 based on the work of Veevers and Powell (1987). Episodes I and II consisted of alpine glaciations in South America (Brazil) and adjacent areas of Africa. Episode III was the major glaciation of Gondwana by a continental ice sheet. Part A of... 

Fig. 11.7 The glaciation of Gondwana occurred primarily because parts of this large continent moved across the south geographic pole of the Earth from the Late Devonian to Early Permian. After two initial episodes of alpine glaciation (I and II) in the area of what is now South America, a large continental ice sheet (IIIA) developed during the Early Carboniferous (i.e., Mississippian) and spread across a large area of Gondwana including territories that are today South Africa, Australia,...

These considerations remind us that the Transantarctic Mountains did not exist during the Permian glaciation of the East Antarctic craton and that the eventual uplift of the mountains may have between initiated by large-scale rifting of Gondwana which was accompanied by the eruption of flood basalts during the Jurassic Period. 

Schmidt DL, Ford AB (1966) Geology of the northern Pensacola Mountains and adjacent areas. Antarctic J US 1(4) 125 Schmidt DL, Ford AB (1969) Geology of the Pensacola and Thiel Mountains. In Craddock C et al. (eds) Geologic maps of Antarctica. Antarctic Map Folio Series, Sheet 5, Folio 12. American Geographical Society, New York Schmidt DL, Williams PL (1967) Continental glaciation of late paleozoic age, Pensacola Mountains, Antarctica. In, AJ Amos, ed., Gondwana Stratigraphy, 2 91-106. UNESCO, Paris... 

Fig. 9.2 The regional distribution of Permian tillite on the southern continents and the ice-flow directions indicate the size of the Permian ice sheets when the continents are reassembled into Gondwana. This interpretation also indicates that Gondwana broke up after the Permian glaciation and that the continental fragments subsequently drifted to their present positions on the southern hemisphere of the Earth (Adapted from Smith (1992) based on the reconstruction by du Toit (1937))...

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