Late Paleozoic Glaciation: Part III, Antarctica
Like other Gondwanaland fragments, Antarctica was glaciated during the late Paleozoic, as demonstrated by striated floors and boulder pavements and by glacially striated clasts in diamictites and associated varvelike strata. Tillites are known throughout the Transantarctic Mountains from the vicinity of Ross Island to the Pensacola Mountains, as well as in the Ells-worth Mountains in West Antarctica. These strata apparently were laid down in three basins (Ellsworth-Pensacola basin, Horlick-Queen Maud basin, and Beard more basin). Ice flowed into the Ellsworth-Pensacola basin from a major center located in the region of the eastern Weddell Sea, possibly beginning in the early Carboniferous. The Thiel salient, separating the Ellsworth-Pensacola and Horlick-Queen Maud basins, yielded some debris northward into the former basin but served primarily as a major gathering ground for ice which flowed westward into the Horlick-Queen Maud basin. Similarly, the western Queen Maud Mountains, where tillites are thin or absent, was a local center for ice flowing eastward into the Horlick-Queen Maud basin and probably westward into the Beardmore basin, although the latter direction is not yet proven by striae patterns. A major center of ice accumulation also seems to have existed in northern Victoria Land, whence flow was toward the southeast. The Ellsworth-Pensacola basin was a continuously depressed Paleozoic downwarp of major proportions, whereas the Permian Horlick-Queen Maud and Beard-more basins were shallow depressions and possibly connected. The center of late Paleozoic glaciation may have migrated across Antarctica from the Wed-dell Sea region (early Carboniferous) to northern Victoria Land (Permian), judging from the meager paleontological data and stratigraphic considerations. This would be in keeping with the relative-motion curves of the paleomagnetic poles for the reconstructed Gondwana-land fragments of South America, Africa, and Antarctica, the late Paleozoic segments of which cross Antarctica from the Weddell Sea to Victoria land.