Ellsworth-Whitmore Mountains

The only exception are the aplogranites and microgranites of the Haag Nunataks (77°00 S, 078°18 W) in 

West Antarctica which crystallized at 1058 53 and 1003 18 Ma, respectively. A similar whole-rock Rb-Sr date of 980 16 Ma (recalculated to /V = 1.42 x 10 year ) was reported by Eastin and Faure (1971) for rhyolites in the Littlewood and Bertrab nunataks at 77°53 S, 034°10 W in Coats Land on the east coast of the Weddell Sea (Section 9.4). However, the relationship between the Haag Nunataks and the small nunataks of Coats Land can only be understood in the context of the rifting of Rodinia and the departure of Laurentia which are the subjects of Chapter 9. 

The Ellsworth Mountains of West Antarctica in Eig. 8.4 are composed of a thick sequence of highly folded and low-grade metasedimentary and metavolcanic rocks which range in age from Proterozoic to Permian (Craddock et al. 1964a, 1986 Craddock 1969 a Schopf 1969 Webers et al. 1992). Although volcanic rocks do occur in the Heritage Group of Neoproterozoic 

The Thiel Mountains are part of the far-eastern mountains that extend from the Ohio Range of the HorUck Mountains to the east coast of the WeddeU Sea. The rocks exposed along the north-facing escarpment of the Thiel Mountains consist of undeformed sedimentary rocks of low metamorphic grade (Mt. Walcott Formation) that are overlain by the cordierite-bearing hypersthene-quartz-monzonite porphyry of the Thiel Mountains Porphyry. This unit is a massive deposit of crystal-rich silicic tuff that contains cordierite and hypersthene as xenocrysts and in small granuhte xenoliths. The presence of cordierite in this volcanic or shallow intrusive 

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The SWEAT hypothesis of Moores (1991) also positions the Haag Nunatak, which is presently located close to the crustal block of the Ellsworth-Whitmore Mountains (Section 8.1.3), within the Grenville belt in the gap between Coats Land and the Yavapai-Mazatzal province of North America in Fig. 9.6. In this way, the Haag Nunatak has found a home that is consistent with... 

Antarctica increases stepwise from about 20 to 40 km in West Antarctica, to 40-50km under the Transantarctic Mountains (TAM), and to more than 60 km under the Gamburtsev Mountains (GM). The principal exceptions in West Antarctica are the Ellsworth-Whitmore Mountains (EWM) and Marie Byrd Land (MBL) where the thickness of the crust rises to more than 40 km. The crustal thickness under the Transantarctic Mountains rises abruptly from 35 to about 45 km which suggests that this boundary is a fault zone or crustal suture. 

This rift system in Fig. 15.16 enters northern Victoria Land from the Indian Ocean and runs parallel to the Jurassic rift system in Fig. 15.12 (Schmidt and Rowley 1986) as far as the Horlick Mountains, where it turns and passes west of the Ellsworth-Whitmore mountains... 

Fig. 15.5 West Antarctica is a mosaic of several crustal fragments that are arranged about the Byrd Subgladal Basin, the bedrock surface of which is below sea level. The crustal fragments include the Ellsworth-Whitmore Block, EiUsworth Land, Thurston Island, the Jones Mountains, and Marie Byrd Land. The Byrd Subglacial Basinis roughly parallel to the Transantarctic Mountains and their extension to the Thiel and Pensacola mountains. The line A-B is the approximate position of the cross section of the subduction zone on the paleo-Pacific coast of Gondwana in Fig. 15.6 (Adapted from Elliot (1974) and LeMasuiier (2008))...

Antarctica at this time the Antarctic Peninsula, the Ellsworth Mountains, the Whitmore Mounteiins, Thurston Island, Marie Byrd Land, the North and South islemds of New Zealand, and Tasmania (Adapted from Lawver and Scotese (1987))... 

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