La Gorce Mountains

Granite Harbor Intrusives Granite Harbor Intrusives Intrusive Contact Granite Harbor Intrusives 

Beardmore Ackerman Wyatt La Gorce Base not exposed  

Stump (1986) is supported by the occasional presence of apatite, rutile, corundum, kyanite, and tourmaline. Stump (1995) also noted that the La Gorce Formation differs from the Goldie Formation of the central Transantarctic Mountains (Section 5.2) by the absence of carbonate beds except for calcite veins near faults. 

Wyatt Formation near Mt. Wyatt on the west side of the Scott Glacier (Fig. 6.12). 

The mineral composition (mode) of the Wyatt Formation in the Scott-Glacier area was determined by Minshew (1967) and is listed in Appendix 6.7.3.1 followed by chemical analyses in Appendix 6.7.3.2. The rocks of the Wyatt Formation in the La Gorce Mountains were altered either by the original magmatic fluid or during later metamorphism. In extreme cases, plagioclase was completely altered to sericite or saussurite (Stump et al. 1986). Saussurite is a mineral aggregate composed of albite and zoisite or epidote with variable amounts of calcite, sericite, and prehnite (Jackson 1997). 

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Fig. 6.12 The Scott Glacier flows north from the polar plateau and discharges ice into the Ross Ice Shelf. The Bartlett and Albanus glaciers are its principal tributaries. The major mountain ranges adjacent to the Scott Glacier are the La Gorce Mountains at its head and the Tapley Range east of its mouth. In addition, the map identifies Mt. Weaver, Mt. Wyatt, Mt. Gardiner, and Mt. Blackburn. The valley of the Leverett Glacier is located east of the Scott Glacier and drains the Harold Byrd Mountains to be discussed in Section 6.5 (Adapted from Mirsky 1969)...

Table 6.4 Stratigraphy of the basement complex of the La Gorce Mountains and the Leverett-Glader area of the Queen Maud Mountains (Stump et al. 1986 Stump 1995 Davis and Blankenship 2005)...

The Ackerman Formation of the La Gorce Mountains (Table 6.4) consists of a sequence of inter-bedded sedimentary and volcaniclastic rocks that crop out on the northern part of Ackerman Ridge in Fig. 6.13. Green shale at the base of the Ackerman Formation was deposited conformably on massive rocks of the Wyatt Formation. The top of the Ackerman Formation is faulted against the sedimentary rocks of the La Gorce Formation. The volcanic rocks of the Ackerman Formation resemble the Wyatt Formation in color, texture, phenocrysts content, and bulk chemical composition. The rocks were sericitized and mafic minerals were converted to chlorite, but the extent of... 

Fig. 6.14 Silica-variation diagrams of the silicic porphyries of the Wyatt Formation and of the Ackerman Formation in the La Gorce Mountains and in the upper Scott Glacier area (Data by Stump et al. 1986 Minshew 1967)...

Table 6.5 Age determinations of rocks in the La Gorce Mountains and other parts of the Scott Glacier area (Data from Mirsky 1969 Stump et al. 1986 Van Schmus et al. 1997 Faure unpub. [Appendix 6.7.3.3])...

Shand SJ (1947) Emptive rocks. Wiley, New York Smit JH, Stump E (1986) Sedimentology of the La Gorce Formation, La Gorce Mountains, Antarctica. J Sed Pet 56(5) 663-668... 

Fig. 6.6 The northwestern margin of the Nilsen Plateau at 86°20 S and 158°00 W of the Queen Maud Mountains is dissected by cirques and alpine vaUey glaciers that drain ice which has accumulated on the top of the plateau. Rock outcrops in the cirques and valleys of the northern Nilsen Plateau expose metasedimentary rocks of the La Gorce Formation and metavolcamc rocks of the...

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