Dufek Intrusion

The radar-echo surveys of the Antarctic ice sheet by Drewry (1975) provided information about the sub-ice topography but did not detect mineral deposits. More recently, Behrendt et al. (1980) combined the radar-echo sounding technique of Drewry (1975) with an airborne magnetometer survey which revealed that a laige part of the Dufek intrusion in the Pensacola Mountains is covered by the East Antarctic ice sheet. The enlargement of the area of this intrusion increased the amount of potential ore of iron, titanium, and vanadium in this differentiated body of gabbro, pyroxenite, and anorthosite. 

Ford, A.B. The Dufek intrusion of Antarctica and a survey of its minor metals and possible resources. In, J.C. Behrendt, ed. Petroleum and Minerals Resources of Antarctica. US Geol. Surv., Circular 909 51-75. Alexandria, VA... 

Ford, A.B., R.E. Mays, J. Haffty, and B.P. Fabbi. Reconnaissance of minor metal abundances and possible resources of the Dufek intrusion, Pensacola Mountains. In, R.L. Oliver, P.R. James, and J.B. Jago, eds. Antarctic Earth Science, 433 36. Australian Acad. Sci., Canberra, A.C.T... 

Behrendt JC, Drewry DJ, Jankowski E, Grim MS (1980) Aeromagnetic and radio-echo ice sounding measurements show much greater area of the Dufek intrusion, Antarctica. Science 209 1014-1017... 

The Kirkpatrick Basalt does not occur in the Queen Maud, Horlick, Thiel, and Pensacola mountains. Exposures of basalt in the Shackleton Range have not been correlated with the Kirkpatrick Basalt However, sills of Ferrar Dolerite do occur in the Whichaway Nunataks (Brewer 1989), in the Theron Mountains (Blundell and Stephenson 1959 Brewer et al. 1987, 1992). In addition, basalt magma pooled in a large magma chamber in the crust beneath the Pensacola Mountains where it differentiated into the layered gabbro complex of the Dufek intrusion (Ford and Kistler 1980). 

Burmester RF, Beck ME (1981) Paleomagnetism of the Dufek intrusion. Antarctic J US 16(5) 58-60 Burmester RF, Sheriff SD (1980) Paleomagnetism of the Dufek intrusion, Pensacola Mountains, Antarctica. Antarctic J US 15(5) 43-45... 

Ferrar Group Dolerite Sills and the Dufek Intrusion... 

The stratification of the Basement sill anticipates the much more extensive layering of the Dufek intrusion in the Pensacola Mountains to be presented in Section 13.4. The geology of the principal differentiated gab-bro intrusives of the Earth was described by Faure (2001) and by Cawthorn (1996). 

The Dufek intrusion is a layered deposit of mafic and ultramafic plutonic rocks that form the Dufek Massif and parts of Forrestal Range of the northern Pensacola Mountains (Schmidt and Ford 1969 Ford et al. 1977 ... 

Rankine Rock located about 30 km northeast along a northwest-facing escarpment. The Dufek intrusion is cut by normal faults, called the Enchanted Valley faults, which extend parallel to the Dufek Massif with the downthrown side on the north. In other words, the Dufek Massif is the mountain range that is composed of the Dufek intrusion. The Dufek Massif contains several jagged peaks including Walker, Neuberg, Aughenbaugh, and Hannah. Other noteworthy locations are Spear and Frost spurs, Davis Valley, and Rankin Rock. The total area occupied by the Dufek Massif is approximately 700 km (Ford and Boyd 1968). 

Ford and Boyd (1968) divided the Dufek intrusion into several descriptive series listed in Table 13.2. The intrusion is underlain by lightly folded sedimentary rocks of Paleozoic age which rest unconformably on the tightly folded low-grade metamorphic rocks of the Patuxent Formation (Section 8.2.3). The older sequence... 

Table 13.2 Stratigraphy of the Dufek intrusion in the Dufek Massif and the Forrestal Range (Ford and Boyd...

Table 13.3 Refined stratigraphy of the Dufek intrusion in the Forrestal Range and the Dufek massif (Ford 1976)" ...

Fig. 13.40 The Dufek intrusion in the northern Pensacola Mountains extends from the Dufek Massif across the Sallee Snowfield to the Forrestal Range. Geophysical surveys by Behrendt et al. (1974, 1979, 1980, 1981) indicate that the intrusion is a continuous tabular body that extends north about 250 km from the northern tip of the Dufek Massif. Ferris et al. (1998) questioned this extrapolation of the area of the Dufek intrusion and reduced it from about 50,000 to only 6,600 km. Even in that case, the area of the Dufek intrusion is exceeded only by the Bush veld Complex of South Africa (Adapted from Ford 1990)...

Fig. 13.41 The Dufek Massif is composed almost entirely of the stratified gabbroic cumulates of the Dufek intrusion which is genetically related to the Middle Jurassic Ferrar Dolerite. This mountain range consists of steep-sided peaks and ridges that... 

The Frost Pyroxenite Member occurs near the top of Neuberg Peak about 800 m above the base of the Aughenbaugh Gabbro (Figure 13.41). The northeasterly dip of the Dufek intrusion causes the Frost Pyroxenite to crop out in the Davis Valley at the... 

Fig. 13.42 The Dufek intrusion extends from the Dufek Massif under the SaUee Snowfield to the Forrestal Range located about 75 km to the southeast. The Forrestal Range consists primarily of the Saratoga Table and the Lexington Table both of which are...

The average chemical compositions of the various differentiated facies of the Dufek intrusion in Appendix 13.6.8 and Fig. 13.43 show the effects of fractional crys-... 

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