8. Beacon Supergroup

The geology of the Ohio Range as it is presently understood is presented in this book in Section 7.5.1 (basement rocks) and in Section 10.5.2 (Beacon Supergroup). In addition. Fig. 10.22 depicts the adit of the Dirty Diamond Coal Co. from which Bill... 

McMurdo Volcanic Group Ferrar and Kirkpatrick groups Beacon Supergroup Kukri Unconformity... 

Beacon Supergroup Admiralty Intmsives in the Robertson Bay and Bowers terranes Gallipoli Porphyries... 

Fig. 4.2 Northern Victoria Land consists of three terranes that are separated from each other by the Leap Year and Lanterman faults. Each terrane is composed of characteristic assemblages of metasedimentary and metavolcanic rocks of Neoproterozoic and Cambrian ages. These basement rocks were locally intruded by plutons of the Granite Harbor Intrusives and by the younger Admiralty Intrusives. Rocks of the Beacon Supergroup occur only in a few places in northern Victoria Land including in the Morozumi Range and HeUiwell HiUs, in the adjacent Freyberg Mountains, and in the Lichen HiUs. The Kukri Peneplain, which is so prominent in southern Victoria Land, is only preserved in these locations (Adapted from Stump 1995)...

Fig. 4.6 The basement rocks of southern Victoria Land extend northward across the David Glacier into the Terra-Nova-Bay region of the Wilson Terrane of northern Victoria Land (NVL). The basement rocks of this region consist mainly of Granite Harbor Intrusives and of metasedimentary rocks of Neoproterozoic to Cambrian age. The rocks above the Kukri Peneplain are not shown (i.e., Beacon Supergroup, Ferrar Dolerite, and McMurdo Volcanics). This area contains several prominent mountains including Mt. Melbourne which is an extinct volcano of the Cenozoic McMurdo Volcanics (Adapted from Warren 1969 Gair et al. 1969 Skinner 1983)...

The Salamander Range is located southeast of the Lanterman Range and is separated from the Freyberg Mountains by the upper Canham Glacier. The northern part of the Salamander Range consists of Wilson Gneisses which, in the southernmost part, is overlain by residual outcrops of the Beacon Supergroup and of the Kirkpatrick Basalt. 

Fig. 4.19 The Bowers Terrane occupies the central area of northern Victoria Land flanked by the Wilson Terrane in the west and the Robertson Bay Terrane in the east The major rock types of this segment of the Transantarctic Mountains are identified by capital letters in alphabetical order A = Admiralty Intmsives, B = Beacon Supergroup, BT = Bowers Terrane, G = Granite Harbor Intrusives, P = Galhpoli Porphyries, R = Robertson Bay Group, W = Wilson Group. The Kirkpatrick Basalt has been onritted from this map for the sake of clarity and the Ferrar Dolerite sills are included with the Beacon Supergroup. The Lanterman and Salamander ranges constitute the eastern province of the Wilson Terrane (Adapted from Gair et al. 1969)...

The rocks of the Bowers Supergroup are locally overlain by erosional remnants of the Beacon Supergroup (Permian to Triassic) which includes sills of the Ferrar Dolerite (Middle Jurassic). In addition, erosional remnants of the Kirkpatrick Basalt plateau (Middle Jurassic) are present adjacent to the Lanterman Range and in the Leitch Massif (Gair et al. 1969). 

The basement rocks of the central Transantarctic Mountains are exposed primarily along the coast, except for the Geologist and the Miller Ranges which are located at the edge of the polar plateau more than 80 km inland of the coast The basement rocks along the coast are unconfonnably overlain by the sedimentary rocks of the Beacon Supergroup which were intruded... 

Fig. 5.1 The central Transantarctic Mountains include the area between the Nimrod and Beardmore Glaciers. The Byrd Glacier in the north and the Shackleton Glacier in the south are off this map. The basement rocks of this area crop out along the coast and are overlain by sandstones of the Beacon Supergroup farther inland. The only exceptions are the Miller and Geologist Ranges at the head of the Nimrod Glacier (Fig. 5.2) where the Nimrod Group is exposed (Adapted from Gunner 1976...

Fig. 6.5 The western edge of the southern part of the Nilsen Plateau along the Amundsen Glacier contains small outcrops of metavolcanic and metasedimentary rocks of the basement complex that were intruded by the Granite Harbor suite. McLelland (1967) divided the granitic basement rocks into the Cougar Canyon Quartz Monzonite, the Lonely Ridge Granodiorite, the North Quartz Monzonite, and the South Quartz Monzonite which are not differentiated on this map. The basement rocks are unconformably overlain by sandstones of the Beacon Supergroup and sdUs of Ferrar Dolerite (Adapted from McLelland 1967)...

The valley of the Blackwall Glacier in Fig. 6.7 also contains several small outcrops of cross-bedded quartzite and shale which were described by Stump (1985). The relation of these rocks to the La Gorce and Wyatt formations is uncertain. All of the basanent rocks of the Nilsen Plateau are unconformably overlain by the sedimentary rocks of the Beacon Supergroup (Devonian to Triassic) described by Long (1965). The Beacon rocks were intruded by sills of Ferrar Dolerite which are not shown in Fig. 6.5 and 6.7. 

Fig. 6.7 The basement complex of the northern part of the Nilsen Plateau consists of the La Gorce and Wyatt formations and of the Granite Harbor Intrusives. The volcano-sedimentary rocks predominate in the northern part of the Nilsen Plateau, whereas Granite Harbor Intrusives dominate the basement rocks of the southern part in Fig. 6.5. The Blackwall Glacier was referred to as the Black Rock Glacier by McLelland (1967). The Kukri Peneplain that divides the basement from the overlying Beacon Supergroup is not flat in this area but has elevation differences of about 34 m (Adapted from Stump 1985, 1995)...

LaGorce and Wyatt formations and with the Granite Harbor Intrusives. Sills and dikes of the Ferrar Dolerite are rare in the Wisconsin Range, in contrast to the Transantarctic Mountains between southern Victoria Land and the Amundsen Glacier where numerous dolerite sills occur within the Beacon Supergroup. 

I I Beacon Supergroup H Granite Harbor Intrusives I I Cambrian Pyroclastics B Wyatt Formation H La Gorce Formation... 

Beacon Supergroup have been preserved along the Olentangy Glacier in Fig. 7.4 and at the eastern end of the Wisconsin Plateau near Mt. Brecher (2,098 m) and Mt. LeSchack (2,265 tn). 

Fig. 7. 22 The basement rocks of the Ohio range consist of gra- of the Beacon Supergroup. Mt. Schopf is capped by a siU of the...

The rocks exposed in the Thiel Mountains belong to the basement complex of the Transantarctic Mountains. The sedimentary rocks of the Beacon Supergroup that uncon-formably overlie the basement rocks elsewhere in the Transantarctic Mountains do not occur in the Thiel Mountains either because they have been removed by erosion or because they were not deposited there. The stratigraphy of the basement rocks of the Thiel Mountains in Table 8.1 is deceptively simple compared to the basement rocks elsewhere in the Transantarctic Mountains (e.g., the Queen Maud Mountains and the Wisconsin Range). 

Fig. 8.8 The basement rocks of the Neptune Range in the Pensacola Mountains consist of the isoclinally folded metasedimentary rocks of the Hannah Ridge Formation (defined by Rowell et al. 2001) which is unconformably overlain by the Nelson Limestone (late Middle Cambrian) followed by the Gambacorta Rhyolite and the Wiens Formation (Cambro-Ordovician). These basement rocks were locally intruded by the Serpan Granite and by the hypabyssal Mount Hawkes Porphyry. The Paleozoic sedimentary rocks include the Gale Mudstone which is a trUite of Permian age which resembles the Buckeye Tillite of the Beacon Supergroup in the Ohio Range of the Horlick Mountains (Adapted from Schmidt and Ford 1969 with information from Stump 1995)...

A unique feature of the Pensacola Mountains is that Paleozoic formations of the Neptune and the Forrestal ranges were folded during the Weddell Orogeny of late Paleozoic age. This event distinguishes the Paleozoic formations of the Pensacola Mountains from the sedimentary rocks of the Beacon Supergroup elsewhere in the Transantarctic Mountains which have low dips of less than 10° and were folded only locally along faults. 

The only erosional remnant of the Beacon Supergroup is a small outcrop of Permian tillite and overlying siltstone in the eastern Shackleton Range. 

Barrett PJ, Elliot DE, Lindsay JE (1986) The Beacon Supergroup (Devonian-Triassic) and Eerrar Group (Jurassic) in the Beardmore Glacier area, Antarctica. In, MD Turner and JE Splettstoesser, eds. Geology of the Central Transantarctic Mountains. Antarctic Research Series, 36 339 28. Amer, Geophys. Union, Washington, DC... 

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