The range is at the northwestern edge of the East Antarctic Craton.
To the west of the Shackleton Range, the Transantarctic Mountains run from north to south.
These mountains formed around 500 million years ago during the Pan-African Ross Orogony along the former Pacific edge of the East Antarctic Craton.
The two ranges differ in structural trends, being almost at right angles to each, and in rock types.
It is commonly thought that the Shackleton Range was caused by an oblique collision between the East Antarctic and Kalaharicratons that closed the Mozambique Ocean.[2]
The southern belt, exposed in the Read Mountains, has medium- to high-grade metamorphic rocks classified as the Read Group. They are mainly composed of partly migmatised quartzitic, basic, calcareous and pelitic rocks. In places they are interlayered with gneissic granites, and intruded by granites and basic rocks.
Dating of the metagranites gives ages of around 1,760 and 1,600 million years.
Rb–Sr and K-Ar mineral cooling ages are 1650–1550 million years.[2]
The Southern Terrane has detritus up to 2,850 million years old that experienced magmatism from 1,850 to 1,810 million years ago, a metamorphic event between 1,710 and 1,680 years ago, and another metamorphic event 510 million years ago.
Tectonics in the Southern Terrane during the Paleoproterozoic was very similar to that of the Mawson Continent, which may mean that this continent extends over the Eastern Antarctic Shield and includes the Shackleton Range.[4]
Eastern Terrane
The Eastern Terrane holds granitoid rocks formed around 1,060 million years ago during the Grenville orogeny that experienced metamorphism around 600 million years ago.
The events at 1,060 and 600 million years ago are similar to the Grenvillian and Pan-African tectonics in Queen Maud Land, suggesting that the Shackleton Range holds part of the Pan African Mozambique/Maud Belt.
The suture located in the extreme east of the range was formed during the amalgamation of West Gondwana and the Indo-Antarctic plate.[4]
Northern Terrane
The northern belt extends from the Pioneer Escarpment in the east to the northern Haskard Highlands in the west.
It has been divided into the Pioneers Group, the Stratton Group, and an ophiolite complex that may be a relic of the Mozambique Ocean.[2]
The Northern Terrane has paragneisses, mafic and ultramafic rocks that host granites and diorites dating to 530 million years ago, which experienced metamorphism 510 to 500 million years ago.
This terrane holds the suture formed when the combined Indo-Antarctic/West Gondwanan block collided with East Gondwana about 510 million years ago.
The suture may also extend through the Sør Rondane Mountains and the Lützow-Holm Bay area to the north.[4]
Topology
View from NASA's DC-8 flight over the continent on 21 October 2011
The Shackleton Range is 170 kilometres (110 mi) long in an east-west direction and up to 70 kilometres (43 mi) wide.[5]
It stretches from the Filchner Ice Shelf eastward until it is fully covered at a height of about 2,000 metres (6,600 ft) by the Antarctic ice sheet.
The range is an ice-covered plateau between 1,200 and 1,600 metres (3,900 and 5,200 ft) high that rises between two large glaciers.[6]
The plateau generally slopes down to the north, so most of the ice from the range flows via wide glaciers into the fast-moving Slessor Glacier, and much less flows south into the slower-moving Recovery Glacier. This probably explains why erosion is higher in the north of the range.[7]
The Shackleton Range is a rectangular horst rising above major fault zones now under the Slessor and Recovery glaciers.[8]
The center of the range is covered by a long ice cap extending from the Fuchs Dome in the west to Shotton Snowfield in the east, and bounded by cliffs as high as 400 metres (1,300 ft).
There are areas of rocky outcrop around the margins of the plateau.[6]
The Read Mountains on the southeast edge of the range are the highest, at 1,800 to 1,950 metres (5,910 to 6,400 ft), while there are lower peaks at 700 to 900 metres (2,300 to 3,000 ft) along the northern edge.[5]
The connected valleys of the north-flowing Gordon Glacier and south-flowing Cornwall Glacier may reflect an underlying fault zone, and have been treated as a divide between the western and eastern portions of the Shackleton Range.[9]
Read Mountains
The plateau surface is a discontinuous and faulted undulating peneplain, most visible on the south of the range.[8]
The flat areas free of ice at the edge of the Fuchs Dome and Shotton Snowfield and the table mountains that surround them are the remnants of the peneplain.[10]
In the Read Mountains there are south-facing cirques as wide as 7 kilometres (4.3 mi) surrounded by high cliffs.
The ridges between the cirques stretch over 10 kilometres (6.2 mi) to the south, and in seven cases widen to form flat-topped buttes.[5]
In the north and northwest the range is made up of small table mountains and isolated peaks.[5]
There are fifteen table mountains in the south of the range, seven in the southwest and just three in the north.[10]
Glacial activity
The geology and origin of glacial erratics, and the evidence of subglacial erosion in the Shackleton Range show that the whole range was once overrun by ice from the south or southeast.
The erratics were probably carried north from the Whichaway Nunataks and the Pensacola Mountains around the end of the Miocene during the last major expansion of the Antarctic ice sheet.[5]
The ice was 1,000 metres (3,300 ft) thicker than today, and the ice flowed north unaffected by the local landforms.[11]
During the Last Glacial Period, the Filchner ice shelf expanded and blocked the Slessor Glacier, which deposited till and scattered erratics.[5]
Today, the ice in most of the range still flows north into the Slessor Glacier.
However, ice from a small area in the southwest of the snowfield flows south between the Read Mountains and the Stephenson Bastion into the Recovery Glacier, and small glaciers carry ice south from the Read Mountains and Stephenson Bastion.[7]
The high table mountains in the south, exposed to the prevailing winds, have been free of ice for longest and have experienced more weathering than the lower mountains to the north.[10]
The Read Mountains have probably been ice-free since before the Quaternary.[11]
With few exceptions the table top mountains are free of glacial deposits, although glacial striations and crescentic gouges show that they have been subject to glacial activity in the past.
The assumption is that during the long ice-free period the deposits have been eroded away.[12]
80°35′S23°15′W / 80.583°S 23.250°W / -80.583; -23.250.
A large snowfield between Herbert Mountains and Pioneers Escarpment on the north and Read Mountains on the south, in the Shackleton Range.
The U.S. Navy obtained aerial photographs of the feature in 1967 and it was surveyed by BAS, 1968-71.
Named by the UK-APC, 1971, in association with the names of glacial geologists grouped in this area, after Frederick W. Shotton (1906-90), British Quaternary geologist and Professor of Geology, University of Birmingham, 1949-74. Not: Shottonfonna.[15]
The range lies between the Slessor Glacier to the north and the Recovery Glacier to the south, both of which flow west into the Filchner–Ronne Ice Shelf.[13]
Slessor Glacier is about 50 kilometres (31 mi) wide and drops from an elevation of over 800 metres (2,600 ft) at the eastern end of the range to about 200 metres (660 ft) at the western end where it enters the Filchner ice shelf.
This results in rapid flow, with areas of chaotic ice and many crevasses.
The Recovery Glacier is about 80 kilometres (50 mi) wide, and drops from about 1,200 to 800 metres (3,900 to 2,600 ft) along the range.
With a lower gradient it flows more slowly and has fewer crevasses.[5]
The Schimper Glacier, Gordon Glacier, Stratton Glacier and Blaiklock Glacier flow northwest from the range into the Slessor Glacier.
The Glen Glacier and Cornwall Glacier flow south into the Recovery Glacier.[13]
81°10′S28°00′W / 81.167°S 28.000°W / -81.167; -28.000.
Glacier, at least 60 miles (97 km) long and 40 miles (64 km) wide at its mouth, flowing west along the south side of the Shackleton Range.
First seen from the air and examined from the ground by the CTAF in 1957, and so named because of the recovery of the expedition's vehicles which repeatedly broke into bridged crevasses on this glacier during the early stages of the crossing of Antarctica. Not: Glaciar Expedicion Polar Argentina, Glaciar Falucho.[23]
79°50′S28°30′W / 79.833°S 28.500°W / -79.833; -28.500.
Glacier at least 75 miles (121 km) long and 50 miles (80 km) wide, flowing west into the Filchner Ice Shelf to the north of the Shackleton Range.
First seen from the air and mapped by the CTAE in 1956.
Named by the CTAE for Marshal of the RAF Sir John Slessor, chairman of the expedition committee.[24]
Glacier (80°44′S25°16′W / 80.733°S 25.267°W / -80.733; -25.267) at least 7 miles (11 km) long, flowing south in the Shackleton Range to join Recovery Glacier to the west of Read Mountains. First mapped in 1957 by the CTAE and named for Alexander R. Glen, member of the Committee of Management of the CTAE, 1955–58.[25]
80°18′S25°05′W / 80.300°S 25.083°W / -80.300; -25.083.
A glacier in the east part of Herbert Mountains, Shackleton Range, flowing north-northeast into Slessor Glacier.
Photographed from the air by the U.S. Navy, 1967, and surveyed by BAS, 1968-71.
In association with the names of glacial geologists grouped in the area, named by the UK-APC after Karl Friedrich Schimper (1803–67), German botanist who in 1835 originated the theory of
the Ice Age in Europe to account for the distribution of erratic boulders.[27]
80°30′S29°51′W / 80.500°S 29.850°W / -80.500; -29.850.
Glacier 16 miles (26 km) long, flowing north from Turnpike Bluff, then northwest to Mounts Provender and Lowe in the west part of the Shackleton Range.
First mapped in 1957 by the CTAE and named for Kenneth V. Blaiklock, leader of the advance party of the CTAE in 1955-56 and surveyor with the transpolar party in 1956-58.[30]
80°38′S26°30′W / 80.633°S 26.500°W / -80.633; -26.500.
Pass between Gordon and Cornwall Glaciers in the central part of the Shackleton Range.
First mapped in 1957 by the CTAE and so named because this pass, together with Gordon and Cornwall Glaciers, provides a sledging route across the Shackleton Range from north to south.[31]
80°28′S28°20′W / 80.467°S 28.333°W / -80.467; -28.333.
A snow pass at c. 1,000 metres (3,300 ft) trending east-west between the northwest side of Fuchs Dome and Flat Top in the Shackleton Range.
The area was surveyed by CTAE in 1957.
Named by the UK-APC after Michael A. Warden, BAS general assistant, Halley Station, 1970-72, who worked in the area.[32]
Laird, M.G. (1991), Thomson, M.R.A.; Crame, J.A.; Thomson, J.W. (eds.), Lower-mid-Palaeozoic sedimentation and tectonic patterns on the palaeo-Pacific margin of Antarctica, in Geological Evolution of Antarctica, Cambridge: Cambridge University Press, pp. 178–179, ISBN9780521372664
Will, Thomas; Zeh, A.; Gerdes, Axel; Frimmel, Hartwig; Millar, I.L.; Schmädicke, E. (2009), "Palaeoproterozoic to Palaeozoic magmatic and metamorphic events in the Shackleton Range, East Antarctica: Constraints from zircon and monazite dating, and implications for the amalgamation of Gondwana", Precambrian Research, doi:10.1016/j.precamres.2009.03.008
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