Vestfold Mountains
| Vestfold Mountains | ||
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| Highest peak | Boulder Hill ( 157 m ) | |
| location | Princess Elisabeth Land , East Antarctica | |
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| Coordinates | 68 ° 33 ′ S , 78 ° 15 ′ E | |
| rock | Gneiss | |
| surface | 512 km² | |
 Satellite image of the Vestfold Mountains |
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The Vestfold Mountains are an Antarctic oasis with an area of rocky coastal hills on the Ingrid Christensen coast of the East Antarctic Princess Elisabeth Land . They are on the north side of the Sørsdal glacier .
geography
The hills are divided by three peninsulas that run to the west and bordered by narrow fjords. Most of the hills are between 30 and 90 meters high, the highest peak towers almost 160 meters. The size of the area is about 400 km². They are one of the few ice-free mainland regions in Antarctica.
Discovery story
They were discovered on February 20, 1935 by Captain Klarius Mikkelsen (* 1887) with the Norwegian whaler Torshavn . In the northern part, crew members carried out initial explorations.
The Vestfoldberge are to Vestfold named, a Norwegian Fylke (region) in which with Sandefjord is also the center of whale industry. The hilly area and the islands off the coast were mapped from aerial photos taken during the Lars Christensen expedition in 1936/37 . Later short landings were 1939 Lincoln Ellsworth and Hubert Wilkins made in the course of Operation Highjump 1946/47 further air photos were taken. In 1954 and 1955, ANARE (Australian National Antarctic Research Expeditions) carried out further landings and consecutive research. In January 1957, this expedition set up the Davis Station .
geology
The Vestfold Mountains are the exposed outcrops of the cratonized Vestfold Bloc. Its geodynamic evolution can be traced back to the Neo-Archean . Cratonization began with Felsic igneous activities, followed by intense tectono-thermal events. A significant crust elevation took place post-tectonically.
The Vestfold Block consists of three main rock complexes, which consist predominantly of Felsic igneous rocks. They are the Mossel gneiss complex, Crooked Lake gneiss complex and the Grace Lake granodiorite complex. A fourth complex of rocks is formed by the Chelnok supracrustal sequence .
The oldest rocks are the predominantly mafic granulitic Tryne-Meta volcanites . They come in different sizes in the form of rounded ellipsoidal (see also → Boudinage ) xenolites or tectonically caused deposits in the Mossel gneiss complex and Crooked Lake gneiss complex. The protoliths (parent rocks) were dated to at least 2,800 mya using zirconium cores and xenolite crystals together with the samarium-neodymium method (Sm-Nd method) .
The Chelnok supracrustal sequence was widely deposited in southern areas of the Vestfold Block. It forms a tectonic unit of varying thickness in which the Mossel gneiss complex and the Crooked Lake gneiss complex are embedded. It mainly consists of pelitic migmatites of different compositions with parts of biotite and garnet- containing gneisses. This sequence shows an age similar to that of the Tryne metavulcanites.
The Mossel gneiss complex consists mainly of tonalitic orthogneiss with minor proportions of granodiorites and granites . He formed widespread stratified areas. Its magmatic protoliths show a significant age distribution from 2,526 to 2,501 mya. They arose from partial melting of the Tryne metavolcanites.
The protoliths of the Crooked Lake gneiss complex have crystallization ages between 2,501 and 2,484 mya. It consists mainly of tonalitic, dioritic to Monzonitic rocks. The magmatites intruded all previous deposits and formed the largest unit of rock.
The protoliths of the Grace Lake granodiorite complex have an average age of 2,487 mya.
The first major deformation produced granulite facies between 2,501 and 2,487 mya , which was followed by the second phase at 2,487 mya, also with the formation of granulite facies.
Between 2,477 and 1,100 mya, mostly tholeiitic dyke or swarms of dykes intruded the rock packages. Most of them have not been deformed and have a predominantly north-south orientation.
Around 500 mya, hornblende - biotite-containing granites took place locally in the coastal area. Alkaline dykes and lamprophyres also intruded .
The geodynamic development as well as the crustal structure of the Vestfold Block differs from the adjacent region of the Rauer Islands , which suggests that they were not side by side in archaic times. Also nearby archaic terranos do not seem to have a comparable chronostratigraphy with the Vestfold block. However, the Napier Complex further south-west in Enderbyland and the Ruker Province of the southern Prince Charles Mountains in Mac Robertson Land contain rocks of similar age.
The Vestfold Block was originally tectonically connected to the East Indian Singhbhum Kraton, which is separated from the Eastern Ghats by the Mahanadi Trench .
Individual evidence
- ↑ Philips S. Target: Katabatic winds, hydraulic jumps and wind flow over the Vestfold Hills, East Antarctica . In: Antarctic Science . tape 10 , no. 4 , 1998, pp. 502–506 ( PDF file; 439 kB [accessed October 14, 2013]).
- ↑ W. Sheraton and KD Collerson: Archaean and Proterozoic geoloical Relationships in the Vestfold Hills Prydz Bay Area, Antarctica. In: BMR Journal of Australian Geology & Geophysics, 8, 119-128. Online article
- ↑ LP Black, PD Kinny, JW Sheraton and CP Delor: Rapid production and evolution of late Archaean felsic crust in the Vestfold block of East Antarctica. In: Precambrian Research, Volume 50, Issues 3-4, May 1991, Pages 283-310. doi: 10.1016 / 0301-9268 (91) 90026-7 , alternative
- ↑ Simon L. Harley, Ian CW Fitzsimons and Yue Zhao: Antarctica and supercontinent evolution: historical perspectives, recent advances and unresolved issues. In: Geological Society, London, Special Publications, 383, 1-34, 9 October 2013. doi: 10.1144 / SP383.9 , alterantiv
Web links
- SL Harley: The geology of Antarctica. In: Geology, Vol. IV, The Geology of Antarctica. PDF
- PD Kinny, LP Black and JW Sheraton: Zircon ages and the distribution of Archaean and Proterozoic rocks in the Rauer Islands. In: Antarctic Science, Volume 5, Issue 2 June 1993, pp. 193-206. doi: 10.1017 / S0954102093000252P , online article