Heimefront Range

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The Heimefrontfjella is a 150 km long mountain range in East Antarctica, the 15 'extends from about 13 ° to 9 ° 15'W and 74 ° to 75 ° 15 'S, over an area of 3900 sq km in northeast-southwest direction. The Heimefrontfjella lies in the western part of the claimed of Norway Dronning Maud Land. Through the wide glacier Heimefrontfjella is divided into four parts ice-free mountain. These are from northeast to southwest, the Kottasberge ( norweg. Milorgfjella ), XU fjella, Sivorgfjella and Tottanfjella.

Geography

The Heimefrontfjella forms an indented fracture stage, which dams up the ice of the polar plateau over 2,200 m above sea level. The peaks of the mountains tower usually just above the polar plateau beyond; steep, ice-free rock walls are exposed mostly to the north and northwest. The highest mountain is the Paalnibba 2711 m. Three mighty glaciers share the Heimefrontfjella in four mountain parts that have their own name. Between the Kottasbergen and the XU - fjella the Haugebreen Glacier flows to the west. The XU - fjella is separated from the Sivorgfjella by the KK - Dalen. The glaciers meet at the foot of the mountains on the Aubertisen. Between the Sivorgfjella and Tottanfjella is the Kibergdalen. In front of the mountains to the northwest is the glaciated, up to 1350 m high Ritscherhochland.

Discovery and exploration of Heimefrontfjella

The Heimefrontfjella was spotted by the German Antarctic Expedition 1938/39, under the direction of Alfred Ritscher ( 1879-1963 ) during the first photogrammetric flight on 20 January 1939. The flight had to be canceled because of poor visibility, however, at an early stage, and on the overview map of the expedition only the outlines of the northern part of the Heimefrontfjella can be seen. The mountain was Kottas Mountains named after the captain of the expedition ship MS Swabia, Alfred G. Kottas. During the Norwegian - British - Swedish Expedition 1949-52, the mountains were flown twice. On the basis of the resulting oblique aerial images created the Norsk Polarinstitutt two topographic maps at a scale of 1:250,000 covering the northern and southern part of Norway renamed Heimefrontfjella Mountains.

In 1961 the Heimefrontfjella was first reached by land by a British expedition led by a geodetic and geological program. Also in the following years until 1966 were held British expeditions, the results were a geological overview map at a scale of 1:250,000 and some basic publications on the geology and biology of these regions.

Since 1985/86 the Heimefrontfjella was the target of German and Swedish expeditions. Swedish scientists led by glaciological research, German scientists have focused on the mountain geology and geophysics. The geological work continued until the austral summer 2000/ 01. As the first mountain in Antarctica, the Heimefrontfjella was completely in scale 1: 25,000 geologically mapped.

Designation of geographical objects

The Norwegian name Heimefrontfjella means " Home Guard Mountains" and is reminiscent of the Norwegian resistance during World War 2. For example, the KK - Dalen and the XU - fjella were designated according to the codes for operating in the Norwegian underground resistance groups. Other names are given in honor of the first British surveyors and geologists (eg Juckeskammen, Bowrakammen, Ardusberget ). Two objects were named by German expeditions Wallner tip and the Weigelnunatak in the northern Heimefrontfjella. Also the 1939 Kottasberge assigned name was used on the 2001 published satellite image map for the northern part of the mountains again.

Geology

Based on radiometric dating, one can distinguish the following geological units in the Heimefrontfjella:

• Last one in the late Mesoproterozoikum deformed bedrock;
• Parts of a Cambrian orogenic belt in which the older parts of the Mesoproterozoic orogen were impressed again deformed and metamorphosed;
• A locally preserved Permian overburden with plant fossils and thin coal seams;
• Basalt and basalt courses which have been dated to the Middle Jurassic.

Metamorphic basement

The mesoproterozoische bedrock is well exposed in the northern Kottasbergen Heimefrontfjella, so that the geological history can be reconstructed there. It is dominated by banded gneisses with a trondhjemitisch - tonalitisch - dioritic composition are associated with several generations of coarse-grained metamorphic granites. The rocks were formed in a late - Mesoproterozoic island arc ( Kottas Arc ) mya before 1200-1100. For the central and southern Heimefrontfjella an embossed by extension and magmatism backarc basin is adopted at the same time. The oceanic island arc was south of the Kaapvaal - Grunehogna craton. The Tugela Ocean was mya Before about 1080 concluded between the island arc and the Kaapvaal craton - Grunehogna and deformed the rocks of the island arc while sweeping and metamorphosed.

Only the eastern part of the Heimefrontfjella was affected in the Cambrian of an orogeny, in which the rocks were overprinted again deformed and metamorphosed. This mountain range was created as a result of the collision of East and West Gondwana, whereby one of the largest mountain belt of the earth's history, the East African Orogen - East Antarctic arose. The western boundary of the Cambrian Mountains is marked by a several -kilometer-wide shear zone.

Unterpermisches overburden

After the formation of Gondwana in the Cambrian the Heimefrontfjella has long ablation area. Towards the end of the Carboniferous there was a Verebnungsfläche with low relief on the differences in formation of a mighty ice sheet. Remains of this area occur in the northern Heimefrontfjella for days and show glacial scratches and bumps round. After the ice retreat sediments were deposited, the use of the base with Diamiktiten. About the Diamiktiten few meters follow finely stratified sand and siltstone with dropstones, also follow bright fine sands, are found in those well-preserved leaf imprints. This sequence represents the deposition of a delta in a periglacial lake dar. On Schivestolen, the highest peak of the Kottasberge are still about 140 m of yellowish sandstones with Kohleflözchen receive. The age of the overburden could be narrowed with palynological methods to the Lower Permian ( Asselian to Sakmarium ).

Fauna and Flora

The Heimefrontfjella has a typical for the continental Antarctic lichen vegetation with 18 species. It is dominated by lichens of the genera Lecidea, Acarospora, Lecanora and Xanthoria. In a few places also occurs the foliose lichen Umbilicaria. On north facing scree slopes the Moose Sarconeurum was glaciale and Grimmia sp. discovered that also occur in other ice-free regions of Antarctica. The only known terrestrial species are three types of microscopic mites and a species of springtails. In the Heimefrontfjella due to the relatively large at 300 km distance from the coast only breed a few pairs of snow petrel Pagodroma nivea and living by his balls and boys Skua Stercorarius maccormicki.

Research stations

Currently ( 2009) only operates a research station in Sweden Heimefrontfjella. The Svea station is located at 74 ° 35 'S and 11 ° 13'W at the output of Scharffenbergbotnen at 1245 m above sea level. Svea was built in the southern summer of 1987/88 and is only used as a summer station.