Seen The eastern Gjelsvikfjella ( Risemedet ) from northeast
The Gjelsvikfjella is a mountain range in Queen Maud Land, whose ice-free peaks and nunataks extending over an area of 48 kilometers in north-south direction and about 40 km in east-west direction. The distance to the ice edge is about 200 kilometers. Was named the mountain range after the Norwegian geologist and resistance fighters gates Gjelsvik, the longtime director of the Norsk Polarinstitutt.
The mountain range consists of four mountain ranges, which are separated from each other by several kilometers wide glacier.
To the north is the Mayr chain (Norwegian Jutulsessen ). The southwest and make up Nupskammen From Essenskarvet that s have on the map about the shape of an upside down " T". In the south of the Sauter bolt (Norwegian Terningskarvet ) and to the east is finally the Risemedet.
The highest peak of Gjelsvikfjella is the highest peak of the massif Risemedet with 2704 m. In the north, the mountain range dissolves into a number of nunataks with altitudes 1100-1400 m, in the south also extend individual peaks, which are separated from one another by ice, from the glaciated polar plateau out. To the west and east of the mountain range is limited by wide glacier. The Sveabreen in the west separates the Gjelsvikfjella of the HU Sverdrupjella, in the east of Tønnesenbreen forms the border with the Mühlig -Hofmann Mountains. Both glaciers unite on the northern foothills of the mountains and flow out to the Fimbulisen.
The mountain consists of highly metamorphosed, multiply folded gneisses and amphibolites, whose output rocks volcanic and granites are of an island arc with mesoproterozoischem age. At the turn of the Neoproterozoic Mesoproterozoikum these rocks were the Kaapvaal craton first overprinted deformed and metamorphosed during the collision of the island arc, with the temperature exceeding the melting point of granite and there was local to the formation of migmatites. From the deep crust and upper mantle melts penetrated with a granitic composition and tonalitischer which solidified in the form of thin transitions.
Another deformation went through the rocks in the collision of West and East Gondwana around 540 mya, with the current Faltenbau arose. Since the Ordovician is subject to the mountain of the ablation. In some places you will find Upper Jurassic basalt transitions, demonstrating that the breakup of Gondwana in this region large amounts of lava were promoted.
Because until 2005 there was no consistently occupied station in the Gjelsvikfjella, there are no long-term climatic observations. The extent of previous observations known, the temperatures are below freezing all year. The highest temperatures are reached in January with -2 ° C. In mid-January can be between -4.5 ° C and 19 ° C and allow at an average temperature of 2.5 ° C lower plants growth at protected sites, the soil temperature.
Fauna and Flora
The fauna of the Gjelsvikfjella includes a kind of springtails and three types of mites, as well as three species of birds that have their summer breeding grounds in the mountains. Most animals were registered in the Mayr chain, there exist three open valleys to the north with extended, stable debris and Moränenbedeckung, in which the birds find suitable nesting sites. In the vicinity of these hatcheries are also small organisms that feed on bird excrement and food remnants, a suitable habitat. The two most common birds are the snow petrel ( Pagodroma nivea ) and the Antarctic petrel ( Thalassoica antarctica) with a total of about 25,000 pairs, as well as the predatory Südpolarskua ( Catharacta maccormicki ).
Mites are represented by the types Eupodes angardi and Tydeus erebus, which are common in many mountain regions of Dronning Maud land. The type of mite Maudheimia marshalli COETZEE until 1997 newly described previously could only be detected in the Gjelsvikfjella and the immediately neighboring western and eastern mountain ranges.
Springtails are represented by the type Cryptopygus sverdrupi that occurs mainly in small moss or algae colonies in central Dronning Maud Land.
The vegetation in the Gjelsvikfjella is limited to mostly north exposed, stable scree slopes and rock surfaces, the deposits are often in the vicinity of breeding sites. There the green alga Prasiola crispa occurs in small mats of several decimeters in diameter. Other genera in less nitrate- rich environment are Nostoc, Ulothrix and Leproloma.
On two specially protected sites on the chain of Mayr north upstream nunataks come the Moose Grimmia lawiana and Sacroneurum before glaciale.
Common lichens as Rhizocarpon geographicum, Xanthoria elegans and Candelariella hattensis colonize the slightly more weathered parts of the silicate rocks and were detected up to an altitude of 2550 meters. In addition, there are approximately a dozen other lichen species known, of which Xanthoria candelaria and Physcia caesia are limited to the vicinity of breeding sites.
Discovery and Exploration
On January 29, 1939, the mountain range was discovered at the German Antarctic Expedition flights 1938/39, and documented with aerial photographs. Since most aerial photographs during the Second World War were lost, the mountain was again taken up by photogrammetry during the Norwegian Antarctic Expedition 1956-1960 and calibrated also control points on the ground for a more precise orientation. On the from 1966 published by the Norsk Polarinstitutt topographic maps at a scale of 1:250,000, the area between 2 ° and 3 ° 30 'East was recognized as an independent mountain group called Gjelsvikfjella. On the German general map, which was settled Alfred Ritschers Expeditionary Ribbon, the area was the westernmost part of the Mühlig -Hofmann Mountains. The Russian maps of the 1960s showing the area as part of the Mühlig -Hofmann Mountains, but the Norwegian mountain classification and nomenclature has since prevailed.
The first geological research took place within the framework of the 4th Soviet Antarctic Expedition 1958-1960. The systematic mapping and exploration from 1989-1990 was continued by Norwegian expeditions, which refer to the 1989 open station Troll used. In the austral summer 1999/2000 a German expedition visited the area and carried out geological work.