چکیده:
In northern Kazakhstan and neighbouring parts of the West Siberian Plain of Russia is one of the world’s biggest concentrations of pans. The area has thousands of them. Landsat imagery and Google Earth images indicate their distribution within this semi-arid area and their forms and associated lunette dunes. Many of the pans, most of which are small, wet and shallow, show a characteristic shape and orientation and some have developed in Pleistocene dune fields. Others have developed in old river channels and from the deflation of lake floors. The pans are in a low-relief area developed on Palaeogene, Neogene and Quaternary beds and have been shaped by winds coming from the south west. They occur in an area which is predominantly steppe grassland. Comparisons can be made with other global pan areas in terms of their number, densities, areas, and depths and in terms of the materials on which they have developed, and the climatic conditions that occur here they are found. Highlights One of the world’s biggest, previously unstudied, areas of aeolian pans Data are presented on the main pan morphologies and their morphometry The pans have morphological similarities to those observed in areas like the High Plains of the USA, South Africa, the Pampas of Argentina and Australia
خلاصه ماشینی:
"Landsat imagery and Google Earth images indicate their distribution within this semi-arid area and their forms and associated lunette dunes.
Highlights· One of the world’s biggest, previously unstudied, areas of aeolian pans· Data are presented on the main pan morphologies and their morphometry· The pans have morphological similarities to those observed in areas like the High Plains of the USA, SouthAfrica, the Pampas of Argentina and Australia Keywords: Pans; Wind erosion; Kazakhstan steppes; West Siberian Plain 1.
Locations of some major classic panfields (View the image of this page) Zimbabwe 18 49S 26 21E Regional descriptions of lunettes are provided for the High Plains of the USA by Holliday (1997), Tunisia by Perthuisot and Jauzein (1975), the Kalahari in Botswana by Lancaster (1978), South Africa by Goudie and Thomas, (1986), Mauritania by Mohamedou et al.
These forms appear to be broadly comparable to the palaeo-channel pans of Western Australia (Bourne and Twidale, 2010) or of the High Plains of the USA (Goudie and Wells, 1995).
Although most of the pans occur in herb and grass dominated areas (steppe), as is also the case for the Argentinian Pampas, the High Plains of the USA, and the veld of South Africa, some occur in areas of pine forest and bogs, which also suggests they may be out of equilibrium with the present climate.
Westerly winds are also the formative ones in other mid-latitude pan areas, including the High Plains of the USA the Pampas of Argentina, and the Lake Chrissie Pans of South Africa (Wellington, 1943)."