Large Meteorite Impacts (2003) 4117.pdf EFFECT OF THE SUPPOSED GIANT IMPACT CRATER ON THE GEOLOGIC EVOLUTION OF THE URAL MOUNTAIN RANGE. G. A. Burba, Laboratory of Comparative Planetology, Vernadsky Institute of Geochemistry and Analytical Chemistry, 19 Kosygin St., Moscow 119991, Russia e-mail: [email protected] Introduction: At the eastern outskirts of the Basement topography: There is an isometric de- European part of Russia there are the Ural Mountains, pression in the basement under the MURS. Its depth is which marks the border between Europe and Asia. down to –8 km. There are two uprises of the basement This mountain range have in general the straight linear with summits located at –3 km depth. These uprises position N to S along 60° E meridian. Such position are located just under the two uprises in the surface changes abruptly within the middle segment of the topography within the central area of the MURS. The range, between 54 and 59° N, where the mountain depth to diameter ratio for the depression of the base- chains curves eastward along the semicircular outline. ment is 1/50. Such change looks to be caused by some obstacle, the Paleoenvironment: Paleogeographical maps lithospheric heterogeneity. show the depression of the surface within the outlines This eastward-looking arc of the Middle Ural of the MURS beginning from Precambrian time. Mountains is considered here as an eastern segment of Mineral resources: The overwhelming majority a large ring structure, which is referred hereafter as of the mineral fields of the Ural Mountains are concen- Middle-Ural Ring Structure (MURS). The structure is tated within the MURS, to put it more precisely, within located between 54 and 59°, 52 and 62° E. The mini- the eastern half of its rim. There are ore fields of iron, mal diameter of its rim is 400 km. copper, chromite, nickel, tungstein, gold, and some Surface topography: The eastern half of the other metallic mineral resources here, as well as of the MURS rim is a part of the Ural Range from Yamantau well-known Ural gems. One could say, that the mining Mountain in the south to the area of Kachkanar Moun- industry of the Ural is in intimately connection with tain in the North. NW part of the rim is Okhanskaya MURS. So, MURS makes the industrial power of the Vozvyshennost (Highland) to the North of Kama river. Ural. Western part is Sarapulskaya Vozvyshennost. SW part Interpretation: The whole set of the data pro- is Bugulminsko-Belebeyevskaya Vozvyshennost (to vides a possibility to conclude that the MURS have a the South of Belaya river). There are two uplands in structure, which looks like a giant impact crater, simi- the central part of the MURS, both are N to S elon- lar to the craters on the other planets. This crater have gated: Tulvinskaya Vozvyshennost and Sylvinskiy a sharp expression in the basement topography, and Kryazh (Range). The SE part of the MURS bottom is not so sharp expression in the surface topography. occupied with Ufimskoye Plateau. Such smoothing view of the surface topography could The topographic level of the eastern segment of be connected with a thick layer of sediments, which MURS rim is up to 1000-1500 m above sea level, NW have filled the crater. Uprises in the central part of the segment – up to 300 m, W segment – up to 200-250 m, MURS could be considered as places of the crater’s SW – up to 300-350 m. The uplands in the central part central mountains, as they are located over the base- of MURS are up to 400-450 m. Minimal altitude ment uprises. The mineral fields looks to be in con- within the MURS is 58 m (in Kama river valley, near nection with the activity within the presumable ring Belaya river mouth), and maximal is 1640 m (Yaman- faults of the structure’s rim. tau Mountain on the south rim of MURS). Conclusion: It could be suggested that the geo- River net patterning: The ring of MURS is out- logic evolution of the Middle Ural area took place lined inside with a general pattern of the large river within the net of faults, which have been originated valleys of Chusovaya, Belaya, and Kama river (the during the impact event in Precambrian time and stay segment between the mouths of Chusivaya and Belaya, active during the further periods of geologic history. It the left tributaries of Kama). Valleys of a smaller (in- looks like that MURS have been a stable obstacle dur- termediate-sized) river valleys also outline a MURS ing the formation of the Ural Mountains, so the ranges concentric patterning. The directions of small-sized could not overpass through the MURS and changed rivers (being generalized to rectilinear positions) are their rectilinear propagation to circle the MURS from mainly radial to MURS. So, the concentric-radial (so the east. MURS could be an ancient giant impact cra- named ‘broken plate’) structure take place within the ter, which affected the geologic development of the MURS. Ural Mountains linear range. .