Severouralsk Bauxite Region

a region of bauxite deposits located in the vicinity of Severoural’sk, Sverdlovsk Oblast, on the eastern slope of the Urals.

The presence of bauxites was discovered in 1931 by the geologist N. A. Karzhavin. Bauxites are encountered in a belt extending for 150 km in a north-south direction. The region comprises, for example, the Krasnaia Shapochka, Kal’ia, Cher-emukhovo, Kedrovaia, and Sos’va deposits. The first bauxites (several tons) were mined at Krasnaia Shapochka in 1934. The region is linked by a branch railroad line to the city of Serov.

In color the bauxites are red or, less often, gray or greenish gray. They occur on the karstic surface of limestones of the Lower Devonian and are covered by limestones of the Middle Devonian. The ore bodies have the character of sheet deposits that slope downward toward the east at an angle of 35°–45°. The thickness of the bauxite layer varies from 0 to 10 m and in rare cases is as great as 30 m. The country rocks are water-bearing to a high degree. Analysis shows the bauxites to be of high grade: 50–60 percent A1₂O₃, 2–7 percent SiO₂, 20–25 percent Fe₂O₃, 2.0–25 percent TiO₂, and 12–13 percent H₂O; in some places, calcite and pyrite impurities are also encountered. Dia-spore is the most important mineral constituent of the bauxites; boehmite bauxites and mixed types—usually with hematite —are found less often.

According to one hypothesis, which was made by A. D. Ar-khangel’skii, the bauxites of the region are sedimentary formations of a Devonian sea. Another hypothesis, proposed by G. 1. Bushinskii, sees the formation of the bauxites as occurring under the conditions of a tropical climate. A chain of islands composed of basic rocks (basalts) was once located to the west of the region. The rocks’ laterite crust resulting from weathering was eroded by water, and the material of the crust was carried to karstic depressions, where it was deposited in the form of bauxites. The depressions were later covered by strata of marine carbonate rocks.

The bauxites of the region are regarded as among the highest-grade bauxites in the world. They are used primarily by the Krasnotur’insk and Kamensk-Uralskii aluminum plants of the Urals. Extraction of the bauxites from the earth is carried out by underground mining. The development of deep deposits, however, is hindered by the difficult hydrogeological conditions. The mining operations in the region have led to the construction of the city of Severoural’sk and a group of workers’ and urban-type settlements, including Kal’ia and Cheremu-khovo.