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Tikhvinsk - Batkovsk, Sinensk, Podsosnensk, Malyavinsk, Yartsevsk, Zapolsk, Maksimovsk, Gorsk |
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Russia |
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Al
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Tikhvinsk group of bauxite deposits, which were discovered in 1916, are located 200 km to the SSE of St. Petersburg and are confined to a belt of Lower Carboniferous sediments on the north western limb of the Ploscow Syncline. More than 30 deposits define a near north-south zone some 260 km long, including Bat'kovsk, Sinensk, Podsosnensk, Malyavinsk, Yartsevsk, Zapol'sk, Maksimovsk and Gorsk.
The boehmite bauxite at Tikhvinsk was not suitable for treatment using the Bayer method and alternative treatment options had to be developed. Full development of the Tikhvin bauxite mine began in 1929 and in April 1934, alumina production from Tikhvin bauxite began at Dnepr.
The basement to these deposits copmprises a Late Devonian (Famennian) mottled group and two Lower Carboniferous sedimentary sequences. The Upper Devonian sediments comprise sandy, often micaceous, laminated clays of bluish-grey colour with lenses of sands and mottled sandstones. In the southern part of the region, the upper portion of the sandy clay sequence contains Tournaisian marl horizons, limestones, and dolomites.
The bauxite-bearing sediments are of Lower Carboniferous age and rest with an erosional break above the Devonian mottled clays and are also overlain by further mottled clays with lenses of sand, and in some cases by cobbly clays and other glacial deposits or by a soil-vegetation layer. These are in turn overlain by Lower Carboniferous sand-clay rocks with seams of limestone and rare dolomites, and finally by Quaternary clays and loams with cobbles of solid rock.
The bauxites are associated with aluminous clays that are developed along an erosional unconformity and appear to be largely developed as a Carboniferous palaeo-weathering profile within a Carboniferous sedimentary layer and the underlying Devonian basement. The pre-ore relief developed on the Devonian basement comprised a broad upland dissected by north-south trending river valleys with vertical reliefs of 10 to 30 and rarely 40 m. The length of these valleys varies from 1 to 4 km and rarely to 7 km, with maximum widths in the lower reaches of up to 500 to 1000 m, and minimum widths in the upper reaches of around 100 m. The ore deposits are restricted to these valleys and have similar dimensions.
The ore occurs as narrow elongate lens-like deposits with a simple weakly concave or uneven top surface and a downwardly convex floor. The mineralised layers follow the dip of the underlying Devonian sequences at 10 to 20 m per km and persist to depths of from 1 to 2, to 100 to 150 m, but is usually not more than 40 m.
Zoning within the bauxites display a concentric structure, with good~quality bauxites in the core of the deposit, replaced towards by allites and then by siallites, reflecting a gradual decrease in alumina and iron oxide, and increase in silica decreases from the core to the periphery of the deposits.
The bauxites are reddish-brown in colour, weakly sorted, and contain a substantial quantity of plant remains, and a large amount of secondary calcite. The bauxites include strong, friable and argillaceous varieties and display clastic, finely dispersed (pelitic), and oolite-pisolite textures.
The bauxites were formed from an original weathering crust of Devonian claysand comprise a gibbsite-boehmite-kaolinite mineralogy with varying ratios of the ore-forming minerals. The bauxites contain 35.7 to 48.8 wt.% Al2O3; 11.0 to 17.9 wt.% SiO2; 10.1 to 19.5 wt.% Fe2O3; 1.6 to 2.8 wt.% Ti02; and 0.6 to 10.3 wt.% CaO.
Alumina production from the Tikhvinsk deposits in 1994 amounted to 0.194 Mt of Al2O3.
This summary is drawn from Smirnov, V.I., (Ed.), 1977 - The Ore Deposits of the USSR; Pitman Publishing, v.1, pp. 311-313.
The most recent source geological information used to prepare this decription was dated: 1996.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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