Formacje metalogeniczne przedpermskich utworów platformy wschodnioeuropejskiej

Abstract

METALLOGENY OF THE PRE-PERMIAN FORMATIONS OF THE EAST EUROPEAN PLATFORMSummaryThe East European platform extends east of the Teisseyre line (Poland) as far as to the Ural mountains (USSR). It is built of two principal stages - the crystalline basement and the Proterozoik – Palaeozoic - Mesozoic platform cover. The Archaean rocks are devoid of significant economic deposits, while gigantic iron ore deposits of Early Proterozoic age occur in shields and old platforms such as the Ukrainian shield and the Kursk Magnetic Anomaly (Figs. 1 and 2). Basic intrusions were formed in the Middle Proterozoic and ilmenite-magnetite ore deposits are related to those of anorthosite composition (the Caga deposit in the Baltic shield and the Krzemianka deposit in NE Poland). The Pre-Permian sedimentary cover contains several metallogenic formations. The fluorite and zinc-lead mineralization in Byelorussia originated during the Vendian metallogenic period, while the phosphorite deposits in the Peribaltic zone (USSR) and the molybdenum-vanadium mineralization (Fig. 3) in the Białystok area (Poland) are of Tremadocian age. The Devonian metallogeny produced several formations; the main ore districts are shown in Fig. 4:a - the ferriferous formation is of Givetian (Voronezh anteclise, Bashkir and Tatar Autonomous Socialistic Soviet Republics) of Frasnian (on the slope of the Voronezh anteclise) and of Famennian age (Orel area);b - the copper-bearing formation occurs in Lower Devonian fluvial-lacustrine sands (Dniester area) and in Upper Devonian (Frasnian) littoral and lagoonal deposits (the middle Cyma river);c - the zinc-lead formation is of Lower Devonian age in the Peri-Dniester area, Middle Devonian in Estonia, Latvia and the Briansk district, and Upper Devonian in the Orel district;d - the saliferous formation occurs in the upper Devonian sediments of the Dnieper-Donets and Pripet depression (Figs. 5, 6, 7). The deposition of sulphates commenced in the Givetian, but the principal salt masses were formed at the close of the Frasnian and in the Famennian. In the Pripet depression the thickness of the salt beds range from 1 000 to 3 500 m. The upper salt-bearing beds are built of alternating rock salt and potassium salts layers. The Viséan bauxite-bearing sediments are worth mentioning. Numerous bauxites, refractory clays and iron are deposits (Fig. 8) were formed in the Precambrian platform. They are redeposited weathering products of the Devonian and Cambrian basement and of basic Proterozoic rocks. The most important bauxite deposits are those of the North Onega, Tikhvin, South Timan, Moscow, Byelgorod, and Pripet areas.