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Unique Magnetite deposits (Sokolovskoe, Sarbaiskoe, Kacharskoe) are revealed in Western Kazakhstan. The deposits are developed as the submeridional iron-ore zone along Eastern periphery of Hercynian Urals-Mulgodzhar folded belt at the turn of Pre-Cambrian-Caledonian folded system in northwest part of Central Asia. Iron-ore the belt was formed at the Riphean oceanic crust, overlapping by the Vend-Early Paleozoic carbonate-terrigenous sediments. The deposits of this belt have an Early Carboniferous postoceanic age. These deposits were formed after Hercynian oceanic crust consolidation of Urals-Mulgodzhar paleoocean along perioceanic rift zone. Andesite-basalt-gabbro-dioritic magmatism was showed there.
The new model of skarn-magnetite ore formation was developed. Tectonomagmatic processes were concentrated along perioceanic rift zones at the postoceanic, but preorgenic-collision stage. It was caused the development abyssal andesite-basalt magma chamber on the boundary "top mantle-oceanic crust". The opening of the chambers along rift structure caused the development of volcanism. The subsequent consolidation of volcanic processes was resulted to localization of magmatism in abyssal focal area. This process is fixed by small gabbro-diorite intrusions. The Na-Si-Fe solutions were segregated in abyssal focal magma zone. These solutions rose upwards after gabbro-diorite intrusions and formed metasomatic ore bodies in favorable carbonate-dolomite-andesite-basaltic section. The Si-Na-Fe solutions were isolated from andesite-basalt-gabbro-dioritic magma in consequence of early crystallization basic plagioclase and Ca-Mg femic minerals. After that these solutions were concentrated in the basis plutonic magma chamber by means as gravitational accumulation of Fe, and Fe expression together with easy petrogenetic elements (Na, Si). The marked factors caused the formation natrium - siliceous fluids enriched by Fe in a bottom magma column. These fluids rose upwards after small gabbro-diorite intrusions, and were located along theirs near-contact zones.
Thus, the formation gigantic deposits of torgai type does not require the addition of intratelluric iron-bearing solutions or granitization of gabbro-andesite-basalt substratum by solutions. On the basis of conception about separation of alkaline-siliceous-ferriferous fluid-melt from initial basalt magma system the magnetite ore formation is caused by crystallization fractionating of basic magma along anorthositic trend of evolution. Early isolation Ca, Mg and Al from Fe, Si and alkalis and the development of residual alkaline-siliceous solution with high content of ferriferous is noted there. Only solutions, enriched by Fe, could form such gigantic deposits.
The developed model of iron-ore deposits supposes the presence of the large oviform-bowl-shaped depression structures at the matle-basalt substratum. The axial parts of such structures are enriched by iron and fixed by gigantic deposits.
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