LITHOSPHERE, 2003, No. 19, p. 46

The primary mineral composition of aluminous rocks from the Kulazhin series of the Bragin granulite massif was reconstructed (using the Minlith program developed for the rock silicate analyses conversion). Results obtained and modular diagrams used have shown that initial rocks were clayey-terrigenous sediments of several types (clayey-sandy, sandy-clayey, carbonate-sandy-clayey and clayey ones) with some admixture of volcanogenic material. These sediments correspond to graywackes in their chemical and standard mineral composition. Deposits had been accumulated in the Bragin sedimentary basin both in hemipelagic conditions and nearly by the shoreline. A high proportion of clayey-sandy and sandy-clayey rocks in these sediments is indicative of a low degree of their maturity, which is seen in a widespread occurrence of fieldspar, hydromica, chlorite in primary deposits and may suggest the relief dissection in a sourceland, a low degree of chemical weathering, rather rapid denudation, trasportation and burial of terrigenous and volcanic-terrigenous material. Sourcelands of clastic material were volcanic formations of island arcs, on the one hand, and the continental type crust, on the other hand.

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