Hipergeniczne przeobrażenia skał intruzji suwalskiej

Abstract

HYPERGENIC ALTERATION OF ROCKS OF THE SUWAŁKI INTRUSIONSummaryWeathered products of three main rocks of the Suwałki intrusion, i.e. norite, anorthosite and gabbrodiorite have been investigated. The relatively slightly developed weathering zones of these rocks affected during a long period from the Middle Proterozoic to the Buntsandstein by hypergenic environment should be related to allitization and ferrallitization processes proceeding under conditions of warm, periodically also dry climate. Horizons of more altered saprolite were probably eroded together with sedimentary cover during Permian denudation.Mineral composition of the hypergenically weathered products differs to, some extent accordingly with the mother rocks. Montmorillonite and amorphous hydrous oxides of iron are the main products of hypergenic alteration of norite. In the weathered anorthosite there occur kaolinite and montmorillonite, accompanied by amorphous iron compounds. Altered gabbrodiorite consists mainly of disintegrated primary minerals, and of small amounts of kaolinite, montmorillonite, hydrobiotite and chlorite.Due to secondary mineralization, the weathered products are enriched in CaO and NaCl. The zones of weathered rocks of the Suwałki intrusion reveal also the presence of the lower accumulation horizon of iron and of some trace elements such as Cr, V, Ni, Co and Cu.