Yaremchuk Y. Clay minerals of Phanerozoic evaporites as indicators of secular variations in seawater chemistry

Object of investigation: evaporate formations of Ukraine - Devonian and Permian (Dnipro-Donets Depression) Jurassic (Foredobrodgea), Neogene (Carpathian region), and the Phanerozoic evaporites of individual regions of the World based on literary material; subject of research: clay minerals of pelitic fraction of water-insoluble residue of different-aged marine evaporites at different stages of brine concentration; objectives of studies: to establish the differences in mineral and chemical composition and structural peculiarities of clay minerals of evaporites derived from concentrated seawater of SO4-rich and Ca-rich types; methods of investigation: SEM, X-ray diffraction, complex thermic and chemical (силікатний) analyses; practical value: secular variations in composition of clay minerals of Phanerozoic marine evaporites concordant with variations in seawater chemistry and with evolution in sedimentary rock formation became a new indicator for prognosis of minerals distribution; scientific novelty: regularity of secular variations of chemical and mineral composition of clay minerals of Phanerozoic marine evaporites is established. The regular character of modifications of clay minerals associations on three stages of brine concentrations is established for Neogene evaporites of Carpathian region and Permian of Dnipro-Donets Depression. It is established for the first time that peculiarities of chemistry and mineralogy of clays from rock salt depend upon brine concentration within one (halite) stage of evaporation.