Abstract:
The EPR method was for the first time used for studying composition, form, and structural transformations of paramagnetic impurities in major generations of halite from the zones of basic-rock-evaporite interaction. The main paramagnetic impurities in natural halites are Mn2+ and Fe3+ and dispersed organic matter. Isomorphous incorporation of Mn2+ into the regular lattice of NaCl is rather limited and was found only in sedimentary halites. The main form of stabilization of Mn2+ in hydrothermal and contact-metasomatic generations of halite are carbonate microphases. Ions Fe3+ concentrate in various forms: clusters, microphases, and independent hydrogoethite and goethite phases. An increase in the degree of contact metamorphism of salts leads to an increase in the dimensionality of Fe3+ accumulations. Ferromagnetic oxides and sulfides are stable in high-temperature contact zones. The dispersed organic matter is also specific in the EPR spectra of halites with a varying degree of metamorphism. The revealed peculiarities of the modes of incorporation of paramagnetic impurities into the real halite structure are a new typomorphic feature suitable for separation and correlation of halite-bearing associations and interpretation of the dynamics of metasomatic mineral formation.