Lazuritic mineralization of the Badakhshan massive

Lazurite rocks of the Badakhshan massif, which is located in the south of Central Asia at the junction of two folded structures of the Southwestern Pamir and East Hindu Kush, are considered. On the example of the Sary-Sang, Lyadzhvardara and Goron occurrence, structural-textural features and the mineral composition of the main, secondary and accessory minerals of lazurite rocks are described. The main studies performed are spectral, X-ray structural, chemical analyzes, allowing to reveal their typomorphic features. The formation of lazuritic metasomatites mainly occurs at the regressive stage of metamorphism, which leads to the removal of volatile components (Cl, CO2, S) from evaporite strata with high chemical potential of potassium and sodium and the inert behavior of aluminum and magnesium. The lazurite deposits of the Badakhshan massif have a similar geological structure, but are characterized by a number of mineralogical and geochemical features that affect the scale of the deposits and the quality of lazurite raw materials. Minerals of lazuritic rocks (lapzurite, diopside, phlogopite, clinohumite) often inherit the chemistry of the rocks being replaced, which is reflected in their chemical composition. The concentration of typomorphic impurity elements (Ba, Be, Sr, Ti, Mn, Fe, Zr, Pb) in the minerals of the Lyadzhdara deposit and Horon occurences shows different degrees of metamorphic and metasomatic transformations of the bumi-nised bodies of aluminosilicate rocks. In addition, an important role has a different degree of dislocation and fracturing of rocks. For example, in the Lyadzhvardara field, lazurite mineralization is observed near the nuclear part of the anticline and the isocline that complicates its upturned isocline, and the Sary-Sang deposit linear bodies of lazuritized boudins are traced along tectonically weakened zones. Thus, the main search criteria and signs of zones with lazurite mineralization in the region are:1) confined to the Precambrian complex of magnesian marbles, metamorphosed under the conditions of the amphibolite and granulite facies; 2) the enrichment of marbles with primary sedimentary sulfur; 3) the presence in the marbles of the bodies of aluminosilicate igneous rocks of moderately acidic and acidic compositions, as well as boudinated veins of aplites and pegmatites; 4) the presence of alkaline minerals in the underlying meta-morphic and Boudins of igneous rocks; 5) the nature of fracturing and the intensity of metasomatic processes.

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