ELEMENTS-IMPURITIES IN QUARTZ OF HYDROTHERMAL-METAMORPHIC AND HYDROTHERMAL-METAMORPHOGENIC-METASOMATIC GENESIS (SOUTH URALS)

Abstract

The relevance of the study is caused by the study and involvement of quartz-vein formations of various genetic types in the technological redistribution. Purpose: to determine the content of impurity elements in quartz of different genetic types and the degree of its suitability for obtaining high-purity quartz concentrates. Objects: quartz-vein objects of hydrothermal-metamorphogenic-metasomatic type (Berkutinskaya vein, Bolotnaya vein) and hydrothermal-metamorphogenic type (Peschanoe occurrence, Tolstikha vein, Novotroitskoe deposit). Methods: LA-ICP-MS spectroscopy of impurity elements, microscopic studies of quartz, estimation of P-T parameters of mineral formation. Results. It was found that veins of hydrothermal-metamorphogenic-metasomatic type are composed of multi-grained granular transparent, translucent, icy, sugar-like quartz, while quartz-vein objects of hydrothermal-metamorphogenic type are veins of execution and consist mainly of milky-white quartz. Quartz-vein formations of two genetic types differ in geological localization conditions, mineral formation temperatures, granulometric characteristics, the presence and location of mineral and fluid inclusions, as well as the content of the main petrogenetically informative elements-impurities (Li, Na, Mg, Al, K, Ti, Cr, Mn, Fe, Ni, Cu, Zn). It is shown that hydrothermal-metamorphogenic quartz is characterized by lower (288–410 °C) formation temperatures compared to hydrothermal-metamorphogenic-metasomatic quartz (415–519 °C), at close pressure values (2–4 kbar) and higher content of impurity elements (up to 535 g/t). The purity of quartz grains of hydrothermal-metamorphogenic-metasomatic genesis is associated with repeated exposure to the processes of metamorphism and metasomatosis, in which mineral and fluid inclusions were displaced from quartz grains into the intergranular space. The minimum values of the element content according to LA-ICP-MS spectroscopy are close to the values for the content of elements in the structural form and do not exceed 5–12 g/t for all types of quartz, with the exception of milky-white quartz of Peschanoe occurrence (up to 25 g/t). The minimum values for the content of elements-impurities in quartz show the limit of its enrichment and allow using a multi-stage enrichment system to obtain quartz concentrates of high purity.

Keywords

• quartz
• la-icp-ms spectroscopy
• high-purity quartz
• trace element composition
• metamorphism
• metasomatosis
• mineral impurities
• fluid inclusions