Geochemical-mineralogical factors of anhydrite-to-polyhalite evolution: implications to seismic-water-H2S hazards in mining and quality of sulphate components in building materials

Mining exploitation of cement/concrete components experience sometimes problems caused by tectonic process and water hazards during mining of polyhalite-bearing sulphate rocks. Polyhalite is a hydrated K-Mg-Ca sulphate mineral of high economic significance, including construction materials industry. On the other hand, traditional tectonic analyses for seismic/water events prediction, often emphasize external forces and mining-induced stress relaxation. They rarely arise questions on primary origin such forces. Potential cumulation of stress, resulted from internal geochemical-mineralogical origin of such forces, of large-scale compression/tension and mass-movement are often neglected. A universal, approach here concerns the role of geochemical control of volume-temperature variations combined with post-sedimentary transformation of anhydrite to polyhalite what apparently implicates substantial problems during any mining carried out in anhydrite bodies. Such 100% transformation: a) increase volume of elemental cells by c.a. +137,76 %, b) is exothermic, c) elevates pressure d) results stress, e) implicates deformations: compressive inside and tensile outside, f) forms elevations, g) results chaotic K/Ar ages with millions of years discrepancies, h) may result sesimtectonic-water-H2S combined hazards and apparent subsidence. Such transformations have critical implications for general view in tectonic forces and formation of deposits, geological documentation and mining of them, particularly in addressing water, stability hazards during resource extraction and environmental issues [subsidence/deformations, earthquakes, water regime/pollution/salinisation, H2S etc]. The geochemical reactions, accelerated by deep-mine drainage activity, may result in fast [even days/years] geochemically negligible anhydrite-to-polyhalite volume-grow transitions, which however results in seismotectonic- water- and H2S-hazars, especially in anhydrite-dolomite-halite mining systems. They are pivotal in shaping mechanical properties of rocks and their deformations and movement. The study underscores the need for integrated geochemical and structural analyses to better understand these phenomena and mitigate associated risks from exploration to resource extraction [economy, safety, water-brine-subsidence environmental hazards] and geoengineering.