Structural-Rheological Transformations of the Ore-Based Rocks of the Hannivka Molibdenum Deposit (Kryvyi Rih Formation).

Problem Statement and Purpose. This work is aimed at studying the rocks of the New Kryvyi Rih formation within the central part of the Hannivka deposit of Kryvbas. The latest data from prospecting and appraisal drilling of wells in this area made it possible to study in more detail the geological structure of the area and establish the nature of the spreading and distribution of ore zones. Data & Methods. The research was carried out using core material from exploratory drilling. When studying this object, along with classical geological research methods, tectonofacies methodology was used, based on a systemic principle and on a paragenetic basis. It took into account PT‑conditions and the rheological properties of geological environment in stress fields, depending on those conditions, as well as the mechanisms of dislocation transformations of rocks corresponding to those properties. Results. Using structural characteristics, the main features of the formation and transformation of rocks in ore-bearing mineralized zones have been established. The forms of occurrence of sulfide mineralization were described, and the conditions of their primary and secondary occurrence were also determined. The nature of structural and rheological transformations of ore-bearing rocks and their influence on the conditions of occurrence of molybdenum mineralization have been studied. The main rheological types of fault tectonics were identified and their influence on the mineralization process was analyzed. Several main types of occurrence of sulfide mineralization at the macrolevel, which were distinguished by qualitative and quantitative indicators, have been identified and described in detail. It has been established that within the Hannivka deposit, sulfide mineralization was clearly recorded from a depth of 150 m and could be traced to a depth of more than 400 m, and an increased concentration of molybdenite was observed in metatuffs and metalavas with overlain predominantly quartz veins. Moreover, ore minerals (molybdenite along with iron sulfides) were divided into two fundamentally different forms of distribution: primary and metamorphosed secondary. The types reflect the intensity of superimposed deformations, calculated using a specially developed tectonofacies scale.