Litsa uranium ore occurrence (Arctic zone of the Fennoscandian Shield): new results of petrophysical and geochemical studies

Abstract

Mineralogical, petrophysical and geochemical studies have been carried out to determine the sequence and formation conditions of uranium mineralization within the Litsa ore occurrence (Kola Region). Mineralogical studies show the following formation sequence of ore minerals: uraninite – sulfides – uranophane, coffinite, pitchblende. Two stages of uranium mineralization are distinguished: Th-U (1.85-1.75 Ga) and U (400-300 Ma). The distribution of physical properties of rocks in the area is consistent with the presence of two temporal stages in the formation of mineralization with different distribution and form of uranium occurrence in rocks. The factors that reduce rock anisotropy are the processes of migmatization and hydrothermal ore mineralization, which heal pores and cracks. Fluid inclusions in quartz studied by microthermometry and Raman spectroscopy contain gas, gas-liquid and aqueous inclusions of different salinity (1.7-18.4 wt.% NaCl-eq.). According to homogenization temperatures of inclusions in liquid phase, the temperature of the Paleoproterozoic and Paleozoic stages of uranium mineralization at the Litsa ore occurrence is ~ 300 and 200 °С, respectively. Correlations of the spatial distribution of elastic anisotropy index with an elevated radioactive background allow using this petrophysical feature as one of the prognostic criteria for uranium and complex uranium mineralization when carrying out uranium predictive work.

Evaluation of Displacements Caused by Strike-Slip Deformations Using Correlation Characteristics Based on Potential Field Data

“…Tectonic-magmatic and disjunctive factors associated with faults, including strike-slip nature, affect the localization of orebearing structures [Alekseev, 2020[Alekseev, , 2021. The structure of ore bodies is often controlled by shears [Arkadiev, 1969;Movchan et al, 2022], since emerging spalls and cracks form a void space for ore deposition in a well-permeable zone [Il'chenko et al, 2022;Yakovleva et al, 2022]. Tectonic disturbances of shear nature form wide zones of increased rock fracturing, which can be significant in assessing the quality of facing stone [Isakova et al, 2021], in studying the stability of structures or mine workings [Kazanin et al, 2021].…”