Abstract:
The geological position and structure of the large uranium-bearing Novoukrainsk ore field, confined to the Novoukrainsk granitic massif in the central part of the Ukrainian Shield, is reviewed. It is shown that the distribution and main regularities of uranium-bearing albitites in compositionally homogeneous granites were defined by structural factors, the main of which was represented by the Novokonstantinovsk tectonic zone. The Novoukrainsk ore field is confined to a part of an arclike bend of the Novokonstantinovsk tectonic zone complicated by contiguous intersections with regional faults of various orientations. The inner structure, succession of the formation of various faults of the Novokonstantinovsk zone, and nature of tectonic deformations in the zone were studied. It is shown that the tectonic zone originated and developed as a deep-seated long-lived fault of the crystalline basement. The zone was formed in the period of the Early Proterozoic tectono-magmatic activization of the Ukrainian Shield simultaneously with the formation of the Novoukrainsk granites in conditions of ultrametamorphism and ductile deformations. In the epoch of the Late Proterozoic tectono-magmatic activization, faults of the Novokonstantinovsk tectonic zone were subjected to repeated movements accompanied by linear and brittle deformations, metamorphism of the greenschist facies, and alkaline metasomatism accompanied by uranium ore formation. On the basis of conditions of the ore localization, it is shown that the scale of the uranium ore formation within the ore field directly depended on the intensity and spatial superposition of tectonic deformations in ore-controlling faults.