Main Regularities in the Localization of Mineralization in the Olkhovskoye Ore Field
Abstract Generated abstract
This paper examines the structural controls on sulfide and quartz-sulfide mineralization in the Olkhovskoye ore field. It argues that ore localization is governed primarily by the geometry and renewal history of fault and fissure systems associated with a regional anticlinal structure, a synclinal fold, and a Lower Paleozoic granodiorite intrusion, while host-rock lithology mainly influences ore-body composition and structure. The study identifies regularities linking ore bodies to repeatedly reactivated fissure directions, intrusive contacts, and intersections or junctions of fissure systems with contrasting dips, especially near contacts between limestone, effusive-sedimentary rocks, dikes, granites, and hornfelses.
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Main Patterns of Ore Localization in the Olkhovskoye Ore Field
D. G. Gogiberidze (Krasnoyarskzoloto)
The principal factor in the localization of ore mineralization at the deposits of the Olkhovskoye ore field is the structural features of their geological framework.
The deposits are developed in the area of virgation of the region’s main anticlinal structure, the two branches of which form a synclinal fold of general NW strike, pierced in its core by a Lower Paleozoic granodiorite intrusion, and are controlled by a complex system of faults. The clearly expressed tendency of the deposit toward the intrusive contact is also explained by the characteristics of the development of fault tectonics. The mineralization is represented by sulfide and quartz-sulfide ore bodies of complex form, occurring in Chibizhek limestones ($Cm_1$), effusive-sedimentary rocks of the Osinovskaya suite ($Cm_{1-2}$), and granodiorites. The character of the enclosing rocks affects chiefly the composition and structure of the ore bodies, and only to a slight degree their distribution.
In the distribution of faults and of the mineralization associated with them, the following patterns have been identified:
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The orientation and spatial position of tectonic fissures and zones reflect the main features of folding. The principal features of fracture tectonics were established already during the process of folding. All subsequent stages in the development of the deposits were accompanied by tectonic movements that did not introduce substantial changes into the conditions of occurrence and distribution of the fissures, but only selectively renewed the old directions. Faults are manifested most intensely near the contact between the Osinovskaya and Chibizhek suites.
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The degree of development of one or another system of ore bodies, with rare exceptions, is directly dependent on the degree of development of tectonic fissures of analogous direction. Only those systems of fissures that underwent repeated renewals, recorded by intrusions of dikes and granodiorites, are ore-bearing. The principal strike direction of the ore bodies corresponds to the strike of the main anticlinal structure, the granodiorite massif, most of the dikes, and the predominant direction of movement of tectonic blocks.
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Localization of mineralization occurs at places of intersection or linkage of at least two ore-bearing systems of fissures, as a rule with sharply different dip angles. Ore bodies often develop along contacts of different rocks, especially limestones with porphyrite dikes, granites, and hornfelses.