2011

Тезисы международной конференции

Рудный потенциал щелочного, кимберлитового

 и карбонатитового магматизма

Abstracts of International conference

Ore potential of alkaline, kimberlite

and carbonatite magmatism

Geological-structural features of the spatial placing of uranium ore objects and kimberlitic-(lamproitic-) magmatisms within the Krivoy Rog-Kremenchug mineragenic zone

Kalashnyk G.A.

Exploration expedition № 37, State enterprise "Kirovgeologiya",

State Service of Geology and mineral resources of Ukraine

 kalashnyk_anna1@mail.ru

Krivoy Rog-Kremenchug deep fault is the boundary of the Kirovogradskiy (Ingul'skiy) and Middle Dnieprovskiy megablocks of the Ukrainian Shield. Krivoy Rog-Kremenchug mineragenic zone is unique. Rich deposits of iron, commercial objects of uranium, scandium, vanadium and mineralization of gold, copper, nickel, cobalt, lead, molybdenum and other mineral components in this zone are concentrated.

Industrial significance of the Krivorozhskiy uranium ore region is determined by Pervomaiskoye and Zheltorechenskoye deposits of iron-uranium formation in albitites. These deposits have already worked out. Non-industrial Kremenchuzke and Nicolo-Kozielskoye deposits and a numerous of uranium ore objects of different genesis is well established in this mineragenic zone. Iron and uranium ore concentration within the Krivoy Rog-Kremenchug fault zone are polychronic and polygenic (Gursky et. al., 2005). Relationship of uranium-iron in uranium ore objects of Kryvorozhzhya is very specific, although the process uranium ore forming has several common features with formation of uranium ore objects in albitites in the Kirovograd uranium ore region. Processes of alkali metasomatism of metamorphosed iron ores and iron-silica and silicate of enclosing rocks have wide spread occurrence in the Krivoy Rog-Kremenchug fault zone. These processes have led to a change in material composition of the ferruginous rocks. They are often characterized by intense enrichment by uranium of these formations, as well as Sc, V, Zr, TR (Gursky et. al., 2005).

Endogenous ore objects in the Krivoy Rog-Kremenchug mineragenetic zone have well-defined local structural position. They are located at the sites of intersection of regional Krivoy Rog-Kremenchug fault zone of first-order with fault structures of different orders of another direction, mainly latitudinal direction. Particularly, Zheltorechenskoye deposit is located in the junction of latitudinal Subbotsko-Moshorinskaya mineragenetic fault zone and the Krivoy Rog-Kremenchug fault, Pervomaiskoye deposit is located in the sites of intersection of Devladovskaya latitudinal fault and the Krivoy Rog-Kremenchug fault zone.

According to the authors, discretely localized occurrences of mineral concentrations are the result of the influence of the deep sources of ore components associated with the Krivoy Rog-Kremenchug mineragenic fault zone. Complex metallogeny of fault zone was formed due to the multiple participation of its individual parts in the several stages of tectonic-magmatic activation. This led to the formation along a fault of local favorable for the development of intensive and differentiated mineralization geological systems. Kimberlitic, lamproitic magmatism and explosive structure is also located along the main line of the Krivoy Rog-Kremenchug fault. Discordant mostly latitudinal tectonic faults (Subbotsko-Moshorinskaya, Devladovskaya and other) in the junction with Krivoy Rog-Kremenchug mineragenic zone exerted influence on the geological formation of the upper layers of the Earth’s crust of different stages. In complex, this ensured the stability of the ore-forming systems, the duration and completeness of the ore-forming processes, a strong differentiation of substances with repeated mobilization, redeployment and concentration of iron, uranium ore, and polymetallic metallogenic specialization of different components. It led to higher metamorphic and magmatic activity and entry of the juvenile substance, especially alkalis, volatiles and ore components with the physical and chemical characteristics of a wide spectrum.

In Kryvorizhzhya metasomatic altered iron ore are concentrators of rare, dispersed and noble metals. Calculated by K.F. Tyapkin on geological-geophysical data position of low bound of iron-bearing layers (4-6 km) of the Kryvorozhskaya structure underlines the presence of intercommunication of deep and near-surface ores (Integration…, 2008). Prerequisites to the formation of complex deposits along the Krivoy Rog-Kremenchug fault zone is founded on the richness of ore and volatile components of deep foci. Spatial combination of major uranium deposits and kimberlite magmatism in this region indicates the mantle nature of useful components for the uranium ore deposit. Kimberlitic-like rocks of Ternovskaya structure has content of CO₂ up 25.7% (Yatsenko et. al., 2002). This suggests a high kinetic energy of kimberlite magma intrusion the from the mantle depths. Wealth volatile deep magma foci caused the extensive development of the hydrothermal-volcanic and metasomatic activity. As a result of complex uranium-ferruginous (sometimes additionally scandium-vanadium) ore deposits were formed and the objects along the Krivoy Rog-Kremenchug fault. Probably, discrete ore concentration formed over the zone of intense degassing and sources of deep uranium-containing fluids. The juvenile nature of sources of uranium components are fixed by kimberlitic and lamproitic magmatism, which are spatially coincident with the mineralization of complex ore objects (Pervomaiskoye, Zheltorechenskoye deposits). Open cavity of the mantle penetration should be formed for the formation of rich uranium ore. This condition provides large masses of CO₂,  useful mineral components and the creation of other physical and chemical conditions of uranium mineralization. In Krivoy Rog uranium ore region, as well as Kirovograd uranium ore region  this condition is satisfied by geodynamic situation of local expansion. This situation is identified by dyke complex of ultrabasic alkaline rocks, in the first place by kimberlite magmatism (Kalashnyk, 2010).

The specific orientation of the most permeable areas of mineragenic zone any area is defined by the regional structure and local structural forms that are directly related to the processes of ore formation. The placement of endogenous deposits of different genesis is controlled by in this direction. Regional structural features of the Krivoy Rog-Kremenchug deep mineragenetic zone are highlighted on different structural levels. They are indicated by in a line placement of endogenous deposits of a wide range of content along deep Krivoy Rog-Kremenchug fault zone. This means that the juvenile sources of useful components play a main role in formation of these deposits. Rich endogenous ore accumulations of industrial content of different specialization, exclusively related to subcrustal sources (Pervomaiskoye and Zheltorechenskoye uranium deposits). Non-industrial ore objects of the fracture-vein type associated with the borrowing of useful components from the host rocks. They are formed by regenerating the previously formed ore accumulations. Differences in mineral and material composition of mineralization (monometallic nature of uranium mineralization in the Kirovograd uranium ore region and uranium-polymetallic mineralization nature of the Krivoy Rog uranium ore region) are due to polymetallic nature of the juvenile sources of ore components in the Krivoy Rog-Kremenchug mineragenic fault zone. Also they are due to combination of two factors ore specialization of foci (subcrustal (mantle) sources of useful components and borrowing useful components of the host rocks) led to the formation of complex polymetallic ore objects within the Krivoy Rog-Kremenchug mineragenetic zone. Kimberlitic and lamproitic magmatism is an indicator of feeder ore’s components of specialization foci from the upper mantle for ore concentrations in the upper structural level. Spatial superposed of kimberlitic magmatism and uranium ore formation discovered in Krivorozhskiy and Kirovogradsky uranium ore regions (Kalashnyk, 2010).

Spatial superposed within the Krivoy Rog-Kremenchug fault zone industrial iron ore, uranium, polymetallic, gold mineralization is a single homologous series of ore formations. They are derived from continuous-intermittent post-volcanic processes. High polymetallic ore saturation of Krivoy Rog-Kremenchug fault indicates the specificity of the geological history of development of this zone. It is associated with the evolution of system of magma foci on the different depths of Krivoy Rog-Kremenchug mineragenic fault zone, including the mantle levels, which are fixed by kimberlitic magmatism.

References:

Gursky D.S., Esipchuk K.E., Kalinin V.I., Kulish E.A. and other. Metallic and non-metallic minerals of Ukraine. Volume 1. Metallic minerals. Kyiv-Lviv. "Center of Europe." 2005. 785 p. (in Russian).

Integration of geophysical methods / under editor K.F. Tyapkin. 2008. Donetsk. "Veber". 336 p. (in Russian).

Kalashnyk G.A. Mineragenic potential of latitudinal fault zones of the Ukrainian Shield (in Russian) // Mіneral Resources of Ukraine. 2010. № 3. Р. 24-36

Yatsenko G.M., Gursky D.S., Slivko Y.M. and other. Diamond-bearing formation and structure of the southwestern outskirts of the East European platform. Kiev: UkrSGRI. 2002. 331 p. (in Russian).