Geowebinar Insights

The study examines the kinetics of rod and ball milling of iron-bearing ores from the Egorskoe deposit. Experiments were carried out under conditions close to industrial practice, using sieve and mineralogical analyses.

Results show that rod milling ensures more intensive ore breakage at the initial stage, while ball milling proceeds more gradually and leads to higher mineral liberation.

Magnetite liberation in ball mills reaches 90–95%, compared to 83–86% in rod mills. In terms of specific productivity of the –0.71 mm size fraction, ball mills outperform rod mills by about 50%, with energy consumption being 1.5 times lower.

It is concluded that a combined milling approach is optimal: rod milling for coarse material and ball milling for fine material. This combination significantly improves ore preparation efficiency for subsequent beneficiation.

The study is based on spectral analysis of more than 1,700 samples from the Verkhne-Chemsk and Tainsk prospects of the Altai-Sayan fold belt. Comparative analysis of petrogenic elements revealed stable geochemical relationships that characterize ore-bearing rocks.

At the Verkhne-Chemsk site, Cu-Mo mineralization is associated with felsic intrusive rocks and potassium metasomatites. Maximum concentrations of copper (up to 3%) and molybdenum (up to 1%) occur in zones enriched in potassium and zirconium.

At the Tainsk deposit, vein and stockwork mineralization is hosted by granitoids and ultrapotassic rocks. Gold reaches up to 2.5 g/t, concentrated in K-bearing beresites and rhyolites. Sodium metasomatites contain only weakly anomalous values.

The results show that K/Na and Ti/Zr ratios are reliable indicators of ore potential. Their application in predictive studies allows early identification of prospective mineralization zones and clarification of genetic features of ore systems.

The study analyzes the geological structure and mineral composition of the Pizhem titanium ore deposit, highlighting rare-metal and rare-earth mineralization. Special emphasis is placed on the synformal structure of ore bodies, which confirms its genesis as a primary rather than placer deposit.

Two sandstone units are distinguished: the lower oxidized red-colored and the upper gray-colored, containing ilmenite and accessory minerals. Proven reserves amount to 300 Mt of ore with an average TiO₂ content of 4.27 %, while prognostic resources reach 7 Bt, ranking the deposit among the world’s largest.

The mineral assemblage includes ilmenite, ferruginous rutile, pseudorutile, leucoxene, culorite, zircon, and monazite. Hydrothermal alteration at 300–400 °C transformed ilmenite into other titanium minerals. Lamprophyres likely acted as the main titanium source, while zircon and monazite could have originated from granite batholiths.

Rare-earth elements are concentrated in culorite and monazite, dominated by neodymium and lanthanum, respectively. Zircon is often overgrown with xenotime, further enhancing ore value. Isotopic data indicate multiple mineral-forming stages between 0.6 and 1.5 Ga. The high content of rare and rare-earth metals makes the deposit strategically significant for Russian metallurgy.

The reign of Boris Godunov illustrates the complex interplay between political processes and natural disasters that shaped the fate of Muscovy at the beginning of the 17th century. His rise to power began under Ivan the Terrible and was consolidated through the marriage of his sister Irina to Tsar Fyodor Ioannovich.

Godunov introduced reforms, strengthened trade and industry, expanded into Siberia, and established new towns and fortresses. With his support, the port of Arkhangelsk was founded, becoming Russia’s gateway to the Arctic and a hub of international trade. He fostered contacts with Europe, invited architects, physicians, and scholars, and even planned the establishment of Moscow University.

The most dramatic event of his time was the 1600 eruption of the Huaynaputina volcano in Peru, which triggered global cooling and the famine of 1601–1603. Harvests failed for three consecutive years, and millions perished in Russia. The natural crisis coincided with political instability and the emergence of False Dmitry I, which undermined Godunov’s rule.

Although his reign ended in tragedy, Godunov’s reforms in education, trade, construction, and the military foreshadowed Peter the Great’s modernization and laid the groundwork for Russia’s future transformation.

The study presents results of 3D electrical resistivity tomography applied to the Cheburashka and Saratovskaya kimberlite pipes, exposed at the surface and hosted by carbonate formations. The survey revealed contact zones, deformation of host rocks, as well as brecciation, serpentinization, and calcitization effects.

Fieldwork was carried out in 2023 using the Scala64K15E multi-electrode system. An optimized acquisition scheme with three parallel profiles enabled full-scale 3D tomography and accurate reconstruction of the geoelectrical structure.

Inversion results showed low-resistivity anomalies corresponding to the geometry of the kimberlite bodies. At Cheburashka, anomalies reach 30×30 m and expand with depth; at Saratovskaya, a vertical cone-shaped conductive zone was identified. The results confirm the efficiency of this methodology for kimberlite exploration and for refining anomalies detected by other geophysical methods.

The Central Research Institute of Geological Prospecting (TsNIGRI) has developed a methodology for predicting and delineating diamond-prospective areas, based on the sequential use of geological, geophysical, and mineralogical criteria. The approach moves from large-scale regional zones to more detailed targets, enabling the identification of areas potentially hosting primary diamond deposits.

Key regional factors include thick cold lithosphere, a powerful crust, reduced heat flow, and gravity anomalies. Testing of the method in the northeastern Siberian Platform demonstrated that such criteria reliably control the localization of industrial kimberlite fields.

Within this territory, the Olenyok diamond-prospective area was identified at the intersection of kimberlite-controlling zones. It is characterized by indicator minerals, dispersion halos, and placer diamond occurrences. Xenolith data additionally suggest relic mantle domains with preserved diamond potential.

Subsequent work outlined the Salaali area, comparable in size to a search-scale object. These findings substantiate the high prospectivity of the northeastern Siberian Platform for forecast and exploration studies aimed at discovering primary diamond deposits.

The Transbaikal fluorite province hosts numerous occurrences, yet their gold potential has long remained poorly studied. Of particular interest is the Tretyakovskoe gold-fluorite deposit, located within the Slyudinsky horst, where fluorite and gold mineralization are combined.

The area is composed of syenites affected by cataclasis, silicification, and fluorite alteration. Ore bodies are confined to fracture zones and consist of multiple quartz generations and two fluorite stages. Gold occurs as native forms, electrum, and rare minerals, while in oxidized zones it is associated with iron hydroxides.

Drilling data indicate an increase in sulfide content with depth, confirming the multistage character of ore formation. Magnetite ore fragments with zircon and apatite yielded a U–Pb age of ~277 Ma, corresponding to regional rift-related magmatism. Geochemical and thermobarometric studies demonstrate distinct genetic processes for fluorite and gold mineralization, although they share similar rare-earth element distribution patterns.

Within the ore field, fluorite, gold-sulfide, quartz, and zircon-titanomagnetite mineralization coexist. This complex assemblage suggests a polygenetic nature of the deposit, reflecting a multi-stage history of ore genesis.

The study evaluates the potential of garnet and vesuvianite as geochronometer minerals. Garnet reliably records the age of alkaline ultramafic rocks in several magmatic provinces, including the Kola Peninsula, Maymecha-Kotuy, Eastern Sayan, Western Udana, and Sangilen, and also occurs in post-collisional contact formations. Its resistance to overprinting processes and capacity to accommodate uranium make garnet an effective tool for reconstructing stages of ore formation.

Not all garnet varieties are suitable: pyrope and almandine lack the structural ability to incorporate uranium, while andradite from gold deposits in the Gornaya Shoria region is uranium-poor.

Vesuvianite minerals also show promise for U–Pb geochronology, but their application is complicated by high common lead contents. Methodological solutions include isochron approaches and corrections based on co-genetic sulfide isotope compositions. A key selection criterion is the presence of boron in the crystal structure (viluite type).

Concordant age estimates for the Vilyui deposit (~250 Ma), together with results from the Norilsk district and the Canadian Shield, confirm the joint use of garnet and vesuvianite as reliable geochronometers. These findings provide new perspectives for reconstructing mineral-forming conditions and the evolution of ore systems.

The Burpalinsky massif, part of the North Baikal alkaline province, was studied through geological, geochemical, isotopic, and geochronological methods. It displays a concentric-zonal structure and is mainly composed of alkaline syenites, including nepheline-bearing varieties.

Rare earth element patterns reveal enrichment in light REEs and a weak negative europium anomaly, with nepheline syenites showing higher concentrations compared to other rock types. Sr–Nd and Pb isotope data indicate complex interactions between magmatic melts and host rocks, pointing to a mantle source enriched in early stages of the Siberian craton’s lithosphere evolution.

U–Pb zircon dating yielded crystallization ages around 389 Ma. Ar–Ar ages from amphibole, phlogopite, and feldspars reflect post-magmatic uplift and cooling, with feldspar systems closing about 15 Ma later. Thermobarometric estimates (2.5–3 kbar, ~10 km) align with a geothermal gradient of 25–30 °C/km.

These findings reconstruct the sequence of crystallization, depth of emplacement, and highlight the significance of mantle–crustal interactions in the massif’s evolution.