Vol 55 Iss. 2

The widespread use of metallogenic studies of various scales and the need to identify large genetic communities of rocks and ore formations have led to the increasingly widespread use in the geological literature of the term formation in relation to mineral deposits. ...

The Sarbaiskoye iron ore deposit has been studied by many researchers. The most detailed subdivision of the section of the volcanogenic-sedimentary strata of the host rocks was made by V.M. Izoitko, who distinguished seven packages according to the prevalence of certain rocks. It was proved, contrary to I. A. Kochergin, that the so-called Western, Eastern and South-Eastern ore bodies represent a single ore body, separated by ore‑bearing tectonic disturbances. ...

The deposit lies among dislocated and metamorphosed sedimentary-volcanogenic rocks of Paleozoic age (Valerian Formation), which have a monoclinal bedding with a westward dip at an angle of 40 45°. The deposit consists of three stratiform ore bodies occurring conformably with volcanogenic-sedimentary rocks: Western, Eastern and Southeastern. The age of the ore bearing strata of the Sarbaiskoye deposit has so far been determined by foraminifera from the core of the well located near the Western ore body (Middle Upper Visean Lower Namurian). Our faunal discovery belongs to the tuffite horizon composing the hanging wall of the Eastern ore body. ...

The Sokolovskoye contact-metasomatic deposit of magnetite ores lies among sedimentary-volcanogenic rocks of the Valerian Formation monoclinally dipping to the east at an angle of 40-60°. In the southern part of the deposit, within the pit, the host rocks and magnetite ores have meridional strike and are tilted to the west at an angle of 70-80°, which is associated with displacement along the South Sokolov thrust. This thrust, dipping to the northwest at an angle of 45-48°, limits the ore zone of the Sokolovskoye deposit from the south. According to N. I. Rudenko, the tectonic structure of the deposit and its open pit part is blocky. In the west, between limestones and ores, N. I. Rudenko distinguishes a pre-ore meridional disturbance, which is considered as the main solution-feeding disturbance. Parallel to the main one in the central part of the ore zone is the Central meridional disturbance, extending only within the open pit. ...

Volcanic formations of Priargunye play a significant role in the metallogenic appearance of the region. A number of types of mineral deposits are paragenetically associated with them, for other deposits they are host rocks, in one way or another affecting the spatial distribution of deposits. ...

The area of the deposit in terms of structure belongs to the most tectonically complex area of the Sikhote‑Alin. The complexity of its structure is caused by multiple manifestations of folding, disjunctive and magmatic processes that took place almost continuously from the Upper Paleozoic to the Paleogene inclusive. ...

The wide development of geological research in volcanogenic areas contributed to the discovery of a number of deposits and ore occurrences of metals (Au, Ag, Cu, Mo, Pb, Zn, Sb, Hg, Bi, U, etc.) and nonmetals (alunite, corundum, sulfur). In turn, these discoveries attracted the attention of geologists to the elucidation of ore-bearing potential of volcanogenic formations in general and to the study of the peculiarities of formation of hydrothermally altered rocks with which the ore occurrences are associated, in particular. ...

The Zerendinsky pluton is one of the largest and most interesting granitoid massifs of Kazakhstan. The first information about the geological structure of the Zerendinsky massif was obtained in the late 19th century as a result of studies by G. G. Anzimirov, A. A. Krasnopolsky and others. In subsequent years, the works of I. S. Yagovkin, P. I. Preobrazhensky, A. S. Krasilnikov, E. D. Shlygin, P. N. Kropotkin, Yu. A. Bilibin and T. V. Bilibina laid the foundations of knowledge about the most general features of the structure of the massif, its morphology and age. More systematic and detailed studies began in 1949, when the staff of the North Kazakhstan expedition of the MGRI began to compile geological maps at the 1:200,000 scale in the territory of Northern Kazakhstan, including within the Zerendinsky massif. Generalization of the wide material obtained in the process of these works and additional studies allowed R. D. Gavrilin to establish three intrusive complexes among granitoids of the Zerendinsky massif. However, on the geological map compiled by him, the distribution of the isolated varieties is often erroneously indicated, and the separation of phases within the complexes is not sufficiently substantiated. This led to the fact that the dissection scheme proposed by R. D. Gavrilin was rejected by almost all the researchers who subsequently studied the Zerendinsky massif. The schemes of the listed authors differ from each other in many details, but are similar in the allocation of only two intrusive complexes. ...

Over time, more and more examples of rational interpretation of ore field structures have been accumulated, which significantly helps further prospecting and exploration work. Over the last ten years, the intensified development of this problem has also begun in application to crystal-bearing fields. Undoubted progress has already been achieved for the fields of crystal quartz veins (works by A. E. Karyakin, V. A. Smirnova and others in the Subpolar Urals). Interpretation of the structures of the fields of crystal-bearing pegmatites has not yet been completed and there is no unanimous judgment on the methodological basis necessary for this. ...

Extensive literature is devoted to the issues of hydrothermal alteration of host rocks at domestic deposits of rock crystal. Since the majority of rock crystal deposits are confined to quartz-bearing rocks, it is natural that sandstones, quartz-mica schists and various granitoids have been the main focus of attention of researchers. However, significant commercial accumulations of rock crystal are also known in carbonate rocks. Such is the case of one of the deposits in the Urals, which was studied for several years by V. D. Eshkin, who published a number of works on its geology, genesis and on the question of hydrothermal alteration of the host rocks.

Terrigenous sediments of Upper Jurassic age, represented by clay shales and sandstones, are developed within the Deputatskoye ore field (North‑East Yakut ASSR). The sedimentary strata forms a synclinal fold of near‑latitudinal strike, with the ore bodies of the Deputatskoye deposit proper confined to its northern gently dipping limb. Shale‑sandstone rocks are intruded by the Deputatskoye intrusion of granitoid composition, one of the outcrops of which is located southwest of the deposit. In the central part of the deposit, the contact of the intrusive massif was penetrated by a borehole at a depth of 377.4 meters. Numerous dikes of diabase and diabase porphyrites, quartz porphyries and lamprophyres are found in the deposit. The strike of the dikes is northeastern and latitudinal, less often northwestern, and the dip is steep to the north and south. The dikes of basic and acidic composition are pre-ore with respect to tin mineralization, while the position of lamprophyres remains unclear. During the formation of the Deputatskoye intrusive, shales and sandstones underwent contact metamorphism. According to the degree of intensity of metamorphic processes, three zones are distinguished, each of which rings around the previous one: 1) zone of intensive silicification, tourmalinization, sericitization, sometimes greisenization; 2) zone of silicification, chloritization, sericitization; 3) zone of weak silicification and sericitization....

Economic efficiency of exploration of any deposit depends on the correct choice of technical means and rational placement of the necessary number of exploration intersections. The latter is determined, as a rule, by the degree of variability of the main parameters of the field. ...

The Leningrad oil shale deposit is located in the west of the Leningrad Region and is the eastern part of the Baltic oil shale basin. The industrial oil shale bed (promplast) lies in the lower part of the Kuker stratigraphic horizon of the Middle Ordovician and consists of four convergent layers of oil shale, separated by interlayers of limestone. ...

The Pikalevskoye limestone deposit is located in the Boksitogorsky district of the Leningrad region.The deposit occupies a part of the northwestern wing of the Moscow Basin, which causes a weak dip of its constituent rocks in the southeastern direction. ...

Operational exploration of limestone at the Pikalevskoye deposit is carried out by drilling of core wells. According to the accepted methodology, first of all, the wells are drilled from the day surface on a square grid of 100X100 and 50x50 meters. The depth of the wells is determined by the depth of occurrence of sandy-clay rocks of the Venevsky horizon. In the future, to clarify the qualitative characteristics of limestone, the network of excavations is condensed to 25X25 meters. Wells on this network are passed after overburdening works from the surface of limestone. The depth of the wells is determined by the thickness of the carbonate strata. ...

Improving the quality of geological documentation can be achieved by photographing mine workings and then compiling photographic schemes that are used for primary geological documentation. This method is simple, but is possible when the reflectivity of the minerals composing the deposit is known, which makes it possible to select photographic materials and light filters that give the opportunity to obtain the most contrasting separation of minerals on the photo. ...

In the practice of calculation of reserves the rule has taken root that if there is a correlation between the content of a useful component and some other parameter, the average content should be determined by the weighted average method, and if there is no correlation - by the arithmetic mean method. This point of view was first expressed by N. V. Volodomonov and later supported by P. L. Kallistov, V. I. Smirnov, V. M. Kreuter, V. I. Kuzmin and others. However, N. F. Zalata and A. A. Petrov strongly argue that the weighted average method is erroneous and recommend that the average content be determined only by the arithmetic mean method. In the last paper L. F. Zalata connects the method of determining the average content with the type of asymmetry of the distribution of the useful component. V. I. Borzunov believes that the weighted average method is applicable only in the case of changes in content along a hyperbolic curve. In other cases he recommends to apply the method of arithmetic mean. V. A. Petrov proves that the weighted average method of determining the average content in the predominant number of cases gives a more satisfactory result than the arithmetic mean method. Experimental studies carried out on models of ore bodies by I. A. Zimin and E. M. Teplyakov, have shown that in some cases the weighted average method is more justified, and in other cases - the arithmetic mean method is. ...

The article under consideration by P. B. Vainerman and A. S. Smirnova, in our opinion, insufficiently objectively, and in some cases geologically incorrectly reflects some questions of conditions of formation and regularities of location of Transcaucasian deposits of technical agate. In this regard, we consider it necessary to discuss these issues in order to exclude subjective and poorly grounded ideas, which can mislead researchers. ...