Vol 65 Iss. 2

One of the most characteristic features of activation zones is the clearly expressed independence of the structural plan of the activation period relative to the structural plan of the basement. In the territory of Eastern Transbaikalia, chains of depressions associated with Late Mesozoic activation, dike belts, chains of intrusions and volcanic vents cross the boundaries of basement blocks with different composition and different geological history.

Many tectonic geologists, as well as specialists dealing with issues of general and regional metallogeny, consider it necessary to distinguish a special type of continental crustal structures, different from platform and geosynclinal structures. However, the extent of such structures, the content and nature of the processes generating them, and their place in the general history of crustal development are considered from completely different, often opposite points of view.

When studying hydrothermal deposits, the attention of researchers, first of all, is attracted by vein bodies diverse in composition and structural-textural features. Elucidation of the conditions and processes of their formation is in this case the main and rather difficult problem.

The Udachnaya kimberlite pipe is located on the southern slope of the Anabar anteclise. The sedimentary section hosting the pipe is represented by carbonate (calcareous-dolomitic) sediments of the Cambrian and Upper Proterozoic up to 4000 m thick.

The Sokolovskoye magnetite ore deposit is one of the largest in the Turgai Trough. It lies among sedimentary-volcanogenic rocks of Lower Carboniferous age (C₁ v + n), dipping monoclinally to the east at angles from 40 to 60°. Structurally, the deposit is confined to the eastern limb of an anticlinal fold.

Tin ores of the Deputatskoye deposit (northeastern Yakut ASSR) were formed during five stages: quartz-tourmaline, cassiterite-silicate-quartz, quartz-sulfide, quartz-carbonate-sulfide, and carbonate. Cassiterite was deposited from solutions of all stages, but its main mass was formed in the second stage in close association with vein quartz, tourmaline, fluorite, chlorite, and wolframite. Cassiterites of the second (main productive) stage were the subject of our study.

Researchers studying the regularities of the location of gold mineralization within ore fields or individual ore bodies of deposits of the poorly-sulfide formation often encounter serious difficulties.

In the practice of predicting mercury deposits, the ore-formation criterion does not find proper application, although attempts at systematization of mercury deposits on a formation basis have been made repeatedly. A number of works by Academician V. A. Kuznetsov and other researchers are devoted to this issue.

The study of distribution patterns of trace elements is a necessary addition to the genetic and industrial characterization of ores and is of particular importance in connection with the problem of their integrated use. In ores of the Sarbaisky deposit, iron as the leading ore-forming element is accompanied by a significant number of trace elements, the most important of which is cobalt.

The article deals with the peculiarities of distribution and behavior of manganese in a genetically related series of Caledonian granitoids of Northern Kazakhstan, combining three intrusive complexes: Middle–Upper Ordovician–Krykkuduk (granodiorites), Lower Devonian–Borovsky (normal biotite granites), and Middle Devonian–Balkashinsky (leucocratic and alaskite granites).

The deposit is located in the western exocontact of the microcline granite massif and is confined to a brachyanticline composed of various crystalline schists. Attention should be drawn to the following features of the geological structure of the deposit...

Drilling of boreholes in comparison with sinking of mine workings allows exploring placer deposits of minerals with less expenditure of time and money. The main type of mechanized drilling of exploration wells in gold-bearing placers in the USSR and abroad is percussion-cable drilling.

When comparing the data of exploration and operation at the sites of the Sarbaisky and Sokolovskoye open pits, it was found that operational exploration on a grid of 50x25 m does little to refine the data of detailed exploration carried out on a grid of 100x50 m. At the same time, at the sites of both open pits, in detailed and operational exploration, ore reserves and the iron content in them are slightly underestimated.

A striking feature of the Devonian period is the widespread occurrence of reefs, most of which are associated with geosynclinal seas. In character and size, the Devonian reefs present a rather varied picture. The largest reefs are located in the marginal parts of geosynclinal troughs.

The territory of Pavlodar Priirtyshye is confined to the northeastern part of Eastern Kazakhstan. The Carboniferous and Permian deposits composing it are almost everywhere overlain by a cover of loose Mesozoic and Cenozoic sediments. Therefore, the geological survey and prospecting works carried out here, the purpose of which is to clarify the geological structure and to identify mineral resources, are associated with drilling.

The lithologic-paleophytologic substantiation of the subdivision of the Lower Permian coal-bearing deposits of the Minusinsk basin was made on the basis of a detailed lithologic-facies and paleophytologic description of the section at the Izyshskoye deposit, where the productive sequence (1750 m thick) is most fully developed and where sediments in the age range from the Carboniferous to the Permian are traced.

The role of concentrations of dispersed organic matter in the formation of its microcomponent composition was elucidated using 160 samples of insoluble organic matter concentrates obtained by enrichment from sediments of different ages and different regions of the Soviet Union.

Coal-bearing Paleogene and Neogene deposits in the area of the Dnieper-Donets depression are widely distributed. The lithologic and geologic features of the Paleogene-Neogene deposits of the Dnieper-Donets depression and the peculiarities of the structure of the Paleozoic basement are covered in great detail in the literature.

The stratigraphy of Carboniferous eugeosynclinal coal-bearing deposits of the eastern slope of the Urals, despite more than a century and a half of research, remains poorly studied. For most deposits, several stratigraphic schemes have been proposed, differently determining the age of the coal-bearing sequence — from Tournaisian to Visean and even Middle Carboniferous.

The question of the correct determination of the economic efficiency of geological exploration, despite its obvious importance and urgency, has not been finally resolved. In industrial practice, for this purpose the value of costs per unit of explored mineral reserves is used, i.e., the cost of exploration per unit of reserves. E. O. Pogrebitsky defines the economic efficiency of exploration work in percent as the ratio of the cost of exploration to the value of the extracted product...