Vol 121

The state of the problem and approaches to forecasting of rare-metal mineralization are analyzed, the principles and methods of forecasting are discussed, it is shown that forecasting of endogenous, including rare-metal, deposits should be based on system analysis, modeling and geocybernetic (quantitative) approach.

The hypothesis of the existence of a connection between the distribution of chemical element contents by probability and in space is put forward. On the example of gold-quartz formation deposits the possibility of mathematical analysis of probability distributions and prediction on this basis of the nature of spatial variability (presence of nuggets) is shown. The prospects of application of similar methods in other sections of geology are discussed.

The principles of separation of non-kinematic structures and their peculiarities of primary importance for prediction are established. Genetically, the appearance of such structures is connected with the dilatancy environment of the regressive stage of metamorphism or with similar conditions existing in intrusive complexes at postmagmatic stages of their development. The basis of mineralogical evolution of focal structures is determined and the question of specificity of oreogenesis for the crystalline environment at dilatency and stretching is considered.

The structural and geometrical features of the location of eolotically silver ore bodies of vein type relative to ore-controlling and ore-bearing faults are considered. The scheme of local forecasting of hidden mineralization based on luminescent mapping of near-ore calcite-bearing metasomatites is proposed.

In the territory of the At-Uryakh-Shturmov zone there were three richest placers of Kolyma, now almost completely mined out. Native ore occurrences identified in the area of the zone are not comparable to the placers. Nevertheless, the regularities in the distribution of ore occurrences, established as a result of the conducted research, show that their number is far from being exhausted by the known ore occurrences, and, consequently, significant metal resources may be concentrated in them. However, in order to turn these resources into real reserves, it is necessary to take into account the laws outlined in the proposed article when prospecting and exploring these ore occurrences.

The geological structure and structure of the Zidarovskoye deposit are considered. Types of ores and near-ore metasomatites are described, their composition and sequence of mineral formation are characterized, concentric zonality of development within the deposit is revealed. Genetic connection of near-ore feldspatolites and propylites with copper-bismuth ores and berezites with gold-silver-polymetallic ores was established. Two gold-producing paragenesis were revealed: gold-chalcopyrite-sphalerite and gold-chalcopyrite-galenite; the latter is of industrial importance. The characteristic of morphology, size, composition and conditions of localization of nugget gold in ores is given. It is established that zonality of gold individuals reflects the regular change of its assay in gold-silver-polymetallic ores. Practical recommendations regarding prospectivity and local forecasting of gold mineralization of the deposit are made.

The question of the study of disjunctive parameters using fracture disjunctive determinants based on undirected core of exploration wells is considered. The author achieved maximum convergence of calculated and actual pictures and thus determined the disjunctive parameters. As a result, it was found out that the core fracturing data can only determine either the position, geological type, or shape of the fracture that caused the fracturing.

On the basis of studying the structure of tin ore veins the concept of "elementary fragment" (EF) of the vein is proposed.

The problem of predicting tin mineralization in the Bajalsk district from the point of view of ore-formation analysis is considered. The conclusion about the transitional character of mineralization is substantiated. The rational direction of development of criteria for prediction of mineralization, connected with the study of petrographic geochemical features of ores and metasomatites, is outlined.

In the conditions of prevailing structural-tectonic factor of control of mineralization the informative features for the selected facies of near-ore metasomatites of quartz-small-mica group are: average size of sericite or muscovite, pseudomorphic replacing biotite: degree of berezitization of grantoids, peculiarities of mineral composition of biotite neoplasms.

Four morphological types of outcrops on the surface of oxidized sulfide ores, caused by four types of processes of cryogenic and pre-cryogenic oxidation, are described. The main features of these processes that lead to changes in the contents of inert components (such as cassiterite) and in the thickness of vein ore bodies are described. The coefficients allowing to predict the values of parameters of unoxidized ore bodies on the basis of known parameters of the upper part of the oxidation zone are given.

The "transition zone" of the deposit is characterized and correlated with the horizon of disintegration and reduction processes of hypergenesis zones. Visual and mineralogical criteria for determining the boundaries of intervals characterized by reduced recoveries from tungsten trioxide ores were tested.

To predict the enrichment of ores at specific sites of stockevernous deposits for any stage of geological exploration, we propose criteria that can be ranked as follows: the main ones are the content of clay minerals in ores; the content of molybdates; the value and sign of molybdenite thermal EMF; the additional ones are the size and shape of molybdenite individuals, the character of the grain surface; the nature of aggregations with neighboring minerals and the openability of molybdenite.

In the basic and ultrabasic rocks of the Gulinsky massif of the Maymecha-Kotui province of the Kondersky massif of the Aldan province in the series of rocks: dunites - olivinites - peridotites - clinopyroxenites - gabbro, the content of rare earth elements increases, and the content of elements of the platinum group decreases. The content of noble metals in ultrabasic rocks correlates well with the content of rare earth elements and poorly with the content of other geochemical groups of elements.

The possibility of detecting crystal-controlling structures using the method of studying induced thermoluminescence of quartzites sampled from the surface or from drill hole cores was analyzed.

As a result of studying the morphology and optical properties of Iceland spar crystals on an ontogenetic basis, crystal morphological zonality, the relationship between the shape, internal structure and optical properties of the crystal and optical material were established. Identification of the regularity can be used for geological exploration process in the evaluation of prospects of objects and research works.

The following prospecting criteria are considered: 1) structural - confinement of manifestations to zones of large faults - fracture zones of northeastern strike; 2) magmatic - localization of Perelivt objects within granite complexes of the Murzinsko-Aluisky median massif; 3) metasomatic - halos of hydrothermal argillization of granites; 4) mineralogical - mineral composition of vein execution, order of combination of structures and textures of vein quartz, determined by ontogenic evolution of quartz-overflow vein substance. The formation of quartz-perelivt veins in this area is associated with the processes of tectonomagmatic activation in the early Mesozoic.