Vol 61, No 4 (2019)

This paper successively reports on a methodology for investigating the orientation and morphogenetic characteristics of fault systems at four scale levels: kilometers, meters, centimeters, and millimeters. The research object is the Urtui granite massif in southeastern Transbaikalia west of the Streltsovska caldera, incorporating unique uranium deposits. The massif is composed of Late Riphean granites and granite gneisses variably affected by dynamometamorphic and hydrothermal–metasomatic alterations and is crosscut by numerous faults with traces of fluid activity from various tectogenesis episodes. The relationship between the geometric parameters of the fault systems, such as specific density and specific length, has been established. It is advisable to use these geostructural data for conceptual and numerical modeling of fluid filtration and radionuclide transport processes in the three-dimensional fractured–pore space of crystalline rocks, for reconstructing and modeling uranium ore formation, and using the geological space for the isolation of radioactive materials.

The article analyzes the regional gravitational field of northeastern China, Korea, and Western Primorye. The distribution of gold deposits is compared with the development of Mesozoic magmatism and negative gravitational field anomalies. Based on an analysis of geological, minerogenic, petrophysical, and geophysical materials, geological and geophysical zoning of the western part of the Khanka massif was carried out and a scheme was compiled for interpreting geological and geophysical data with minerogenic elements. The authors have determined the relationship between magnetic and gravitational field anomalies and the position of prospective gold-bearing ore districts and clusters in the junction zone of the North China Triassic–Jurassic volcanoplutonic belt with Proterozoic substrates of the Khanka massif. Based on geophysical data, early Jurassic intrusions were identified, which controlled the location of gold ore clusters. A conclusion is drawn about the relationship between gold mineralization and Jurassic magmatism, which increases the prospects for discovering gold mineralization in the Prikhankaysky region of Western Primorye.

Slepaya Zalezh’, the largest orebody of the Tyrnyauz Mo–W deposit, is considered a first-priority object should mining operations at the deposit be resumed. Molybdoscheelite, scheelite, and molybdenite impregnation in mineable concentrations is genetically related to metasomatites of the productive stage overprinted on skarns, periskarn rocks, hornfelses, and marble. Ore types have been recognized based on the relative amounts of different ore-bearing metasomatite facies and protoliths acting as a diluting mass. Seven ore types have been recognized and mapped in cross section. Types I and II are characterized by predominant (70–90%) aposkarn ores after endo- and exoskarns, accordingly. Type III is characterized by approximately equal proportions of ores after endoskarns and periskarn rocks; type IV differs from type III by a decrease in periskarn rocks replenished by an increase in hornfels. Type V is dominated by ores after exoskarns and, to a lower extent (up to 25%), after marble. Type VI is intermediate between types III and IV. Type VII represents all protoliths in approximately equal proportions. Each type exhibits a stable mineral and chemical composition inherited from the protolith. The ores of each particular type have simple distinguishing features, convenient for logging and mapping, which can be used for manual picking of grab and bulk samples and preliminary ore separation. The ores exhibit narrow ranges of variation in sizes and shapes of ore mineral grains and intergrowths and concentrations of minerals harmful to flotation. The subtle differences in ore mineral concentrations between ore types enable their selective mining and blending. Maps and cross sections contain data on the spatial distribution of the associated components such as garnet and wollastonite in skarns and productive metasomatites, pyroxene–plagioclase periskarn rocks, and hydrothermally altered rocks with Cu, Au, and other mineralization.