Geology and pyrite-polymetallic mineralization of the forecasted Limonite deposit, Rassokhinsky ore cluster (Yenisei ridge)

The development of Russia’s largest Gorevskoye leadzinc deposit (Gorevsky GOK, Novoangarsky OK) will depend on promising deposits of the Angara polymetallic ore region, in particular, those of the Rassokhinsky ore cluster. Based on the analysis of geological and geophysical information of previous and current studies, a major Limonite pyrite-polymetallic (massive sulfide) deposit is forecasted within it. The main lithological and stratigraphic criterion for the localization of ores is determined by their confinement to high-carbon black quartz-sericite schists of the upper subformation of the Potoskuy suite of the Upper Riphean. In the top of this pack, layered and massive pyrite-polymetallic ores, 70– 140 m thick, are localized. Based on PPA data, lead and zinc content in core varies from fractions of a percent to several percent, based on the ICP-AES method: 0,1– 3,7 % Pb, 0,1–6,4 % Zn, Pb : Zn ratio is 1 : (1–10).

Rare metal-polymetallic mineralization of Koshmansay ore field (Eastern Uzbekistan)

The Koshmansai ore field is located in the southern part of the granitoid Chatkal batholith, in its apical ledge and exocontact zones, in the Koshmansai river basin. The host environment of the granitoids is Lower Carboniferous carbonate rocks, which were primarily affected by intensive skarnification. Sedimentary-metamorphic and volcanics rocks and granitoids constitute the geological structure of the skarn rare-metal-polymetallic Koshmansai deposit. In the distribution of ore-forming and associated elе- ments in the mineral phases of skarn orebodies, their morphogenetic type plays a certain role. Thus, in bimetasomatic skarns, minerals accumulate more Cu, Zn, Ni, Te, Tl, Ge. In infiltration skarns, these are Ag, Pb, Bi, Cd, Sb, Co. Sulfide polymetallic mineralization in skarns is associated with quartz and calcite. The Koshmansai ore field has a distinct geochemical zoning, which can be subdivided into the Koshmansai rare- metal-polymetallic deposit at the upper levels of the ore field and the Nizhnekoshmansai rare-metal-copper ore occurrence at its lower levels. Nevertheless, orebodies formation proceeded in a similar thermodynamic environment, in the conditions of upper shielding at low temperature gradients, which makes it possible to consider the ore field as a single geochemical anomaly. The vertical geochemical zoning of ore-forming element halos determined by their concentration at the lower section levels of the Koshmansai deposit skarn orebodies suggests the expansion of its prospects in depth.

Polyformational Agdai Massif (Verkhoyansk-Kolyma Orogenic Region)

The earliest Mesozoic granitoid formations of the Verkhoyansk-Kolyma orogenic region are derivatives of the Late Jurassic-Early Cretaceous gabbro-diorite-granodiorite formation, involvinggold and polymetallic mineralization. Late Cretaceous alkaline-feldspar or alkaline granites with associated rare-earth mineralization complete the granitoid magmatism of the region. The Agdai massif, which combines both of the mentioned groups of rocks, was the object of our research. Therefore, understanding their petrological and genetic features is of great interest. It is determined that the eastern part of the massif is composed of diorites and granodiorites and includes autoliths and xenoliths of gabbro-diorite composition. The isotopic K-Ar age of gabbro-diorites is 154Ma, diorites –148 Ma, granodiorites –117–124 Ma, and dike granites – 114 Ma. The rocks are characterized bydisequilibrium mineral assemblages: early magmatic pyroxene-Labrador, typical for the basic rocks, and late - micropegmatite granitoid. The origin of the parent melts occurred within the lower crust in amphibolite substrates at temperatures of 1000–1150°C and a pressure of 1.4-1.6 GPa under the influence of the mantle main melt and the partial mixing of the latter with the resulting crustal melt. The western part of the outcrop was formed at the beginning of the Late Cretaceous (the isotopic K-Ar age of the granites is 92+/-3 Ma) and is composed of alkaline feldspar leucogranites. According to all petro - and geochemical parameters, the rocks are defined as post-orogenic or rift-related granites of the A-type. The presence of inclusions of pyroxene-labrador composition, titanomagnetite, zircon of morphotype D and the ratio of the basic petrochemical parameters allow us to refer them to A-type granites related to continental rifting. High melt temperatures (990-1030°C) at relatively low pressures during magma generation (0.7–0.8 GPa) could be achieved only when additional heat was supplied from an external (deep) source. The presence of nonequilibrium mineral associations indicates a possible syntax of the granite and the main melt. In general, the Agdai massif is a polyformational, polygenic structure formed by the intrusion of melts through common or closely located magma conduits.

Conditions of localization and patterns of distribution of gold-poly-metal mineralization of the Dagkesaman deposits (Lesser Caucasus, Azerbaijan)

We studied the structural-morphological types and mineral composition of ore bodies, stages of ore development and conditions of development of the deposits. The research revealed significant elements of the corresponding conditions of localization of gold-polymetallic mineralization, the most characteristic being albitophyre subvolcanic bodies and steeply-dipping damages related to them. According to the structural-morphologic peculiarities, the ore bodies should be united under three categories: 1) simple vein; 2) complex vein; 3) veinlet-impregnation types. The positions of gold ore bodies and their morphological peculiarities were found to be determined by structural factors. Presence of small ruptures, differently-oriented systems of fractures and faults, which run across the area, gentle curves of these systems and other structural elements –all of this promotes gold ore development. There research determined aureoles of ore-containing altered rocks (serialization, chloritization, kaolization and calcinations, and limonitization from hypergenical zones) and presence of zonal structure. Gold-productive areas were identified as the quartz-pyrite association with disperse gold, and especially, the second mineral association where there is a notable close paragenetic connection between noticeable gold and chalcopyrite-galena parageneis of polymetallic stage. In the process of ore development, the physical-chemical conditions have presumably changed from average deep (quartz-pyrite-sericite) to shallow (quartz-galena- sphalerite-gold ore) and close-to-the-surface (quartz-chalcocite-hematite). Gold that occurs with all the mentioned minerals of this stage has developed in the temperature interval of 220–160 °C. The study found the ores to be complex, containing the following dditional elements: Fe, Cu, S, Bi, Zn, Pb, As, Se, Te. The main fossil component is gold. Industrially valuable are also cadmium, zink, copper and silver, found in the ores. We found the following morphological types of grains of native gold: homogenous, zonal, mono-granular, spotted, which are of great significance for concluding on genesis of the deposits, prognoses, explorations and assessments.

Application of multivariate canonical harmonic trend analysis, singularity analysis with radius-areal metal amount and improved adaptive fuzzy self-organizing mapping to identify geochemical anomaly related to iron polymetallic mineralization in Hunjiang district, Northeastern China

How to more effectively perform anomaly detection of combination information has always been an important issue for the scholars in various fields. In order to identify and extract the geochemical anomaly information related to polymetallic mineralization in the Hunjiang area, this article uses the hybrid method that combines multivariate canonical harmonic trend analysis (MCHTA), singularity analysis with radius-areal metal amount and improved adaptive fuzzy self-organizing map (IAFSOM). First, multiple sets of combination feature information with multi-dimensional variables will be obtained through the MCHTA method, which information is considered as the initial information for the subsequent analysis. Next, the singularity analysis method is used to process the combination concentration value to calculate the singularity indexes. Finally, the singularity indexes are classified by the IAFSOM method, and nine groups of sample data are obtained. The analysis results found that the samples information in fourth group covered most of the low α-values. The main conclusions in this study are as follows: (1) The MCHTA method can effectively detect the combination information related to geochemical anomaly; (2) The application of singularity analysis method with radius-areal metal amount can reveal the significant characteristics of mineralization combination elements; (3) IAFSOM can be used as an effective tool for the classification and identification of geochemical anomaly with combination information; (4) the hybrid method that combines MCHTA method, singularity analysis and IAFSOM model has a good indication significance in the prospecting of geochemical anomalies, and could provide a good method for geochemical prospecting.