Ore Region Research Articles

Investigation of general regression neural network architecture for grade estimation of an Indian iron ore deposit

The mineral resource estimation requires accurate prediction of the grade at location from limited borehole information. It plays the dominant role in the decision-making process for investment and development of various mining projects and hence become an important and crucial stage. This paper evaluvates the use of two distinct artificial neural network (ANN)-based models, general regression neural network (GRNN) and multilayer perceptron neural network (MLP NN), to improve the grade estimation from Koira iron ore region in Sundargarh district, Odisha. ANN-based models capture the inherent complex structure of mineral deposits and provide a reliable generalization of the iron grade. The ANN-based approach does not require any preliminary geological study and is free from any statistical assumption on the raw data before its application. The GRNN is a one-pass learning algorithm and does not require any iterative procedure for training less complex structure and requires only one learning parameter for optimization. In this investigation, the spatial coordinates and multiple lithological units were taken as input variables and the iron grade was taken as the output variable. The comparative analysis of these models has been carried out and the results obtained were validated with traditional geostatistical method ordinary kriging (OK). The GRNN model outperforms the other methods, i.e. MLP and OK, with respect to generalization and predictability of the grades at an un-sampled location.

Ulfanderssonite-(Ce), a new Cl-bearing REE silicate mineral species from the Malmkärra mine, Norberg, Sweden

Ulfanderssonite-(Ce) is a new mineral (IMA 2016-107) from the long-abandoned Malmkarra iron mine, one of the Bastnas-type Fe-rare earth element ( REE ) deposits in the Bergslagen ore region, central Sweden. It is named for Ulf B. Andersson, a Swedish geologist and petrologist. In the type specimen, the mineral occurs with vastmanlandite-(Ce), bastnasite-(Ce), phlogopite, talc, magnetite, pyrite, fluorbritholite-(Ce) and scheelite. Ulfanderssonite-(Ce) forms pinkish, translucent subhedral grains, 100–300 μm, in aggregates up to 2 mm. Fracture is uneven, and there is an indistinct cleavage parallel (001). Mohs’ hardness is 5–6, D calc = 4.97 g cm −3 . Optically, ulfanderssonite-(Ce) is nonpleochroic, biaxial negative, with 2 V meas = 55° and n calc = 1.82. The ideal composition is Ce 15 CaMg 2 (SiO 4 ) 10 (SiO 3 OH)(OH,F) 5 Cl 3 . Electron microprobe and LA-ICP-MS chemical analyses yielded (in wt%) La 2 O 3 11.87, Ce 2 O 3 30.98, Pr 2 O 3 3.99, Nd 2 O 3 17.14, Sm 2 O 3 2.81, Eu 2 O 3 0.18, Gd 2 O 3 1.15, Dy 2 O 3 0.30, Tb 2 O 3 0.10, Y 2 O 3 1.11, CaO 2.26, FeO 0.02, MgO 1.97, P 2 O 5 0.08, SiO 2 19.13, H 2 O calc 1.07, F 1.09, Cl 2.89, O=(F, Cl) −1.10, sum 97.04. The five strongest powder X-ray diffraction lines are [ I (%) d obs (A) ( hkl )]: 100 2.948 (−421), 47 2.923 (204), 32 2.660(−225), 26 3.524 (40-1), 25 1.7601 (6-23). Ulfanderssonite-(Ce) is monoclinic, Cm , with a = 14.1403(8), b = 10.7430(7), c = 15.498(1) A, β = 106.615(6)° and V = 2256.0(2) A 3 for Z = 2. The crystal structure has been solved by direct methods and refined to R 1 = 2.97% for 5280 observed reflections. It consists of a regular alternation of two layers, designated A and B , along the c -axis: A ( ca . 9 A thickness), with composition [(Ce 8 Ca), MgSi 7 O 22 (OH,F) 4 ] 8+ , and B ( ca . 6.5 A with composition [Ce 7 MgSi 4 O 21 (OH,F) 2 Cl 3 ] 8− ; the A layer is topologically and chemically closely related to cerite-(Ce). A FTIR spectrum shows strong absorption in the region 2850–3650 cm −1 , related to the presence of O–H stretching bands. Ulfanderssonite-(Ce) is interpreted as a primary mineral at the deposit, along with the more common fluorbritholite-(Ce), formed by a magmatic-hydrothermal fluid with REE, Si, F and Cl ion complexes reacting with dolomite marble. The presence of ulfanderssonite-(Ce) is direct evidence of a Cl-rich mineral-forming aqueous solution, normally not reflected in the composition of skarn minerals in Bastnas-type deposits.

ORE SYSTEMS: TYPES, AND GEODYNAMIC SETTINGS FOR THEIR OCCURRENCE (EASTERN SIBERIA)

The Mineralogy, Petrography and Minerals Department of the Irkutsk State Technical University (now the Irkutsk National Research Technical University) has been studying the structural, mineralogical and geochemical features of ore fields for over 30 years. We investigated more than 25 deposits of gold, uranium, rare, non-ferrous and ferrous metals, and published the prognostic metallogenic maps of the ore regions located in Eastern Siberia, Mongolia and Yakutia. Our experience shows that knowing only the genetic characteristics of ore objects is not sufficient for proper metallogenic studies. A complete set of deposit characteristics should include the data on structure, composition, localization conditions and other properties of ore objects and fields. We propose to introduce the “ore system” (OS) concept considering a combination of genetically (paragenetically) related and interrelated petrological, tectonic, metamorphic, mineralogical, geochemical and lithological elements formed during the pre-ore (preparatory) and ore-formation stages [Seminsky, 1990]. In contrast to the proposed OS concept, common terms, such as “ore-magmatic”, “oremetasomatic”, “ore-generating”, “ore-localizing” systems, usually consider only one aspect of the ore process or object [Russian Metallogenic Dictionary, 2003]. In our opinion, descriptions and typification of ore objects viewed as OS should refer to two groups of characteristics.

Mineralogical and geochemical features of magnesia-ferruginous carbonates of the Avzyan ore region of the Southern Ural in connection with metasomathosis regularities

Mineralogical and geochemical features of magnesia-ferruginous carbonates of the Avzyan ore region of the Southern Ural in connection with metasomathosis regularities

Investigation of fractal properties of the magnetic survey data array in the Pechenga ore region using two-dimensional wavelet analysis

The article deals with a study of the fractal properties of geophysical data arrays obtained by areal geophysical works over hierarchically organized geologic systems. It was shown by the example of magnetic survey data in the Pechenga ore region that two-dimensional wavelet analysis is a useful tool for investigating the fractal properties of geophysical data arrays. The application of wavelet analysis allows detecting the hierarchical structure of organization of the whole ore region, estimating the degree of the system inhomogeneity, and concluding about local properties of a geologic system, for example, the ore potential of separate sites.

Indium mineralisation in SW England: Host parageneses and mineralogical relations

The SW England ore region contains significant amounts of indium (In) in Early Permian granite-related skarn and lode parageneses and, to a lesser extent, Triassic epithermal “crosscourse” veins. Ore parageneses that predate granite emplacement (Devonian and Lower Carboniferous sedimentary exhalative and vein parageneses) are largely devoid of In. Cadmium (Cd) and gallium (Ga) occur widely in all sulphide-bearing parageneses across the region with sphalerite concentrations locally reaching 1.74wt% Cd and 1750ppmGa.Indium displays a strong affinity to sulphide-bearing magmatic-hydrothermal parageneses. It occurs in silicate-sulphide skarns, polymetallic sulphide lodes and sulphide-bearing portions of greisen-bordered sheeted vein systems and quartz-tourmaline lodes across the region. Magnetite-silicate skarns and quartz-tourmaline lodes that are devoid of sulphide, in contrast, were comparatively unfavourable for In precipitation. The highest In concentrations are found in mineral lodes associated with the Carnmenellis and St Agnes granites, which are the districts that had the highest historical production of Sn. Total In concentrations in these areas locally exceed 430ppm, while concentrations elsewhere are systematically below 200ppm.The principal In hosts are chalcopyrite, sphalerite and stannite group minerals with local concentrations within cassiterite and tennantite. Surprisingly, chalcopyrite accounts for the majority of the In budget throughout the region, although concentrations are highest in sphalerite and stannite group minerals. Sphalerite locally contains up to 1.42wt% In, chalcopyrite has up to 2200ppm and stannite group minerals up to 6800ppm. No In was detected in löllingite, arsenopyrite, rutile, haematite, magnetite, tourmaline, biotite, chlorite, galena, bornite, chalcocite or pyrrhotite. Scattered concentrations in pyrite relate to impurities rather than incorporation by solid solution. Roquesite and possibly dzhalindite or native In formed locally where In-bearing chalcopyrite or sphalerite has been replaced by bornite and quartz. The In partitioning between sphalerite and chalcopyrite varies broadly between 1:1 and 10:1.Sporadic In was included in Triassic crosscourse veins as a result of interactions between migrating CaCl2-rich basinal brines and earlier formed granite-related parageneses. The interactions involved at least two distinct components: 1) Incorporation of clasts of magmatic-hydrothermal veins in crosscourse veins during faulting, and 2) Dissolution and re-precipitation of magmatic-hydrothermal vein minerals in crosscourse fluids. Local concentrations reach 140ppm In.The magmatic-hydrothermal parageneses in SW England are comparable to the South China Tin Belt, Mount Pleasant, as well as Erzgebirge/Krušné Hory. Magmatic-hydrothermal fluids associated with peraluminous granites have developed a variety of skarn, greisen, lode and veins parageneses by interactions with their host rocks and contained fluids. Crosscourse epithermal mineralisation occurred as In was transported by CaCl2-rich basinal brines in a similar manner as In-bearing veins in the West Shropshire ore field.

Aerogravity and remote sensing observations of an iron deposit in Gara Djebilet, southwestern Algeria

The Gara Djebilet iron ore region is one of the most important regions in Africa. Located in the southwestern part of Algeria at the border with Mauritania, the Gara Djebilet region is characterized by steep terrain, which makes this area not easily accessible. Due to these conditions, remote sensing techniques and geophysics are the best ways to map this iron ore. The Gara Djebilet formations are characterized by high iron content that is especially rich in hematite, chamosite and goethite. The high iron content causes an absorption band at 0.88 μm, which is referred to as band 5 in the Operational Land Imager (OLI) Landsat 8 images. In this study, we integrated geological data, aerogravity data, and remote sensing data for the purpose of mapping the distribution of the Gara Djebilet iron deposit.Several remote sensing treatments were applied to the Landsat 8 OLI image, such as color composites, band ratioing, principal component analysis and a mathematical index, which helped locate the surface distribution of the iron ore. The results from gravity gradient interpretation techniques, 2-D forward modeling and 3-D inversion of aerogravity data provided information about the 2-D and 3-D distribution of the iron deposit. The combination of remote sensing and gravity results help us evaluate the ore potential of Gara Djebilet. The estimated tonnage of the iron ore at Gara Djebilet is approximately 2.37 billion tonnes with 57% Fe.

ALKALINE VEIN ROCKS OF THE KARA ORE NODE: THE COMPOSITION OF ORE-FORMING SOLUTIONS AND CONDITIONS OF THEIR FORMATION (BASED ON THE STUDY OF FLUID INCLUSIONS)

The Kara ore node is located within the Sretensk-Kara ore region of East Transbaikalia. The geological structure of this area is complex due to its location within the Mongol-Okhotsk suture, the zone wherein the Siberian and Mongolia-China continents collided into each other at the turn of the Early and Middle Jurassic. During the plate collision, intense magmatism was accompanied by the formation of focal-dome, dome-ring and other structures. The Kara ore node is controlled by the Ust-Kara focal dome-ring structure. The central part of latter is composed of Kara-Chacha granitoids from the Amudzhikan-Sretensk intrusive complex (J 3 -K 1 ) with the system of subvolcanic and vein formations, including grorudites. It is suggested that gold mineralization in the study area is genetically related to grorudites; however, physical and chemical conditions for the formation of these alkaline rocks, their genesis and role in the hydrothermal gold-ore process still have not been sufficiently investigated. To this end, the authors of this paper have studied fluid inclusions (FI) in quartz from these rocks. It has been found that quartz porphyry phenocrysts in grorudite contain FI of diverse forms, the size of which ranges from 5 to 48 microns. Measured temperatures of ice melting (–2.5°C) and complete homogenization into liquid (350 °C) show that the concentration of salts in the fluid amounts to 4.2 wt % of eq. NaC, its density is 0.64 g/cm 3 , and the pressure is 1.6 kb. At LA-ICP-MS of individual FI, clear analytical signals were derived from Na and K. As, Mo, Sb, Cs, W, and Hg were traced in significant quantities. The Raman scanning showed the presence of N 2 in the primary (substantially gaseous) FI, and CO 2 , N 2 , and CH 4 in the primary-secondary FI.

Thermodynamic modeling of the behavior of Uranium and Arsenic in mineralized Shaazgai-Nuur Lake (Northwest Mongolia)

Highly mineralized closed lakes on the territory of ore regions of Mongolia are of special interest in relation to the search for nonconventional sources of metals. Water of soda Shaazgai-Nuur Lake contains ~1 mg/L U, and the content of the undesirable admixture of As is up to 300 μg/L. Uranium and Arsenic speciation in solution and in the bottom sediments of the lake was estimated using thermodynamic modeling, and a method of their separation was suggested. Calculation of the models of sorption of these elements by goethite and calcite showed that at pH 9.4 typical of natural water it could be effective only at a high concentration of FeOOH sorbent. In this case, at pH 8 (the area of U sorption), As may be removed by simple filtering of solutions from the suspension upon additional coagulation.

New zircon U-Pb dating of the Bohutín Stock in the Příbram Ore Region, Czech Republic

New zircon U-Pb dating of the Bohutín Stock in the Příbram Ore Region, Czech Republic

SIRT1 contributes to aldose reductase expression through modulating NFAT5 under osmotic stress: In vitro and in silico insights

So far, a myriad of molecules were characterized to modulate NFAT5 and its downstream targets. Among these NFAT5 modifiers, SIRT1 was proposed to have a promising role in NFAT5 dependent events, yet the exact underlying mechanism still remains obscure. Hence, the link between SIRT1 and NFAT5-aldose reductase (AR) axis under osmotic stress, was aimed to be delineated in this study. A unique osmotic stress model was generated and its mechanistic components were deciphered in U937 monocytes. In this model, AR expression and nuclear NFAT5 stabilization were revealed to be positively regulated by SIRT1 through utilization of pharmacological modulators. Overexpression and co-transfection studies of NFAT5 and SIRT1 further validated the contribution of SIRT1 to AR and NFAT5. The involvement of SIRT1 activity in these events was mediated via modification of DNA binding of NFAT5 to AR ORE region. Besides, NFAT5 and SIRT1 were also shown to co-immunoprecipitate under isosmotic conditions and this interaction was disrupted by osmotic stress. Further in silico experiments were conducted to investigate if SIRT1 directly targets NFAT5. In this regard, certain lysine residues of NFAT5, when kept deacetylated, were found to contribute to its DNA binding and SIRT1 was shown to directly bind K282 of NFAT5. Based on these in vitro and in silico findings, SIRT1 was identified, for the first time, as a novel positive regulator of NFAT5 dependent AR expression under osmotic stress in U937 monocytes.

AN EXPERIMENTAL EVALUATION OF TINNY ROCKS POSTORE CUT-OFF

A complex approach to tin-deposit valuation is shown with Badjal ore region (Khabarovsk district) as an example. The approach is based on the estimation of the post-mineralization cut-off by morphostructural analysis and crystallographic methods. The using of both methods aids to obtain more detailed and valid assessment: morphostructural analysis gives the pattern of certain blocks or sites; crystallographic one gives the value of the ore-deposit cut-off. This approach helps to allocate the most promising sites.

Assessing the competitiveness of the supply side response to China's iron ore demand shock

This article examines the scale of China's demand shock and the supply-side reaction in established and fringe iron ore regions. It outlines the short-run constraints on supply expansion and explores the supply-side response to understand whether the long-run iron ore market adjustment has been competitive, or influenced by strategic supply and price interventions by incumbent producers.

Application of the radio holographic method in the prospecting for local ore bodies

Application of the radio holographic method for prospecting for the local ore bodies is considered by the example of the Loipishnyun area of the Monchegorsk ore region. The radio holographic method is a very fast and efficient instrument for visualizing the geoelectrical heterogeneities in the Earth’s crust. Based on the surface array measurements of the amplitude and phase electromagnetic responses, the holographic reconstruction of the medium locates anomalous areas with high electric conductivity.

Study on the Soil Enzyme Activities of High Phosphorus Region in Xiangxi River Watershed

The rich phosphorus resources in Xiangxi river watershed had a serious impact on water quality of Xiangxi River. The phosphate ore region distributed in this area was selected as studying area, and the activities of different soil enzymes in 0-20cm and 20-40cm soil layers in mining zone (MZ), transportation zone (TZ) and hydro-fluctuation zone (HFZ) were respectively measured. Meanwhile, the differences of enzymes in the two soil layers between different regions were analyzed. The main results were as follows: The activity of soil polyphenol oxidase decreased in the order of MZ> TZ > HFZ, while the activities of soil catalase, sucrase, urease and alkaline phosphatase were higher in TZ and lower in MZ; Except the activity of soil invertase, the activities of other enzymes in 20-40 cm soil layer were mainly higher than those in 0-20 cm soil layer; The activities of soil enzymes in different regions of XXR watershed had significant differences with each other and were mainly correlated with soil pH, OM and TN; Soil enzymes such as catalase, polyphenol oxidase, invertase, urease and alkaline phosphatase are sensitive to the environmental conditions around the soil, and they could be used as effective indicators reflecting the soil quality in mineral regions.

238U/235U isotope ratio variations in minerals from hydrothermal uranium deposits

The 238U/235U ratio was precisely measured in uranium minerals from 11 hydrothermal deposits of different geologic settings and ages situated in ore regions of Asia, Europe, Africa, and North America by MC-ICP-MS using a 233U-236U double spike. The spike was calibrated in reference to the CRM-112A standard with 238U/235U = 137.837 ± 0.015 (Richter et al, 2010). The long-term reproducibility of 238U/235U measurement was estimated as ±0.07‰ by the analysis of monitor samples and the IRMM-3184 standard. The analyses were performed using 0.02–0.04-mg microsamples of uraninite, pitchblende, and coffinite, which were locally extracted from polished sections under an optical microscope. The 238U/235U values obtained for 50 samples of U-bearing minerals range from 137.703 to 137.821, with a 0.86‰ difference and a mean 238U/235U value of 137.773 ± 0.056 (±2SD). The range of 238U/235U variations in seven deposits with uraninite is 0.41‰, which is twice as low as for the deposits with pitchblende-dominated ores. Our study provided the first results for 238U/235U variations in minerals from individual deposits. The largest variations were found in the Oktyabr’skii (Eastern Transbaikalia), Schlema-Alberoda (Erzgebirge), and Shea Creek (Athabasca basin) deposits: 0.70, 0.33, and 0.59‰, respectively. Uranium from the early growth zones of 4–5 mm thick pitchblende spherulitic crusts is isotopically heavier (by 0.22–0.45‰) than uranium from the latest growth zones. A similar isotopic shift in 238U/235U in terms of magnitude (0.31‰) and sense was observed between pitchblende and coffinite overgrowths. The uranium isotopic composition of late pitchblende generations, the products of dissolution and reprecipitation of early phases, is 0.46‰ lighter than that of early pitchblende phases. The character of uranium isotope distribution in pitchblende aggregates is consistent with nuclear-volume-dependent isotope fractionation accompanying U(VI) reduction to U(IV) (Bigeleisen, 1996; Schauble, 2007; Stirling et al., 2007), which causes an enrichment of the U(IV)-bearing solid phase in the heavy isotope 238U. The range of 238U/235U ratios for 11 hydrothermal (high-temperature) deposits (137.703–137.821) lies well within the broader (two-fold) range of values determined for the low-temperature deposits Dybryn in Transbaikalia (Golubev et al., 2013) and Pepegoona in South Australia (Murphy et al., 2014). This can be explained by the fact that the uranium isotopic fractionation associating with U(VI) → U(IV) reduction is accompanied by isotope shifts owing to the long-term interaction of groundwater with early phases within sandstone-type deposits. At the same time, owing to the higher temperatures (by 100–300°C) of formation of hydrothermal deposits compared with sandstone-type deposits, nuclear-volume-dependent uranium isotope fractionation decreases by more than a factor of 2 (Bopp et al., 2009).

Sewage sludge and fly ash mixture as an alternative for decontaminating lead and zinc ore regions.

Many years of heavy industrial processes in the Upper Silesian Industrial Region in Poland (ore flotation, metal smelting and battery scrap processing) have resulted in lead, zinc and cadmium pollution of the air and soil. The most significant issues stem not only from elevated levels of these metals in environmental compartments, but also from the uneven pattern of their distribution. Point sources of local metal concentration are to be found dispersed over areas of contaminated soil. Such distribution is a challenge for remediation technology, as it precludes the introduction of standard procedures. Metals present in the soil pose a constant risk for living organisms. One of the most effective ways of limiting their ecological impact is by decreasing their mobility. In this study, the effect of introducing sewage sludge and fly ash mixtures (sluash material) into contaminated soil was evaluated. We tested the mixture in terms of the probability of its ecotoxicological impact on plant growth and development. The data obtained have shown that even low doses (3%) of sluash are effective in reducing the bioavailability of lead, cadmium and zinc, resulting in a decrease of their concentration in plants. The application of sluash also led to stabilize soil pH. It also had a positive impact on the total number of soil bacteria and soil fungi.

Characterization of Heavy Metals in a Uranium Ore Region of the State of Pernambuco, Brazil

The concentrations of As, Zn, Co, Cr, and Ba were determined in soil samples from an anomalous uranium ore region in the countryside of the state of Pernambuco, Brazil. The main land use system in this region is dairy farming, and there is a need to evaluate the potential risk of milk contamination. Twenty-three soil samples were activated with neutrons and analyzed using a high-resolution gamma-ray spectrometer system. The results, recorded in mg kg(-1), varied from 0.4 to 6.7 for As, from 17.0 to 110.0 for Zn, from 2.8 to 38.4 for Co, from 12.1 to 65.5 for Cr, and from 443.0 to 1,497.0 for Ba. All of the Ba concentrations were higher than the intervention value adopted by the Brazilian National Environmental Board. This finding justifies research in other environmental areas to predict the toxicological risks to the local population.

10.5937/mmeb1402001m = Preliminary geological exploration works in order to the environmental management in the area of inactive ecological mining field

Bor is otherwise a typical mining town, founded by the mine. Continued economic activity in the dominant area of extractive industry, related to the copper ore mining and processing, then for metallurgy and complementary industrial activities, what is of great importance for the town and the municipality. The northern part of the Timok magmatic complex and the Bor metallogenic zone, or the Bor mining region, covers the area in which the most significant ore fields are Bor, Veliki Krivelj Cerovo, Majdanpek, Blagojev Kamen and others. The largest technogenic formations were separated in the immediate vicinity of the Bor and Krivelj mine, and they are presented by formations originated by exploitation of mineral copper deposits (overburden) and mineral processing (flotation tailing dumps) in the immediate vicinity of Bor. Designed exploration works in the area of environmental inactive mining field were aimed to prepare the conditions for environment management, remediation of tailing dumps and landfills for disposal of mining waste in the Bor mining areas as well as the rehabilitation of ecological problems in the ore region of Bor. Exploration works included the study of the field: for disposal the tailings from Veliki Krivelj area of the Old Bor Tailing Dump (East), Saraka overburden dump, south-eastern overburden dump and RTH.

Deposits of minerals of the Kirovograd ore region of the Ukrainian shield: connection with the deep process

Conditions of magmatic rocks complexes and mineral deposits formation of the central part of the Ingul block are determined by existence of two melting sources in the mantle and the crust as well as by the deep permeable «transform» zone - tectonic suture Kherson-Smolensk. Along the deep transform zone supply of the mantle source by melts and fluids is realized and the existence of the crust source provides mixing of earlier melts with new portions added from the mantle. Changing of composition of the deep fluid as well as its transformation in the melts of both sources of melting causes the composition of deposits produced near the surface. Production of quarts gold ore veins is related to water chloride-potassium fluids accompanying formation of palingenetic Kirovograd granites. Increase of fluid alkalinity in the mantle source predetermines activity of the elements which are able to be brought to melt in alkaline environment - titanium and uranium. Gradual dilution of residual crust melts with fluoride-sodium fluid leads to appearance of lithium pegmatite with rare metal mineralization. Accumulation of Li, С s, Ве , Nb et al. is related to changing of distribution coefficients between solid phases and granite melt in presence of fluorine. During the process of Korsun-Novomirgorod pluton and albitite formation, alkalinity of deep fluid increases. In the crustal source its dilution by water takes place that leads to decrease of alkalinity and increase of oxidation potential. Deposition of brannerite and uranium oxides becomes possible.