Factor analysis of the geochemical associations in the Plavica ore deposit, Republic of North Macedonia

The aim of this study is to investigate the geochemical associations in the Plavica deposit in Republic of North Macedonia. The analyses of drill core samples from the detail exploration works were statistically processed to determine the groups of chemical elements with common spatial distributions. The resulting geochemical groups represent different stages of the ore forming hydrothermal processes. The main ore elements are represented by geochemical association of ([As, Sb, Au, Sn] Cu, Bi, Fe, Ag) which group outlines the ore bodies.

Tellurium and Selenium Mineralogy of Gold Deposits in Northern Fennoscandia

Mineralization of Te and Se was found in gold deposits and uranium occurrences, located in the Paleoproterozoic greenstone belts in Northern Fennoscandia. These deposits are of different genesis, but all of them formed at the late stages of the Svecofennian orogeny, and they have common geochemical association of metals Au, Cu, Co, U, Bi, Te, and Se. The prevalentTe minerals are Ni and Fe tellurides melonite and frohbergite, and Pb telluride altaite. Bismuth tellurides were detected in many deposits in the region, but usually not more than in two–three grains. The main selenide in the studied deposits is clausthalite. The most diversified selenium mineralization (clausthalite, klockmannite, kawazulite, skippenite, poubaite) was discovered in the deposits, located in the Russian part of the Salla-Kuolajarvi belt. Consecutive change of sulfides by tellurides, then by selenotellurides and later by selenides, indicates increase of selenium fugacity, fSe2, in relation to fTe2 and to fS2in the mineralizing fluids. Gold-, selenium-, and tellutium-rich fluids are potentially linked with the post-Svecofennian thermal event and intrusion of post-orogenic granites (1.79–1.75 Ga) in the Salla-Kuolajarvi and Perapohja belts. Study of fluid inclusions in quartz from the deposits in the Salla-Kuolajarvi belt showed that the fluids were high-temperature (240–>300 °C) with high salinity (up to 26% NaCl-eq.). Composition of all studied selenotellurides, kawazulite-skippenite, and poubaite varies significantly in Se/Te ratio and in Pb content. Skippenite and kawazulite show the full range of Se-Te isomorphism. Ni-Co and Co-Fe substitution plays an important role in melonite and mattagamite: high cobalt was detected in nickel telluride in the Juomasuo and Konttiaho, and mattagamites from Ozernoe and Juomasuo contain significant Fe.In the Ozernoe uranium occurrence, the main mineral-concentrator of selenium is molybdenite, which contains up to 16 wt.% of Se in the marginal parts of the grains. The molybdenite is rich in Re (up to 1.2 wt.%), and the impurity of Re is irregularly distributed in molybdenite flakes and spherulites.

DISTRIBUTION OF MERCURY IN COAL SEAMS (ON THE EXAMPLE OF THE KRASNOARMEISKIY GEOLOGICAL AND INDUSTRIAL REGION OF DONBASS)

Purpose. Analysis of the distribution of mercury concentrations in the whole district; identification of links between mercury content and other toxic and potentially toxic elements, petrographic composition of coal and its main technological parameters. Methodology. The methods of mathematical statistics with the construction of histograms of distribution and dendrograms of clustering of coal seams of the region by Hg concentrations are also used in the work. Results. Peculiarities of distribution and the nature of mercury distribution in 56 coal seams, which belong to the suites С14, С21, С22, С23, С25, С26, and С27 of the lower and middle divisions of the coal period of the Krasnoarmeysk geologicalindustrial area, have been determined. Simple and cumulative histograms are constructed and analyzed. The calculations of the weighted average concentrations in the coal of the main layers and suites were performed, the composition of the typomorphic geochemical association of mercury with other toxic and potentially toxic elements in the coal of the region is clarified. The main factors influencing the mercury content in the nearest stratigraphic section of coal seams in the process of coal accumulation and epigenetic transformations of the coal seam were significantly varied. The average value of mercury content in coal of the main working seams of the area is significantly below the maximum allowable concentration in coal. In the district as a whole, there is no significant connection between mercury concentrations and ash content and sulfur content of total coal, at the same time there is an increase in mercury content with increasing degree of coal carbonization. Scientific novelty. The nature of the distribution and the main statistical indicators of mercury concentrations in the main coal seams and suites of the Krasnoarmeysky geological-industrial region of Donbass were established. A typomorphic geochemical association of mercury with other toxic and potentially toxic elements in the coal seams of the district has been established. Practical significance. The practical significance of the obtained results is to identify the absence of a significant relationship between mercury concentrations and ash content and sulfur content of total coal, as well as to calculate the regression equations between the elements included in the geochemical association with mercury. Key words: mercury, mine, coal height, coal ash content, depth, sulfur content, regression equation, correlation coefficient.

Biogeochemical characteristics of parks and public gardens in Rostov-on-Don

The distribution of heavy metals and arsenic in the soils and leaves of the locust in the parks and squares of Rostov-on-Don was studied. 81 samples of soil and 30 samples of leaves were selected in 13 parks of the city. To determine the concentrations of elements, we used the approximate-quantitative and atomic-absorption analyses. For all elements, the concentration coefficient was calculated, as well as the hazard factor representing the multiplicity of exceeding the MAC or AAC. The total pollution index (Zc), which is the sum of the excess concentrations of individual elements above the background level, was used to characterize complex pollution. When comparing the average concentrations of metals and arsenic with the natural pedogeochemical background, a geochemical association is revealed: Cu2,5Zn2,3Pb1,8V1,3Hg1,3Ni1,2Cd1,2, typical of Rostov-on-Don soils. Weakly local pollution of soils of parks and squares with zinc, copper, vanadium and lead was revealed. The most common pollutant is zinc, for which the highest excess of AAC is characteristic. Pollution of the soil cover of recreational areas is assessed as permissible. With the passage of time, the concentration of zinc decreases and the concentrations of copper and vanadium increase in the soils of park landscapes. There has been increasing biological absorption by the leaves of the locust copper and molybdenum.

Mineralogical and Geochemical Characterization of Gold Bearing Quartz Veins and Soils in Parts of Maru Schist Belt Area, Northwestern Nigeria

Epigenetic, N-S, NNE-SSW quartz veins crosscut metapelites and metagabbro in Maru area. The objectives of this work were to study field, mineralogy, and geochemical characteristics of gold bearing quartz veins and soils. Euhedral and polygonal magnetite with hematite constituted the major ore minerals. Quartz occurred as main gangue phase with appreciable sericite and chlorite. The mineralogy of soil retrieved from twelve minor gold fields examined with X-ray diffraction is quartz ± albite ± microcline ± muscovite ± hornblende ± magnetite ± illite ± kaolinite ± halloysite ± smectite ± goethite ± vermiculite ± chlorite. The concentration of gold in quartz vein varies from 10.0 to 6280.0 ppb with appreciable Pb (3.5–157.0 ppm) and ΣREE (3.6 to 82.9 ppm). Gold content in soil varies from <5.0 to 5700.0 ppb. The soil is characterized by As ± Sb gold’s pathfinder geochemical association. Multidata set analysis revealed most favourable areas for gold. Possibility of magmatic fluids as part of ore constituents is feasible due to presence of several intrusions close to quartz veins. Based on field, mineralogical, and geochemical evidences, ore fluids may have been derived from fracturing, metamorphic dewatering, crustal devolatilization of sedimentary, gabbroic protoliths, and emplaced in an orogenic setting.

Gold Exploration and Potential of the Appalachian Piedmont of Eastern Alabama

ABSTRACT: The discovery and production of gold from epithermal and volcanogenic massive sulfide deposits in the Carolina slate belt of the southern Appalachians perhaps have overshadowed the gold potential of orogenic gold deposits in relatively higher grade metamorphic terranes of the southern Appalachian Piedmont. There has been a limited amount of exploration in the non-Carolina slate belt southern Appalachians since the early 1980s. Here we describe some of the recent exploration activity and geology of gold occurrences in the most productive part of the Alabama Piedmont, including the Goldville and Devil’s Backbone districts. In this area, there is a strong geochemical association of gold and arsenic in bedrock, saprolite, and soils, which reflects the mineralogical association of gold with arsenian pyrite and arsenopyrite in mineralized zones.