Hypergenesis Zone Research Articles

Nature of ree accumulation in clayey interlayers and coals in Karaganda coal basin

It is the first completed complex mineralogical and geological research of REE (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in the coals of Karaganda coal basin in Central Kazakhstan. This paper presents the results of the research of REE (from lanthanum to lutetium and Y) distribution in 85 samples of coal and clayey interlayers of stratum k7 of Karaganda coal basin in the faces of Saranskaya, T.Kuzembayev, Aktasskaya mines. The ultimate composition of clayey interlayer and coal samples was analyzed by the methods of inductively coupled plasma optical emission spectroscopy and inductively coupled plasma mass spectrometry (ICP-OES and ICP-MS). Research of the lateral and vertical discontinuity of the total REE concentration has indicated the presence of mixed types of REE distribution in coals, which supposes various forms of REE migration and different mobility of heavy and light lanthanides within the hypergenesis zone. The established lanthanum-ytterbium (La/Yb) ratio in the coal, which is normalized to UCC and equals La/Yb<1, relates to the coals with Н type of REE distribution, and the one that equals La/Yb>1 and normalized to chondrite belongs to the coals with L type of REE distribution, which allows making conclusions on the presence of independent sources and different mechanisms of REE accumulation in the sediments of Karaganda coal basin. It is also established that the La/Yb ratio grows from coals to clayey interlayers, which indicates a predominantly clastogenic mechanism of REE input to the coals. The prevailing mineral form of the REE in the coal and clayey interlayer samples from the Karaganda coal basin is light lanthanide phosphates. Sparry crystals with CeLaNdPO composition were found in the coal and clayey interlayer samples. It was established that xenotime is the main deportment for Y in many coals.

Ore deposit prospecting using the chlorine and bromine secondary dispersion halos

The Cland Brions, that form complex compounds with metals, produce secondary dispersion halos in the hypergenesis zone at Au, Ag, Cu, Pb, and Zn ore deposits which ore bodies are controlled by fracturing and fault structures. The appearance of anomalies of the highly mobile water-soluble ions, manifested on the surface and in the wall rocks, is explained by their transfer from the deep sources to the surface by a gas flow. The migration of the ions to the earth's surface and further into the atmosphere is influenced by many factors (atmospheric pressure, temperature, humidity, rock porosity, etc.) that complicate the observation results.

Bicarbonate waters in hydrogeological complexes of the hypergenesis zone of the Southern Cis-Urals

The article deals with the formation and distribution of bicarbonate groundwater in the hydrogeological complexes of the hypergenesis zone of the Southern Cis-Urals. Particular attention is paid to the issues of the distribution of bicarbonate groundwater in the hydrogeological section, which are of the greatest practical importance for the purposes of drinking water supply in the region. On the basis of long-term complex field and experimental studies, it has been established that the formation of the chemical composition and distribution of these waters in hydrogeological complexes is subject to the laws of vertical hydrogeodynamic and gas-hydrochemical zonality. The influence of technogenesis on the qualitative composition of these waters is noted.

Mineralogy and geochemistry of tellurium in the some mining sites of Transbaikalia

The first results of the study of the occurrence and mineral forms of tellurium in hypogenic and hypergenic conditions on the example of some deposits in Transbaikalia are presented in the article. Their paragenesis and the variations of tellurium content in ores and the hypergenesis zone are considered. Experiments on water leaching of tellurium, bismuth, lead, uranium and silver were carried out. The physicochemical model of mineral associations with the participation of these elements in conditions of the hypergenesis zone was calculated.

Major Causes of Age Distortion in Uranium-Lead Isotopic Radiogeochronology

The causes of isotopic age distortion that may occur during the dating of endogenous geological processes (rocks) by the uranium-lead isotopic method are considered. Three groups of reasons are distinguished: mineralogical, geochemical and analytical. The main mineralogical reason for the distortion of the U-Pb isotopic age is the multistage crystallization of geochronometer minerals, which is manifested, for example, in zircon, in the anatomy of their crystals. It was concluded that in order to obtain reliable information about the time course of geological processes for complex crystals (primarily zircon), local uranium-lead isotope dating methods ("SHRIMP", LA-ICP-MS, etc.) should be used. The geochemical reasons include the discrepancy between the isotopic composition of impurity lead and the isotopic composition of corrective lead (abnormal isotopic composition of ordinary lead) and the polystage history of the development of the uranium-lead isotope system. It is noted that the most probable reason for the violation of the uranium-lead isotope system by zircons in the hypergenesis zone is the entrapment of uranium by defects in the crystal structure and cracks, and the predominant loss of uranium in monazite. At the same time, the loss of uranium by monazites depends on the composition of the acids. It is indicated that washing monazites in a weak solution of nitric acid leads to the appearance of a significant reverse discordance, while no loss of lead is observed. The same operation in a weak solution of hydrochloric acid leads to the preferential leaching of ordinary lead. For analytical reasons, the lowest accuracy of determining the prevalence of the 204Pb isotope (204Pb/206Pb ratio) is indicated. The impact of contamination of samples dated (method TIMS) by lead and uranium from reagents is considered. It is clear that the contamination of multi-grain samples (1-2 mlg) of minerals with uranium and lead from reagents with a modern isotopic composition, in a blank test of lead 10–9 g (the ratio of the mass of Pb of the sample to the mass of Pb from the reagents of 40 to 1) is not significant affects dating results (isotopic ratios of 207Pb/206Pb, 207Pb/235U and 206Pb/238U). A blank sample of uranium is usually 2 orders of magnitude smaller (10–11-10–12 g). A strong inverse relationship between the degree (proportion) of radiogenic lead contamination of radiogenic lead aliquots on the isotopic composition of lead and the calculated values of the lead content in the sample was revealed. When an aliquot for determining the content of uranium and lead is contaminated with ordinary lead from the reagents, the smallest distortion of the calculated value of the lead content occurs when the ratio of sample lead to tracer lead is 1:1, while a slightly smaller relative distortion of the lead content is noted with increasing age of the radiogenic lead of the samples.

ОЦЕНКА ВЛИЯНИЯ ГИПЕРГЕНЕЗА В ХРАНИЛИЩАХ ОТХОДОВ ПЕРЕРАБОТКИ МЕДНО-КОЛЧЕДАННЫХ РУД НА ВЫБОР ТЕХНОЛОГИЧЕСКИХ СХЕМ ИХ РАЗРАБОТКИ

The problem of involvement of lying wastes of copper-pyrite ore processing into industrial exploitation considering transformation of their material composition and structure in the process of storage is considered. By the example of old tailings dump of Sibai concentrator patterns of humidity, pH of environment and solubility of mineral forms on depth of technogenic massif are established. The peculiarities of the structure of the technogenic mineral formation are marked; based on the results of geological and evaluation works the hypergenesis zone, which differs by mineral composition, structure and properties of the stockpiled raw materials, is singled out. A method of zoning the technogenic formation by depth to choose the technology of its development is proposed.

Transformation of siderite in the zone of hypergenesis

Transformation of siderite in the zone of hypergenesis

Глинистые минералы пелоидов оз. Саган-Нур в Тункинской долине как показатели анаэробных условий литогенетических процессов

The results of the study of chemical, granulometric, and mineral compositions of sapropelic bottom silts from Sagan-Nur lake are presented in four cores of the layer as thick as 45 cm that overlies sandy lacustrine deposits. The silt is used as therapeutic mud (peloids). Clay minerals in sedimentary deposits are identified using X-ray diffraction analysis and scanning electron microscopy. Finely dispersed clay minerals of peloids are considered as indicators of anaerobic conditions of lithogenetic processes in the hypergenesis zone.

Rare Alkali Metals in the Waters of Lithium-containing Deposits in Eastern Transbaikalia

The results of hydrogeochemical studies on the content of rare alkaline elements in man-made waters of mining facilities at Zavitinskoye, Orlovskoye, and Etykinskoye rare metal deposits of Eastern Transbaikalia are presented. Concentrations of these elements are determined both by the content in the ores and rocks of deposits and by their water-migration properties. It was found that the acidic sub-basement waters of the Orlovskoye and the quarry waters of the Zavitinskoye deposits contain abnormally high concentrations of lithium, up to 3.74 and 3.88 mg / L, respectively. The high content of lithium (Li) in the waters of these deposits was determined relative to the average values for the waters of the hypergenesis zone, as well as the standards of maximum permissible concentrations (MPC) of chemicals for water bodies used for fisheries, drinking water, and other activities.

Mineralogical and Geochemical Features of Native Gold From Placers of the Evota Gold-Bearing Region (Russia, Aldan Shield)

Evota gold-bearing region is located in south of Republic Sakha (Yakutia) within the Nimnyr terrane of Aldan shield. A large numbers of gold-bearing placers are known on studied territory, but the primary sources for them have not been established. In this work, based on the study of the mineralogical and geochemical features of gold from alluvial deposits of the Evota gold-bearing region, possible genetic types of primary sources are considered. Obtained data showed that native gold in the studied objects has a very high, high and medium fineness. The roundness of gold is different. Almost ore crystals with sharp edges and well-rounded individuals with polished faces were found. The fineness of the studied gold grains was determined by microprobe analyzer Cameca Camebax-micro and varies in the range from 812 to 1000 %⁰. A thin (up to 20 μm) high-grade rim was found in two grains (cr. Zolotoy). The central part of one of them has a fineness of 865 %o, and in the edge part it reaches 1000 %⁰, which indicates that this gold was in the hypergenesis zone. Admixture elements determined as traces and are presented Cu, Pd, Fe, Ni. Minerals-microinclusions - quartz, potassium feldspar, pyroxene, staurolite, maldonite, bismuthite revealed in gold grains. In some watercourses, for example, in the creek Sukhoi, only very high fineness gold (993-1000 %⁰) was found. The presence of high-grade gold (cr. Sukhoi), intergrowths of gold with bismuthite (cr. Zolotoy), as well as inclusions of maldonite (cr. Yagodny) gives opportunity for assuming that primary sources could be basic ores such presented in the P. Pinigin deposit. At the sites (cr. Elovyi, r. Evota), both medium-grade and very high-grade gold were found, the fineness range varied from 827 to 998 %⁰. The presence of gold with medium fineness and good roundness in studied watercourses probably indicates an additional supply of gold from primary sources formed as a result of the alkaline magmatism development of the Mesozoic age. Thus, for gold with high and very high fineness by admixture-elements, chemical composition and microinclusions, a genetic relationship with primary sources similar to the P. Pinigin deposit was found; for gold grains with medium fineness, formation in gold-ore mineralization characterized for the Mesozoic stage ore development such in deposits of Central-Aldan ore region is assumed.

Hydrogeological dissimilarity of geodynamically different terranes

The article presents and analyzes the data on ground waters of active (suprapermafrost) and hindered (subpermafrost) water exchange of geodynamically different terrains in order to prove the hydrogeological importance of their historical and tectonic characteristics. On the example of Trans-Polar Chukotka it is shown that, under suprapermafrost conditions, the ubiquitous eluvial-deluvial nappes are the most water-abundant on the terrane – a fragment of the passive continental margin, whereas they are the least water-abundant on the terrains of the active margin. Hydrogeological situation changes under subpermafrost conditions: more permeable and water-retaining rocks compose the terranes of the active margin. These differences are associated with the level of rock tectonic decompaction and, accordingly, with different intensity of weathering processes in the terrane rocks of different geodynamic origin in suprapermafrost and subpermafrost conditions. The hypergenesis zone on the terranes of the passive continental margin features coarse-grained rock weathering products accumulated in relatively calm geological and historical environments, the aggregate is sandy. The terranes of the active margin, which underwent long-term subvertical and subhorizontal displacements contain more fine-grained weathering products; the aggregate includes sandy loam and clay sand. Since the permafrost strata in both Trans-Polar Chukotka and Eastern Siberia is greater than the depth of hypergene transformations, the terranes of the active continental margin, the rocks of which were impacted by tectonic decompaction processes, mainly of a strike-slip and thrust nature, feature greater water abundance in subpermafrost conditions.

ОТКУДА СТАРТУЕТ ГЕОЛОГИЧЕСКОЕ ВРЕМЯ?

In the earth sciences, there is a persistent contradiction between modern ideas about the age of the planet and the concept of V.I. Vernadsky about the geological eternity of life. According to Vernadsky, the absolute age of the rock indicates only the time of its last metamorphism, but not the age of the Earth. It is no coincidence that the pregeological substance of a cosmic formation of the planet has not been found. Such substance does not exist because any mineral complex and rock begins to form in the hypergenesis zone. Vernadsky argued that geological history was equal in duration to the existence of the biosphere and its duration was measured by biological time. His concept is confirmed by current biogeochemistry. The history of the biosphere practically coincided with the "canonical" age of the Earth. In a cosmological sense, the picture of the universe cannot be built without the concept of the geological eternity of the biosphere.

Comparison of isotope data obtained with Sm-Nd and Re-Os methods for minerals and rocks from the Ozernoe ore occurrence, Salla-Kuolajarvi belt

Sm-Nd isochrone, drawn for rock-forming and sulfide minerals from the Ozernoe ore occurrence, indicates albitite age of 1,759 ± 11 Ma. It shows synchronous formation of albitite and sulfide mineralization, and fully corresponds to the earlier defined age of rutile in albitite (1,757 ± 7 Ma U-Pb, n = 3, MSWD = 0.2), and Rb-Sr isochrone age 1,754 ± 39 Ma for biotite, apatite, albite, and WR. Recently published Re-Os ages of molybdenite 1,872 ± 23 Ma and chalcopyrite 1,891 ± 230 Ma indicate more ancient age of sulfide mineralization. These figures are in conflict with the age of rock-forming minerals, defined with Sm-Nd and Rb-Sr methods. The possibility of use of molybdenite from the Salla-Kuolajarvi belt for rock dating has been considered, and low reliability of Re-Os method for it has been shown. The reasons are the following: 1) extremely uneven distribution of Re in molybdenite, where Re content varies 1 wt.% even within one and the same grain, and 2) openness of the Re-Os system after molybdenite crystallization, Re is mobylized and partly removed from the mineral in the zone of hypergenesis. Removal of Re from molybdenite promotes erroneous ancient age of the molybdenite. According to the equations of radioactive decay, the age would be 110-130 Ma bigger if 5-6 % of Re is taken away. The conclusion is that molybdenite must be studied in detail, proved to be homogenous and unaltered, before it is used for Re-Os dating. In the other case the results will be not reliable.

Gold-tourmaline mineralization in carbonaceous shales of the Kumak deposit (South Ural)

The article discusses the geological structure of the Kumak gold ore deposit, confined to the Early Carboniferous Anikhov graben of the East Ural uplift. It is composed of sericite-quartz-carbon and quartz-carbon-tourmaline schists of the Bredy Formation (C1bd). Black shale deposits are carbonaceous type and belong to terrigenous-carbonaceous and silicon-carbonaceous formations. Among the main minerals in shales are noted: quartz, sericite, carbonates, sulfides, tourmaline and carbonaceous matter. The field is characterized by a wide variety of gold ore mineralization. Rich ore zones are noted at the intersection of the East Anikhov faults oriented in the north–south direction and the branching tensile fractures in the north-north-east and north-west directions. In the ore mineral association prevailing here, finely dispersed gold is associated with small crystals of pyrite, arsenopyrite and concentrates nearby abundant tourmaline areas. The fine intergrowth of tourmaline and gold indicates the synchronism of their formation and allows us to distinguish a quartz-tourmaline gold ore formation within the Kumak deposit, comparable with a number of objects in East Transbaikal and Tuva. The most probable source of tourmaline mineralization in sericite-quartz-carbon schists could be metamorphically transformed boron-containing marine sediments saturated with clay particles and Corg. The microprobe study of gold grains taken from carbonaceous shales and weathering crusts made it possible to attribute them to the high-grade (919–1000) type, which is the leading one in the gold ore mineralization of the considered deposit. It is established that in the zone of hypergenesis, gold grains are not homogeneous. Here, secondary redeposition of gold takes place in the form of small spongy high-grade aggregates, as well as the formation of a rim on some grains with clear signs of refinement and purification from impurity elements. The geological works were carried out under State Contract No. 0246-2019-0078. The analyses were supported by the regional Grant for Science and R&D, Agreement No. 23 dated August 18, 2019. The studies into gold composition were executed in the framework of state-financed scientific topic No. AAAA-A19-119072390050-9. The authors express thanks to S. A. Yagudin for the analysis implementation and to E. O. Kalistratov for the help in description of polished sections. Further thanks are extended to R. S. Kisil and V. S. Panteleev for the help in the field works.

Experimental Study of Fluorine Mobilization from Igneous Rocks

The paper presents experimental data on fluorine leaching from igneous rocks (dacite, rhyodacite, and trachyrhyolite) and greisen with distilled water and 0.01 M HCl, CH3COONa, NaHCO3, and Na2CO3 solutions. Fluorine leaching is proved to be proportional to its content in the rocks and depends on pH of the aqueous solution: the equilibrium concentrations of fluoride are minimal in the near-neutral solutions and increase in acidic and alkaline ones. The spatial variability of fluorine concentrations in waters of the hypergenesis zone is likely controlled primarily by the petrographic composition of rocks and processes that determine pH of the aqueous solutions.

Ecological and Geochemical Features of the Underground Waters of the Semipalatinsk Test Site

The results of the study of ecological and geochemical features and assessment of the water quality of water sources located on the territory of the Semipalatinsk test site are presented. The studied waters are diverse in chemical composition: 14 % of the samples had hydrocarbonate, 69 % – sulfate, and 17 % – chloride types of waters. On the basis of the revealed features of the elemental composition of the underground waters of the Semipalatinsk test site, decreasing series of excess of the average concentrations of elements in water in relation to the composition of waters of the zones of hypergenesis and continental salinization were constructed: U14> Mo8> Sr8> V3(hypergenesis zone), U5> Mo3> Sr3> V2(zone of continental salinization). For the groundwater of the Semipalatinsk test site, specific elements were identified, such as U, Mo, Sr and V. The water quality was assessed for the studied chemical components based on comparison with the standards of the Republic of Kazakhstan and the World Health Organization (SaNPiN No. 209, WHO 2011).

Characteristics of uranium mineralization in the Tin-Seririne sedimentary basin (Algeria)

This article presents the results of studying the uranium mineralization of various parts of the Tin-Seririne sedimentary basin located in the southern part of the Hoggar massif in south-eastern Algeria. Mineralization of uranium is localized at different stratigraphic levels: in altered rocks of the Archean basement and unconformity overlying basal conglomerates (Tahaggart region), and in Devonian sandstones (uranium ore occurrences Tamart-N-Iblis, Timouzaline, etc.). For laboratory studies, 07 samples were taken: As and A1 granites, Tedjart, Timouzaline and Tamart-N-Iblis sandstones, gneisses and conglomerates of the Tahaggart deposit. The samples were examined using gamma spectrometric, chemical and microprobe analyzes. Mineralization is represented by minerals of hexavalent uranium: autunite, torbernite, carnotite, vanuralite and uranophane. The hypergenesis zone of the deposit, it is noted that the geochemical features of the formation of uranium mineralization are typical for regions of arid climate. The arid climate corresponds to oxidative processes of chemical weathering, with weakly alkaline or neutral uranium-bearing solutions. When studying samples taken from different stratigraphic levels, a difference in mineral composition was noted, which indicates some differences in the conditions of formation of uranium mineralization.

Geochemistry of fresh groundwater in the Altai–Sayan folded area and adjacent areas of the West Siberian plate

This study investigates the regional geochemical features of groundwater in the hypergenesis zone of the Altai–Sayan fold zone and in the adjacent structures of the West Siberian plate (hereafter simply called the Region). The hypergenesis zone of the Region contains widely spread freshwater and (to a lesser extent) low-saline waters. The patterns of changes in the water composition, the migration forms of various macro- and micro-components, and the equilibria of waters with various minerals, are analysed. The hypergenesis zones of the Altai–Sayan folded area and the adjacent structures of the West Siberian plate are characterised by high-altitude and latitudinal hydrogeochemical zonality, respectively. The total salinity of the groundwater increases with the lowering altitude conditions and changing landscape conditions in the Altai–Sayan region, and with the latitudinal changes of landscape in the adjacent structures of the West Siberian plate. In the same sequence, the contents of most mobile chemical elements and the role of complex forms of element migration increases, and the variety of minerals in equilibrium secondary formations expands. The main parageneses (geochemical water types and the associations of secondary newly-formed minerals) in the Region are oxide-hydroxide-forming, aluminosilicate forming, carbonate forming, and sulphate-forming. The parageneses are formed in genetic unity.

Radioactive Rock Dumps in the Elkon Uranium Ore Area (South Yakutia)

We examine the geographical features in the distribution and the radiation parameters of radioactive rock dumps in the Elkon uranium ore area on the territory of South Yakutia. It is pointed out that the dumps under study are geomorphologically located on the Elkon horst which is a protrusion of crystalline basement rocks, towering over the territory of the Aldan highlands. It is found that most of these dumps lie within streambeds and in the bottoms of mountain rivers of the zone of hypergenesis and, geochemically, they are influenced by steep-slope topography, a cold humid climate and mountain-taiga vegetation dominating land cover. It is shown that these rock dumps were formed in the last third of the 20th century, during a large-scale and intense geological exploration for radioactive raw materials in this area. Radiation parameters of the dumps under study, such as the gamma radiation exposure dose, the content of 238U, 232Th and 40K, as well as the effective specific activity of these radionuclides were determined. It is found that the most active rock dumps, in their radiation parameters, approach radioactive ores. The dumps under study were ranked according to the degree of radiation danger to the population on the basis of the particular values of the gamma radiation exposure dose and effective specific activity of these radionuclides. It is established that the main source of radioactive contamination of soil and vegetation cover and the surface waters in the Elkon uranium ore area on the territory of South Yakutia are 40 rock dumps which are unevenly distributed in the total area of about 500 km2 of the mountain-taiga permafrost landscapes. It is determined that more than half of these dumps, in their radiation parameters, are classified as hazardous and specially hazardous.

Ecological and Hydrogeological Problems of the Old Industrial Regions of the Middle Urals (Russia)

Mining of mineral deposits leads to the formation of mining landscapes, within which specific hydrogeochemical systems arise. Following the dewatering to the depths of tens and hundreds of meters, processes of technogenic hyper-genesis and mineral formation are developing, especially in areas where the continuity of rocks is disturbed. Here, the sulfuric acid weathering crust is formed, which contains secondary minerals, including readily soluble crystalline hydrates of sulfates. The article presents the results of the analysis of the hydrochemical situation within the abandoned Levikha mine (Middle Urals). It is shown that the reason for the formation of unloading of acid mine waters on the surface during postmining is the change in the hydrodynamic conditions (cessation of the drainage and the filling of the depression cone), the dissolution of secondary minerals in the technogenic zone of hypergenesis (in the zones of collapse and displacement). The mass consumption of components at the post-operational stage is comparable to the rate of oxidative weathering of sulfides during the operation of the dewatering. The half-life of the components is about 5 years, and the formation of contaminated mine waters will last at least 50 years. These results are the basis for determining the strategy and tactics of planning work to eliminate the accumulated damage to the environment of the mining landscapes of the Middle Urals at the post-mining stage.