Studies of mineral-forming processes in modern peat bogs can shed light on metal concentrations and their cycling in similar environments, especially in geological paleoanalogs. In terms of the mineralogical and geochemical evolution of peat bog environments, the Vasyugan Swamp in Western Siberia is a unique scientific object. Twelve peat samples were collected from the Vasyugan Swamp up to the depth of 275 cm at 25 cm intervals. The studied peat deposit section is represented by oligotrophic (0–100 cm), mesotrophic (100–175 cm), and eutrophic (175–275 cm) peat, and this is underlain by basal sediments (from 275 cm). About 30 minerals were detected using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The observed minerals are divided into detrital, clay, and authigenic phases. The detrital minerals found included quartz, feldspar, ilmenite, rutile, magnetite, zircon, and monazite. When passing from basal to oligotrophic bog sediments, the clay minerals changed from illite-smectite to kaolinite. Authigenic minerals are represented by carbonates (calcite and dolomite), iron (hydro-)oxides, galena, sphalerite, pyrite, chalcopyrite, Zn-Pb-S mineral, barite, baritocelestine, celestine, tetrahedrite, cassiterite, REE phosphate, etc. The regular distribution of mineral inclusions in peat is associated with the (bio)geochemical evolution of the environment. The formation of authigenic Zn, Pb and Sb sulfides is mainly confined to anaerobic conditions that exist in the eutrophic peat and basal sediments. The maximum amount of pyrite is associated with the interval of 225–250 cm, which is the zone of transition from basal sediments to eutrophic peat. The formation of carbonate minerals and the decreasing concentration of clay in the association with local sulfide formation (galena, sphalerite, chalcopyrite, stibnite) begins above this interval. The peak of specific carbonation appears in the 125–150 cm interval of the mesotrophic peat, which is characterized by pH 4.9–4.5 of pore water. Kaolinite is the dominant clay mineral in the oligotrophic peat. Gypsum, galena, chalcopyrite, sphalerite, and relicts of carbonate are noted in association with kaolinite. Changes in oxygen concentrations are reflected in newly formed mineral associations in corresponding intervals of the peat. This can be explained by the activity of microbiological processes such as the anaerobic oxidation of methane (AOM) and bacterial sulfate reduction (BSR), expressed in specific carbonatization (100–225 cm) and sulfidization (175–250 cm), respectively.

Geopolymers are high-performance, cost-effective materials made from industrial waste that ideally fit the needs of 3D printing technology used in construction. The novelty of the present work lies in the investigation of methods to mix geopolymer concrete from fly ash (FA) class F, ground granulated blast furnace slag (GGBS), and raw calcined kaolin clay (RCKC) to determine the mixing procedure which provides the best mechanical strength and structural integrity. The experimental results show that aluminosilicates with different reaction parameters when mixed one after another provide the optimal results while the geopolymer concrete possesses the highest compressive strength and the denser structure. The results demonstrated that the reactivity of GGBS, FA, and RCKC increased for different depolymerization speeds of the selected aluminosilicates. This research will provide results on how to improve the mixing order for geopolymer synthesis for 3D printing demands. The highest compressive strength and denser structure of geopolymer concrete is achieved when each type of aluminosilicate is mixed with an alkaline medium separately.

Link for citation: Korovkin M.V., Ananyeva L.G., Zherlitsyn A.A., Kondratiev S.S., Savinova O.V., Kurskaya V.S. Assessment of crystallinity degree of quartz raw materials. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 59-67. In Rus. The relevance of research is determined by the need to assess the degree of transformation of quartz raw materials in its natural occurrence, as well as, changes in the properties of raw materials and products are exploited under various operating conditions. X-ray diffraction and Infrared spectroscopy was used to assess the degree of crystallinity of various crystalline quartz materials and products made of silicon dioxide, which showed satisfactory convergence of results and can be recommended for use in world practice. Objects: artificially grown quartz, including samples of synthetic quartz with an admixture of aluminum, zone-colored single crystal of quartz with an admixture of two and ferric iron; natural crystals of amethyst, smoky quartz, optical quartz; samples of fused quartz, products made of technical and optical quartz and silicate glass; as well as fine-grained samples of quartzites, including their micro- and nano-sized fractions. Methods: optical and electron scanning microscopy, X-ray spectral and analysis, infrared spectroscopy, X-ray diffraction. Results. The paper shows that the degree of crystallinity of quartz raw materials and products based on it is determined by the presence of a structural ordering in the near zone that characterizes the crystalline state corresponding to the a-quartz phase, which is confidently recorded by XRD and FTIR methods. The local disorder of high-purity quartz or quartzites having various impurities or defects in their structure that arise under the influence of external influences or exploitation causes deterioration of their properties and decrease in the degree of crystallinity.

Relevance. Gold-bearing weathering crusts are widespread in the Tom-Yaya interfluve, but the criteria for predicting their gold content, including geochemical ones, have not been adequately developed. Aim. To identify the geochemical features of the weathering crusts of the Tom-Yaya interfluve to resolve issues of predicting their gold content. Object. Weathering crusts from the rocks of the Paleozoic basement of the Tom-Yaya interfluve. Methods. The chemical composition of weathering products was determined by ICP-mass spectrometry. Core samples of 36 wells for 20 elements were analyzed. The results obtained were processed in the statistical analysis software package Statistica. The main parameters of the distribution of chemical elements in the profiles of gold-bearing and non-gold-bearing weathering crusts were calculated, discriminant and factor analyzes were carried out. Results. Statistically significant differences in the chemical composition of the weathering profile zones were established. In weathering of non-gold-bearing rocks, the removal of P, Mn, Co, Ni, Zn and the accumulation of Cr, Mo, Ag, Sn, Sb, Hf, Tl, Pb, Bi occur with the indifferent behavior of Au, As, Fe, Cu. Gold-bearing weathering crusts are formed in mineralized zones and are initially enriched in Au, As, W, Sb, and, to a lesser extent, Cu, Zn, Pb, Bi, Tl, Hf, Sn. The average content of gold and most satellite elements (except Pb) decreases during the weathering of mineralized zones, but the dispersion increases many times, as a result of which areas of secondary enrichment in gold and satellite elements Sb, As, Ag, Sn, Tl, Co, Cu, Zn, Cd, Bi appear within the zones of hydrolysis and hydration. Geochemical associations characteristic of residual weathering crusts are largely preserved in redeposited crusts, where As, Sb, W, Cd, Ag, Sn, and Hf are accumulated together with gold.

The relevance of the modern volcanism study is to understand the complex processes of the magma differentiation, assimilation and mixing that recorded in the mineralogical, structural and petrochemical features of volcanic rock units. On the other hand, economically significant deposit of non-ferrous and noble metals is often associated with basic volcanism of increased alkalinity in modern island-arc systems. The main aim of this work is to study and interpret the mineralogical and petrochemical features of the lavas from the active Batur volcano (Bali Island, Indonesia). Objects: samples of lava from the 1964 Batur eruption. Methods. The rock units of modern island arc lavas and the minerals found in them have been studied by optical and electron microscopy using energy dispersive spectroscopy analysis. The major elements of the rock units were obtained using silicate analysis, while trace element composition - using inductively coupled plasma mass spectrometry analysis. As a result of the conducted studies it was found that all samples of the lavas from Batur volcano have porphyry structure and contain phenocrysts of plagioclase (17...23 vol. %), olivine (3 vol. %) and pyroxene (2 vol. %) located in the fine-grained ground mass containing plagioclase, titanomagnetite, pyroxene and volcanic glass. The phenocrysts of plagioclase are characterized by a "sieve-textured domains" structure, with oriented melt inclusions (similar to 0,05 mm) containing primary silicate and sulfide melts. The petrochemical parameters of the Batur lavas suggest that they correspond to highalumina basalts (Al2O3 >= 18,0). The complex structure of zonal plagioclase phenocrysts is consistent with the rapid cooling of the initial melts, when the released plagioclase cannot come into equilibrium with the remaining liquid magma. Its bulk chemical composition corresponds to labrador-bytownite. Olivine reveals several variants for iron redistribution in its composition including zonal crystals with iron accumulation in the marginal parts of grains, specific "excolutions structures" and homogeneous olivine crystals with Mg#(Fo) [=Mg/(Fe2++Mg)*100 % atomic ratio] component similar to 66,0. The increased iron content and manganese oxide alloy (Mn2+) in olivine may indicate that the Batur lavas are derivatives from the olivine basalt with an alkaline bias. Presumably, during the period of intense volcanism Batur volcano eruption in 1964, the magma chamber was periodically enriched with olivine basalt at some regularity. Further, this melt rose to the upper part of the chamber, followed by fractionation of olivine and clinopyroxene during crystallization of plagioclase and their accumulation in the upper part of the magma chamber. During the period of the input of a new portion of the initial melt, the existing mixture had not come into equilibrium with the incoming portion of the melt, has erupted to the surface and formed the lavas of high-alumina basalt. The presence of covellite and chalcopyrite globules in melt inclusions in the phenocrysts of plagioclase may be the evidence of the existence of a highly fractionated sulfide melt at a deeper level.