Primary Dispersion Research Articles

Primary Dispersion and Some Morphological Characteristics of Migrating Larvae of the Sakhalin Sculpin Cottus amblystomopsis (Cottidae) in the Malaya Khuzi River (Sakhalin)

Primary Dispersion and Some Morphological Characteristics of Migrating Larvae of the Sakhalin Sculpin Cottus amblystomopsis (Cottidae) in the Malaya Khuzi River (Sakhalin)

Vulnerability and Resilience of Slovak Municipalities in the Era of Austerity

Abstract The consequences of periods of austerity, generally connected with economic crises, are not only reflected in the financial performance of local governments but also in the range in which they can face shocks. Monitoring the vulnerability and resilience associated with these shocks and the subsequent impacts on the financial situation of Slovak municipalities points to financial resilience, the ability to be proactive or, on the contrary, to be passive as a reaction to evolving environmental conditions. The paper examines the ability of 2,923 Slovak municipalities in the period 2005 - 2022, according to their size categories, to respond to periods of austerity in the economic reality of the Slovak Republic: The Global Financial Crisis from 2009 and the recent ongoing economic crisis arising from the crisis COVID-19, the subsequent military crisis in Ukraine, and the related energy crisis (multi-crisis). The resilience and vulnerability of Slovak municipalities, considering the size categories, are measured by employing a primary dispersion measure as the standard deviation of six financial indicators mirroring the local government’s performance in the form of indexes linked to 2005. The results confirm the vulnerability of Slovak local governments in considered eras of austerity with relevant recovery periods, demonstrating a considerable degree of resilience. Besides, we reveal other structural breaks in the monitored period, which influenced the economic circumstances of Slovak municipalities, too.

Research Progress of New Generation of Aluminum–Lithium Alloys Alloying

Aluminum–lithium alloy, being the lightest aluminum‐based alloy, holds significant potential for applications in the aerospace and military sectors. Currently, alloying treatment stands as a crucial method for enhancing the comprehensive performance of aluminum–lithium alloy. This article provides an overview of the production process of aluminum–lithium alloys, encompassing smelting and deformation processing characteristics. Additionally, it outlines the developmental history of the chemical composition for the primary grades of aluminum–lithium alloy, detailing the copper (Cu) and lithium (Li) content of the main alloying elements. And discusses the influence of various microalloying elements on the alloy's properties. Additionally, it summarizes the structure, properties, and precipitation morphology of the three primary strengthening phases formed by the alloying of aluminum–lithium alloys: T1 (), (), and (). The analysis also examines the impact of anisotropy on the mechanical properties of the primary dispersion. Finally, the article addresses the challenges involved in alloying aluminum–lithium alloys and proposes key research directions for element composition design.

Typomorphism of Autigenic Gold in Riphean Sandstones of the Kyvvozhskoye Goldfield (Volsko-Vymskaya Ridge, Middle Timan)

The results of a comprehensive study of the morphology, composition and the internal structure of fine autigenic gold, first discovered in bedrock on the area of the Kyvvozhskoye goldfield, are presented. It has complex specific rounded-lumpy, lumpy-branched aggregate forms and a smooth growth surface without traces of mechanical wearing. X-ray studies (Debye-Scherrer method) show that reflexes in the form of dashed rings are characteristic of debyeograms of this native gold, which, according to the authors, indicates the absence of exogenous deformations of it. The internal structure of all the studied gold pieces is characterized by a relatively homogeneous inner area and a thin (~1 µm) contrasting enriched with silver low-grade rim. All the particles of the studied native gold have approximately the same average fineness (899–918‰). As a mechanism for the formation of the found autigenic gold, its crystallization is assumed by filling of the free pore space of the host sandstones. Its presence in Riphean rocks is considered as an indicator of the primary dispersion halos and is a direct search sign of the development of potentially productive gold mineralization in this part of the Middle Timan.

Developing a Lagrangian sediment transport model for open channel flows

A three-dimensional stochastic Lagrangian particle tracking sediment transport model is developed to solve the discrete advection–dispersion equation using a combination of empirical dispersion equations. The performance of three widely-used longitudinal dispersion coefficient equations was examined to select one of them as the primary dispersion equation term in the developed model. Also, a conditional empirical equation was used to consider the effect of vertical dispersion term in top layers near the water surface. The performance of particle tracking model (PTM) to calculate the sediment concentration was evaluated for various sediment classes (very fine sand, fine sand, and medium sand) using available laboratory dataset. Multiple statistical measures were calculated using the Taylor diagram for each dispersion equation. Based on the result, the developed particle tracking model estimated the suspended sediment concentration in a rectangular open channel with a correlation coefficient (R) of 0.96, standard deviation (STD) of 0.262, and root mean square deviation (RMSD) of 0.06 for three different sediment classes proving the acceptable accuracy of the developed model for different range of sediment gradations. In addition, the accuracy of PTM was compared to recently developed models. Comparison between the particle tracking model and the analytical solution of the advection–dispersion equation showed that the developed model predicted the maximum concentration of suspended sediment 6% and 9.4% lower than the analytical solution result for 30 and 50 s simulation time in the straight channel, respectively. However, there was a good agreement between the longitudinal and transverse sediment concentration distribution from the model and the analytical solution approach. The result of the sensitivity analysis and validation process showed that the model could be used to simulate sediment transport in open channel flows.

Primary dispersion patterns of gold and associated elements in Um Arka area, Allaqi Region, South Eastern Desert of Egypt.

Primary dispersion patterns of gold and associated elements in Um Arka area, Allaqi Region, South Eastern Desert of Egypt.

Impulse dispersion of aerosols during playing wind instruments.

Musical activities, especially singing and playing wind instruments, have been singled out as potentially high-risk activities for the transmission of SARS CoV-2, due to a higher rate of aerosol production and emission. Playing wind instruments can produce condensation, droplets of saliva, and aerosol particles, which hover and spread in the environmental air’s convectional flows and which can be potentially infectious. The aim of this study is to investigate the primary impulse dispersion of aerosols that takes place during the playing of different wind instruments as compared to breathing and to speaking. Nine professional musicians (3 trumpeters, 3 flautists and 3 clarinetists) from the Bavarian Symphony Orchestra performed the main theme from the 4th movement of Ludwig van Beethoven‘s 9th symphony in different pitches and loudness. The inhaled air volume was marked with small aerosol particles produced using a commercial e-cigarette. The expelled aerosol cloud was recorded by cameras from different perspectives. Afterwards, the dimensions and dynamics of the aerosol cloud were measured by segmenting the video footage at every time point. Overall, the flutes produced the largest dispersion at the end of the task, reaching maximum forward distances of 1.88 m. An expulsion of aerosol was observed in different directions: upwards and downwards at the mouthpiece, at the end of the instrument, and along the flute at the key plane. In comparison, the maximum impulse dispersions generated by the trumpets and clarinets were lower in frontal and lateral direction (1.2 m and 1.0 m towards the front, respectively). Also, the expulsion to the sides was lower.

Dispersal of Dioon edule cycad seeds by rodents in a tropical oak forest in Mexico

Predation of seeds of the cycad Dioon edule Lindl. by Peromyscus mexicanus (Saussure, 1860) has been previously documented, demonstrating that the seeds’ toxins are not harmful when combined with a varied diet. However, there is scarce evidence of P. mexicanus as a seed disperser. In a tropical oak forest in San Luis Potosí, Mexico, we experimented with seeds of D. edule and Quercus polymorpha Schltdl. & Cham., evaluating predators’ preference and recording it with photo-trapping. Burrows were sampled in concentric circles around a D. edule mother plant, and the types of burrows and condition of the seeds inside were identified with a borescope without destroying the burrows. The structure and composition of the forest were evaluated. The primary dispersion of D. edule seeds is by barochory. The rodents predate on seeds and prefer Q. polymorpha over D. edule (survival: 48.9% and 78.5%, respectively). There are more escape and multiple burrows at 3–6 m with mature oaks. Rodents forget or abandon D. edule seeds in the burrows, and such seeds germinate at 3–6 m. Peromyscus leucopus (Rafinesque, 1818) is a short-distance secondary disperser and predator of Dioon edule seeds.

Association of Metabolic Syndrome With Glaucoma and Ocular Hypertension in a Midwest United States Population.

For patients with glaucoma, metabolic syndrome was associated with higher intraocular pressure and greater central corneal thickness. Patients with metabolic syndrome were more likely to have ocular hypertension. The purpose of this study was to determine whether glaucomatous optic neuropathy, also known as glaucoma, and ocular hypertension are more likely to occur in patients with metabolic syndrome. Patients in Olmsted County, MN, were identified as having metabolic syndrome based on diagnosis codes, laboratory values, and/or medication use to meet 3 or more of the 5 standard criteria for diagnosing metabolic syndrome: systemic hypertension, hyperglycemia, hypertriglyceridemia, reduced high-density lipoprotein cholesterol, and central adiposity defined by increased body mass index. Patients with glaucoma, including primary open angle, low tension, pigment dispersion, and pseudoexfoliation, were identified using diagnostic codes. The charts of patients with glaucoma were individually reviewed to collect visual acuity, intraocular pressure, cup to disc ratio, central corneal thickness, visual field mean deviation, retinal nerve fiber layer thickness, and treatment of intraocular pressure. Patients with ocular hypertension were separately identified and similarly evaluated. For patients with glaucoma, those with metabolic syndrome had higher intraocular pressure and greater central corneal thickness compared with those without metabolic syndrome. After adjustment for central corneal thickness, there was no longer a significant difference in intraocular pressure between groups. Metabolic syndrome was also associated with the diagnosis of ocular hypertension, and although central corneal thickness trended higher in patients with metabolic syndrome, it did not attain statistical significance. In Olmsted County, though metabolic syndrome was associated with ocular hypertension and higher intraocular pressure in patients with glaucoma, the results were likely related to a thicker central corneal in this patient population.

Effects of a rotating periodic lattice on coherent quantum states in a ring topology: The case of positive nonlinearity

We study the landscape of solutions of the coherent quantum states in a ring-shaped lattice potential in the context of ultracold atoms with an effective positive nonlinearity induced by interatomic interactions. The exact analytical solutions in the absence of lattice are used as a starting point, and the transformation of those solutions is mapped as the lattice is introduced and strengthened. This approach allows a simple classification of all the solutions into states with periods commensurate or incommensurate with the lattice period and those with or without nodes. Their origins are traced to the primary dispersion curve and the swallowtail branches of the lattice-free spectrum. The commensurate states tend to remain delocalized with increasing lattice depth, whereas the incommensurate ones may be localized. The symmetry and stability properties of the solutions are examined and correlated with branch energies. The crucial importance of rotation is highlighted by its utility in continuously transforming solutions and accessing in a finite ring with a few sites the full spectrum of nonlinear Bloch waves on an infinite lattice.

Mineralogy and petrogenesis of fracture coatings in Athabasca Group sandstones from the McArthur River uranium deposit

ABSTRACT The McArthur River unconformity-related uranium deposit, located in the Athabasca Basin of Saskatchewan, Canada, is structurally hosted near the unconformity between Archean to Paleoproterozoic metasedimentary basement and the Proterozoic Athabasca Group sandstones. In this study, the mineralogy and geochemistry of fracture materials within the entire ca. 550 m thickness of the Athabasca Group sandstones and the metasedimentary (host) rocks from the McArthur River area were used to determine the paragenetic sequence and origin of minerals in and near the fractures. Our work sought to determine if the host minerals record elements associated with the uranium deposit at depth and if they could be used to guide exploration (vectoring). Fracture orientations indicate that most are moderately dipping (<50°) and provided permeable pathways for fluid movement within the basin, from below, and through the overlying sedimentary rocks. Many of the fractures and adjacent wall rocks record evidence of multiple distinct fluid events. Seven types of fracture fillings were identified from drill core intersecting the Athabasca Basin and present distinct colors, mineralogy, and chemical features. Brown (Type 1) and pink (Type 7) fractures host paragenetically late botryoidal goethite, Mn oxide minerals, and poorly crystallized kaolinite that formed from relatively recent low-temperature meteoric fluids, as indicated by poor crystallinity and low δ2H values of –198 to –115‰. These minerals variably replaced higher temperature minerals that are rarely preserved on the fractures or in wall rock near the fractures. Hydrothermal alteration associated with the mineralizing system at ca. 200 °C is recorded in assemblages of dickite, well-crystallized kaolinite, and spherulitic dravite in some white and yellow (Type 2) and white (Type 3) fractures, as reflected by the crystal habits and variable δ2H values of –85 to –44‰. Fibrous goethite in white and yellow (Type 2) and black and orange (Type 5) fractures and microfibrous Mn oxy-hydroxide minerals in black (Type 4) fractures also crystallized from hydrothermal fluids, but at temperatures less than 200 °C. White and yellow fractures (Type 2) containing fibrous goethite reflect fracture networks indicative of hydrothermal fluids associated with the mineralizing system during primary dispersion of pathfinder elements and therefore extend the deposit footprint. Brown (Type 1) and pink (Type 7) fractures have low δ2H values in botryoidal goethite and poorly crystallized kaolinite and are indicative of the movement of meteoric waters. Secondary dispersion of elements from the deposit to the surface on some fractures is evidence that fractures are pathways for element migration from the deposit to the surface, over distances exceeding ∼500 m.

Alteration mineralogy and pathfinder element inventory in the footprint of the McArthur River unconformity-related uranium deposit, Canada

ABSTRACTPathfinder elements associated with the exploration footprint of the McArthur River unconformity-related U deposit include U, radiogenic Pb, V, Ni, Co, Cu, Mo, As, Zn, and rare earth elements. In this study, the mineralogical and paragenetic context for their occurrence was established by integrating in situ mineral chemistry and laser ablation mass spectrometry chemical mapping of interstitial assemblages, detrital grains, and cements with whole-rock analyses of drill core samples from the diagenetically altered background and the hydrothermally altered sandstone host rocks. Diagenetically altered background sandstones contain a matrix assemblage of illite and dickite, with trace to minor aluminum-phosphate-sulfate (APS) minerals, apatite, and Fe-Ti oxide minerals. Aluminum-phosphate-sulfate minerals account for the majority of the Sr and light rare earth element concentrations, whereas early diagenetic apatite, monazite, and apatite inclusions in detrital quartz and detrital zircon contribute significant U and heavy rare earth elements to samples analyzed with an aggressive leach (partial digestion) such as aqua regia. Hydrothermally altered sandstone host rocks also contain variable assemblages of Al-Mg chlorite (sudoite), alkali-deficient tourmaline, APS minerals, kaolinite, illite, Fe-oxide, and sulfide minerals. Late pre-mineralization chlorite accounts for a significant portion of the observed Ni concentrations, whereas Co, Cu, Mo, and Zn occur predominantly in cryptic sub-micron sulfide and sulfarsenide inclusions within clay mineral aggregates and in association with Fe-Ti oxides. Elevated concentrations of U were observed in cryptic micro-inclusions associated with sulfides in quartz overgrowths, with Fe-Ti oxide micro-inclusions in kaolinite, and in post-mineralization Fe-oxide veins. The distribution of pathfinder elements throughout the deposit footprint appears to be less related to the primary dispersion of alteration minerals from the hydrothermal system than to the secondary dispersion of elements post-mineralization. Their occurrence throughout pre-, syn-, and post-mineralization assemblages further demonstrates the limitations to defining geochemical footprints from pathfinder element concentrations expressed in lithogeochemical data sets without structural, lithological, and mineralogical context.

Elucidating Pathfinding Elements from the Kubi Gold Mine in Ghana

X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) are applied to investigate the properties of fine-grained concentrates on artisanal, small-scale gold mining samples from the Kubi Gold Project of the Asante Gold Corporation near Dunwka-on-Offin in the Central Region of Ghana. Both techniques show that the Au-containing residual sediments are dominated by the host elements Fe, Ag, Al, N, O, Si, Hg, and Ti that either form alloys with gold or with inherent elements in the sediments. For comparison, a bulk nugget sample mainly consisting of Au forms an electrum, i.e., a solid solution with Ag. Untreated (impure) sediments, fine-grained Au concentrate, coarse-grained Au concentrate, and processed ore (Au bulk/nugget) samples were found to contain clusters of O, C, N, and Ag, with Au concentrations significantly lower than that of the related elements. This finding can be attributed to primary geochemical dispersion, which evolved from the crystallization of magma and hydrothermal liquids as well as the migration of metasomatic elements and the rapid rate of chemical weathering of lateralization in secondary processes. The results indicate that Si and Ag are strongly concomitant with Au because of their eutectic characteristics, while N, C, and O follow alongside because of their affinity to Si. These non-noble elements thus act as pathfinders for Au ores in the exploration area. This paper further discusses relationships between gold and sediments of auriferous lodes as key to determining indicator minerals of gold in mining sites.

Encapsulation of a highly hydrophilic drug in polymeric particles: A comparative study of batch and microfluidic processes

The objective of this work was to investigate the effect of microfluidics on the quality attributes of metformin hydrochloride-loaded poly lactic-co-glycolic acid polymeric particles (MFH-PLGA PPs) when compared to a traditional double emulsion batch method. The relationship of encapsulation and loading efficiencies, yield %, particle size, surface morphology, and release profile with process and formulation variables were determined using design of experiments (DoE). The effects of the dispersal method of the primary (sonication vs. vortex) or secondary emulsion (microfluidics vs. batch), polyvinyl alcohol concentration (PVA), and drug to polymer ratio were investigated. The PPs’ size was impacted by both the PVA concentration and the type of primary and secondary emulsion dispersion methods. Microfluidics significantly increased the PPs’ yield %, particle size, encapsulation, and loading efficiencies. The higher loaded microfluidic-based PPs had more burst release, following first-order release kinetics when compared to the lower loaded batch-based particles, which followed the Korsmeyer-Peppas model for release kinetics. Microfluidic-based PPs exhibited a smooth, porous, more uniform, and larger particle size with hollow structure than the batch-based PPs with a matrix-like structure. In conclusion, we have elucidated the effect of microfluidics on the quality attributes of MFH-PLGA PPs and their comparison to the traditional batch technique.

Geochemistry of fracture coatings in Athabasca Group sandstones as records of elemental dispersion from the McArthur River Uranium deposit

A mineralogical and geochemical study of minerals on seven types of fracture fillings from near and above the McArthur River unconformity-related uranium deposit has been carried out to determine if fracture filling materials and wall rocks record evidence of primary and secondary dispersion of elements from the deposit. This study shows that Pb extracted by weak acid leaching (2% HNO3) provides Pb-Pb model ages near 1100 Ma for fractures with any of the three REE patterns: 1) LREE-enriched patterns, 2) REE patterns that are concave and similar to uraninite in the deposit, and 3) fractures with flat REE patterns. The REE patterns and ages indicate the fractures are an open system to post-mineralization dispersion of radiogenic Pb from a U-rich source, with a major mobilization of Pb from the uranium deposit at ca. 1100 Ma.Brown (Type 1) fractures, which host Mn-Fe oxides and clay minerals, provide the best evidence of U mineralization through post-mineralization dispersion, containing elevated concentrations of pathfinder elements Co, Ba, Tl, Mn and radiogenic Pb near the surface and at depth. Post-mineralization dispersion is also observed within brown (Type 1) and pink (Type 7; clay minerals + hematite) fractures and wall rock, showing low 207Pb/206Pb values of 0.29–0.50 that were subsequently overprinted by fluids with more common Pb, as recorded in fractures with higher 207Pb/206Pb values of 0.51–0.84.Fracture fillings were analyzed by continuous leach inductively coupled plasma mass spectrometry (CL-ICP-MS) to determine the relationship between trace elements and elemental release from specific mineral phases. CL-ICP-MS results indicate that common Pb (with 207Pb/206Pb values > 0.7) and anomalous Co (360 ppm) and V (220 ppm) contents are resident in organic phases that are dissolved during the 10% H2O2 leach phase. CL-ICP-MS also indicates that radiogenic Pb, as well as Ni and V, are resident in clay minerals and Fe-Mn oxy-hydroxides that break down during leaching with 30% HNO3. Uranium contents are low in the leachate during release of Fe, Al, Mn, and Pb using the 10% and 30% HNO3 leaches, reflecting post-mineralization dispersion of radiogenic Pb, but not U. Thus, secondary dispersion of elements into fractures enhances the size of the deposit footprint, particularly in deep fractures near the P2 fault, but also in some fractures near the surface. The results of this study strongly suggest that fractures did indeed act as conduits for dispersion of elements from the deposit, reaching all the way from deposit to the surface, providing viable exploration targets for U mineralization in sedimentary basins.

Ablation resistance of tungsten carbide cermets under extreme conditions

A cobalt-free tungsten carbide cermet (WC-FeNi) has been subjected to oxyacetylene flame tests to simulate extreme operating conditions such as a worst-case fusion reactor accident. In such an accident, air-ingress to the reactor may impinge on components operating at surface temperatures in excess of 1000 °C, leading to tungsten oxide formation and its subsequent hazardous volatilisation. Here, the most challenging accident stage has been simulated, where the initial air-ingress could lead to extremely rapid air-flow rates. These conditions were simulated using an oxidising oxyacetylene flame. The separation between flame nozzle and sample was varied to permit peak surface temperatures of ~950–1400 °C. When the peak temperature was below 1300 °C, the cermet gained mass due to the dominance of oxide scale formation. Above 1300 °C, the samples transitioned into a mass loss regime. The mass loss regime was dominated by liquid-phase ablation of the scale rather than its volatilisation, which was confirmed by performing a systematic thermogravimetric kinetic analysis. The result was unexpected as in other candidate shielding materials, e.g. metallic tungsten, volatilisation is considered the primary dispersion mechanism. The unusual behaviour of the cermet scale is explained by its relatively low melting point and by the lower volatility of its FeWO4 scale compared to tungsten's WO3 scale. The substantially lower volatility of the WC cermet scale compared to metallic W scales indicates it may have a superior accident tolerance.

The JNK pathway represents a novel target in the treatment of rheumatoid arthritis through the suppression of MMP-3

Background and aimThe pathophysiology of rheumatoid arthritis (RA) is characterized by excess production of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) by neutrophils and macrophages in synovium. Additionally, these cytokines promote the production of reactive oxygen species (ROS), and increased production of matrix metalloproteinases (MMPs), including MMP-3, in synoviocytes that result in joint destruction. There is limited information on how proteolytic enzymes such as MMP-3 can be regulated. We evaluated the effect of the antioxidant N-acetylcysteine (NAC) on RA and identified the relationship between the c-Jun N terminal kinase (JNK) pathway and MMP-3. We hypothesized that elucidating this relationship would lead to novel therapeutic approaches to RA treatment and management.MethodsWe investigated the effect of administering a low dose (1000 μM or less) of an antioxidant (NAC) to human rheumatoid fibroblast-like synoviocytes (MH7A cells). We also investigated the response of antioxidant genes such as nuclear factor erythroid -derived 2-related factor 2 (Nrf2) and Sequestosome 1 (p62). The influence of MMP-3 expression on the JNK pathway leading to joint destruction and the mechanisms underlying this relationship were investigated through primary dispersion culture cells collected from the synovial membranes of RA patients, consisting of rheumatoid arthritis-fibroblast-like synoviocytes (RA-FLS).ResultsLow-dose NAC (1000 μM) increased the expression of Nrf2 and phospho-p62 in MH7A cells, activating antioxidant genes, suppressing the expression of MMP-3, and inhibiting the phosphorylation of JNK. ROS, MMP-3 expression, and IL-6 was suppressed by administering 30 μM of SP600125 (a JNK inhibitor) in MH7A cells. Furthermore, the administration of SP600125 (30 μM) to RA-FLS suppressed MMP-3.ConclusionsWe demonstrated the existence of an MMP-3 suppression mechanism that utilizes the JNK pathway in RA-FLS. We consider that the JNK pathway could be a target for future RA therapies.

Advances in the use of isotopes in geochemical exploration: instrumentation and applications in understanding geochemical processes

Among the emerging techniques to detect the real footprint of buried ore deposits is isotope tracing. Novel and automated preparation systems such as continuous flow isotope ratio mass spectrometry, off-axis integrated cavity output spectroscopy for isotopic compositions of selected molecules, multi-collector inductively coupled-plasma mass spectrometry (ICP-MS), triple quadrupole ICP-MS, laser ablation ICP-MS, and a multitude of inline preparation systems have facilitated the use of isotopes as tracers in mineral exploration, as costs for isotope analyses have decreased and the time required for the analyses has improved. In addition, the isotope systems being used have expanded beyond the traditional light stable and Pb isotopes to include a multitude of elements that behave differently during processes that promote the mobilization of elements during both primary and secondary dispersion. Isotopes are also being used to understand barren areas that lack a critical process to form an ore deposit and to reveal precise redox mechanisms. The goal is to be able to use isotopes to reflect a definitive process that occurs in association with the deposit and not in barren systems, and then to relate these to something that is easier to measure, namely elemental concentrations. As new generations of exploration and environmental scientists are becoming more comfortable with the application of isotopes to effectively trace processes involved in geoscience, and new technologies for rapid and inexpensive analyses of isotopes are continually being developed, novel applications of isotope tracing are becoming more mainstream. Thematic collection: This article is part of the Exploration 17 collection available at: https://www.lyellcollection.org/cc/exploration-17

Минеральные ассоциации золоторудных проявлений Берентальского рудного поля (Северо-Восток России)

Berental prospective ore cluster (Magadan region) hosts a many ore occurrences, which differ in mineral composition, ore productivity, features of secondary and primary dispersion halos. As a result of the study of ores, mineral associations have been characterized, the stages of formation of ore occurrences and the alteration of the ore cluster have been established. The interrelation of five genetic types of native gold with mineral associations is revealed. Key ore occurrences have formed during several stages of ore formation associated with the evolution of a common hydro-thermal system. The earliest mineral association (arsenopyrite-lellingite), which contains the first generation of gold, was formed in the quartz-sericite facies in marginal parts of Berental stock and refers to the lower level of erosion truncation. After that, arsenopyrite-telluride association was formed in the marginal granites and arsenopyrite-galenobismutite association was formed in the exomorfic zone, they contain gold of the second - fourth generations with signs of recrystallization and diffusion transformations. Arsenopyrite-silver and pyrite-silver ore associations are localized at the upper level of the erosion trancation in calcium-containing birch with quartz veins, these associations contain low-fineness gold of the fourth and fifth generations. Pay gold mineralization of the Berental ore field is associated with arsenopyrite-telluride and arsenopyrite-galenobismutite associations, contains gold with a fineness of 750-945 %. The spatial placement of mineral associations is consistent with the placement of secondary and prima-ry scattering halos: complex Au-Bi-As halos accompany arsenopyrite-lellingite, arsenopyrite-telluride and arsenopy-rite-galenobismutite associations; for Au-As-Ag and Au-Ag-Pb-Zn association there is a spatial conjugation with ar-senopyrite-silver and pyrite-silver associations, respectively.

ПЕРСПЕКТИВИ ВІДКЛАДІВ НАДЗАПЛАВНИХ ТЕРАС ДНІСТРА НА ЗОЛОТУ МІНЕРАЛІЗАЦІЮ

The article clarifies the stratigraphic binding and origin of silicon nodules, which served as the main raw material for the manufacture of tools for mammoth hunters of the Mezhyrich Late Paleolithic site. In archaeological publications, these nodules are often mentioned to be confined to the "Vyrzhikovsky layer" (the Albian layer of the Lower Cretaceous), which was formed under continental conditions and consists of sand-clay (kaolin, in particular) deposits. The analysis of the necessary conditions and possible mechanisms for the formation of silicon nodules indicates the erroneousness of such ideas. Most likely, the source of silicon raw materials was the marine deposits of the Cenomanian (Upper Cretaceous), or, in accordance with the modern stratigraphic division of the Mesozoic-Cenozoic sequence, deposits of the Burim suite (upper Albian – lower Cenomanian). The paleogeographic setting, sedimentological conditions and lithological composition of the "Vyrzhikovsky layer" did not ensure the formation of silicon nodules in it in the form of inclusions. The latter are diagenetic in origin and could only form in the thickness of carbonate rocks, free of clay minerals. The region of Kaniv dislocations was the optimal region from the silicon production point of view, which was determined: firstly, by the tectonic dislocation of the sedimentary sequence, which contributed to the removal of deposits containing silicon nodules in the thickness of younger rocks; secondly,the erosion activity of temporary streams, which brought these deposits to the level of the denudation cut-off. The most convenient place for collecting flints was not the outcrop of bedrock in ravines but the cones of their removal, which overlook the floodplains of the Dnipro and Ros'. The possibility of collecting flint in the immediate vicinity of the Mezhirich site, in the ravines and gullies between the Ros and Rosava rivers, does not find confirmation, since the chalk deposits here lie much lower than the local erosion base and are not exposed by ravines. Therefore, the leading role in the formation of the raw material supply of the Late Paleolithic site of Mezhirich was played by the region adjacent to the Kaniv mountains of the alluvial-proluvial plain.Despite long-term geological study of the Dniester River basin, we still have no clear evidences about gold-bearing potentiality of this area as well as origin of gold. The leading role of geological, geochemical and mineralogical criteria is proved for defining the prospects of substantial gold deposits finding within the Dniester river basin. Gold was found here in the crystalline basement and in the sedimentary cover rocks. Study of mineralogy and lithology of the terraces above the flood-plain and typomorphic peculiarities of native gold shows that palaeogeographic conditions and alimentation zones of debris vary at the different tectonic stages of this area development. Gold-bearing potential of the Pliocene-Quaternary sediments in the Dniester River basin is related to the Pliocene (VI-IX terraces above the flood-plain) and Quaternary (I-V terraces above the flood-plain) terraces complex of the Dniester river, as well as this river and its inflows recent alluvia. Our study of the Mid-flow part of the Dniester river basin allow to conclude that native gold was found in geologocal strata of all ages, from Proterozoic up to the recent alluvium. This fact points the necessity of further prospecting to find the mother lodes of gold. Our field study, samples analyses made as well as publications observation allow highlighting the principal directions of further prospecting and evaluation works. The main among that are: 1) comprehensive study of river Dniester alluvia and its terraces complex (previously VI–VII terraces), that will allow to specify their material composition, to assess real gold-bearing potential and to define the history of denudation areas changes; 2) lithogeochemical prospecting of primary and secondary dispersion haloes to clear the principal gold-bearing regularities; 3) definition of prospect plots within the area described; 4) modern analytical approach study of typomorphic peculiarities of native gold from alluvia and terrace deposits to define its ore formational affinity and mineral type.