A new potentially large uranium district in Russia (Far East)

Research subject. The aim was to justify the prospects of uranium deposits in the Tyrminsk area of the Far East, which were briefly studied over 60 years ago. These deposits are highly similar to those located in the Streltsovsk mega uranium district. Materials and methods. The materials were geological data on uranium deposits in the promising Tyrminsk district and in the largest Streltsovsky district in the Far East. The research method was a comparison of the available information about the geological features of uranium deposits and ore areas as a whole. Results. The uranium ore regions under study are localized in Mesozoic volcanogenic calderas, within Paleozoic granites. Specific uranium deposits are formed at intersections of multidirectional faults, most frequently in the vicinity of volcanic caldera boundaries. The deposits formed within a contrasting geological section are represented by steep vein-like and stock-like bodies, as well as by gently sloping formation-like bodies under the screens of layers of dense sandstones and siltstones. In addition, deposits are found in favourable layers of conglomerates and effusives breccia. The length and thickness of ore bodies comprise 0.2–1 km and 1–80 m, respectively. Uranium ores belong to the fluorine-molybdenum-uranium type; near-ore rocks are represented by mudstones and hydrosludites. Some fields in the Tyrminsk district are opened by wells to a depth of 80– 160 m from the surface, while the fields in the Streltsovsk district are explored by wells and underground mine workings to a depth of 1.5 km from the surface. Conclusion. The extent of uranium deposits in the Tyrminsk district is predicted to reach a depth of 500–700 m, with their resources being estimated as “large” based on the high similarity of localities in the areas under study. As the most promising uranium area in the south Far East, the Tyrminsk district is recommended as a priority exploration site for uranium.

Morphology, taxonomy and distribution of the rare species Aulacoseira cataractarum (Hustedt) Simonsen (Bacillariophyta) in Russia

This scanning electron microscopy study was undertaken to reanalyze frustule samples of the centric diatom algae Aulacoseira cataractarum, collected earlier from a swamp in the Uzon volcanic caldera (Kamchatka). This species, under the name of Melosira cataractarum, was reported before from a number of waterbodies in Russia. Later it was transferred to the genus Aulacoseira Thwaites – A. cataractarum (Hustedt) Simonsen (Simonsen, 1979), and then – to the genus Pseudostaurosira (A.Grunow) D.M.Williams & F.E.Round, under the name of P. seudostaurosira cataractarum (Hustedt) Wetzel, Morales et Ector. In this study we specify perforation of intercalary bands, the shape of the valves and spines as well as the number of valve face and mantle areolae per stria and their shape. Based on the original and published data an extended diagnosis of P. cataractarum is presented. Scanning electron microscope images of frustules of the centric diatom algae.

Variability of Carbonate Isotope Signatures in a Hydrothermally Influenced System: Insights from the Pastos Grandes Caldera (Bolivia)

Laguna Pastos Grandes (Bolivia), nesting in a volcanic caldera, is a large, palustrine-to-lacustrine system fed by meteoric and hydrothermal calco–carbonic fluids. These different fluid inputs favor a complex mosaic of depositional environments, including hydrothermal springs, pools, and an ephemeral lake, producing abundant present-day carbonates developing over a Holocene carbonate crust dated by U–Th. Present-day carbonates (muds, concretions, and microbialites) recorded a large range of isotope variations, reaching 13.9‰ in δ13C and 11.1‰ in δ18O. Sedimentological and geochemical data indicated that the main processes influencing the isotope record were: (i) rapid CO2 degassing and temperature decreases along hydrothermal discharges; (ii) strong evaporation favored by the arid high-altitude Andean climate, locally enhanced by capillary water rise within microbial mats or by wind-induced spray falling on vadose concretions. Unlike past or present perennial lake systems in Central Andes, the short residence time of brine waters in the ephemeral central lake prevents enrichment of lacustrine carbonates in 13C and 18O. The very low fraction modern F14C in these present-day carbonates demonstrates that incorporation of fossil magmatic carbon related to the volcanic context also prevents any radiocarbon dating. The use of isotopes for the interpretation of ancient continental series should always be accompanied by a thorough characterization of the environmental setting.

Responses of Ground-Dwelling Spider (Arachnida: Araneae) Communities to Wildfire in Three Habitats in Northern New Mexico, USA, with Notes on Mites and Harvestmen (Arachnida: Acari, Opiliones)

Catastrophic wildfire is increasingly common in forests of the western United States because climate change is increasing ambient temperatures and periods of drought. In 2011, the Las Conchas wildfire burned in the Santa Fe National Forest of New Mexico, including portions of ponderosa pine and mixed-conifer forests, and grasslands in the Valles Caldera National Preserve, a large, high-elevation volcanic caldera. Following the fire, Caldera staff began monitoring abiotic, plant, and animal responses. In this study, ground-dwelling arachnids were collected in pitfall traps in burned and unburned habitats from 2011–2015. Permutational multivariate analysis of variance (PERMANOVA) mostly at the genus level with some higher taxon levels showed significant fire, year, and interaction effects. Abundance was at or near unburned levels by 2014, but species composition changed in burned areas. Pardosa and Haplodrassus were dominant genera across habitats. Linyphiids were strong indicators of unburned sites. Harvestmen were among the dominant species in the forest habitats, and erythraeid mites were abundant in the burned ponderosa pine forest and the grassland. Years were not significantly autocorrelated, unsurprising given the interannual variation in precipitation in this generally arid region. Although fire is a common feature of these habitats, future fires may be outside of historical patterns, preventing spider communities from re-establishing fully.

Genetic polymorphism in populations of voles and shrews from the Kronotsky Reserve (Kamchatka Peninsula, Russia)

We studied genetic polymorphism of four mammal species Myodes rutilus, Myodes rufocanus, Sorex isodon, from four localities, the Valley of Geysers, Uzon volcanic caldera, the Death Valley, and the Shore of Kuril Lake. In total, 172 individuals were genotyped using the inter-simple sequence repeat technique. We observed the lowest polymorphism in shrews S. caecutiens. In this species, 68.8 % of bands were polymorphic, and Nei’s genetic diversity (h) was 0.27, while these values in S. isodon were 81.3 % and 0.29, respectively. Populations of M. rufocanus were the most polymorphic among the studied species (P = 91.4, h = 0.34). Polymorphism in M. rutilus from Kamchatka (P = 87.2, h = 0.29) was similar to that from Western Siberia. In addition, we found a high genetic differentiation of rodent populations. The interpopulation component of genetic variability was about 30–40 % (GST = 0.31 in M. rutilus and 0.39 in M. rufocanus). Gene flow among populations of M. rutilus from Kamchatka was two times lower than that of populations of the species from taiga ecosystems in Siberia. Key words: Myodes, Sorex, Differentiation of populations, Genetic variability, ISSR markers, Kamchatka Peninsula

Genetic polymorphism in populations of voles and shrews from the Kronotsky Reserve (Kamchatka Peninsula, Russia)

We studied genetic polymorphism of four mammal species Myodes rutilus, Myodes rufocanus, Sorex isodon, from four localities, the Valley of Geysers, Uzon volcanic caldera, the Death Valley, and the Shore of Kuril Lake. In total, 172 individuals were genotyped using the inter-simple sequence repeat technique. We observed the lowest polymorphism in shrews S. caecutiens. In this species, 68.8 % of bands were polymorphic, and Nei’s genetic diversity (h) was 0.27, while these values in S. isodon were 81.3 % and 0.29, respectively. Populations of M. rufocanus were the most polymorphic among the studied species (P = 91.4, h = 0.34). Polymorphism in M. rutilus from Kamchatka (P = 87.2, h = 0.29) was similar to that from Western Siberia. In addition, we found a high genetic differentiation of rodent populations. The interpopulation component of genetic variability was about 30–40 % (GST = 0.31 in M. rutilus and 0.39 in M. rufocanus). Gene flow among populations of M. rutilus from Kamchatka was two times lower than that of populations of the species from taiga ecosystems in Siberia. Key words: Myodes, Sorex, Differentiation of populations, Genetic variability, ISSR markers, Kamchatka Peninsula

The Seismic Network of Zapopan: Evaluating the local seismicity of the western Guadalajara Metropolitan Zone

<p>The Municipality of Zapopan, Jalisco, is located west of the Guadalajara Metropolitan Zone at the intersection of three rift zones: Tepic-Zacoalco, Chapala-Tula, and Colima. The importance of this region lies in the recent population growth that it has experienced in a few years. This growth has been supported by the development in commercial and service activities, and mainly in industry and technology, being ranked as the second-most populous city in Mexico, behind the federal capital.</p><p>The western region of the Guadalajara Metropolitan Zone (GMZ) has numerous fault systems where, historically, there have been significant earthquakes and seismic swarms such as those that occurred in 1685-1687, 1875, 1932, 1995 and 2002, showing similar characteristics. Besides, it is in this region where the Caldera de la Primavera is located, a rhyolitic volcanic caldera that continues presenting seismic and geothermal activity.</p><p>Recently, in the years 2015 and 2016, new seismic swarms occurred and were recorded instrumentally for the first time by the Jalisco Seismic and Accelerometric Network (RESAJ). The two seismic sequences took place in two alignments in the same direction as the Colima rift. These epicenters suggest the existence of two almost parallel normal faults, and that would be forming the Graben of Zapopan. Due to the length of these faults, 16 km for the east fault, and 28 km for the west fault, earthquakes of magnitudes 6.2 - 6.5 could be generated.</p><p>In the framework of the CeMIEGeo P-24 project (SENER-CONACyT), we continue studying the seismicity of this region with the deployment of 25 seismic stations in the vicinity of La Caldera de la Primavera. This study revealed the high seismicity that was taking place in the area of ​​Zapopan, Tesistán Valley, and La Caldera de la Primavera.</p><p>Based on these new studies and the knowledge of the seismic history of the region, a collaboration agreement has been established between the Research Group UDG-CA-276 SisVOc and Civil Protection of the Municipality of Zapopan for the installation of a local seismic network that will allow to define tectonic and structurally the fault systems of the region and mitigate the possible effects of the local seismicity in the population. Since May 2019, three Obsidian 8X seismic stations with Lennartz 1Hz LE3D and Episensor sensors and two accelerometers installed in the city have been operating, constituting the Zapopan Seismic and Accelerometric Network (RESAZ). The RESAZ operates together with the nearest stations of the RESAJ. In this work, we present the first results of the seismicity analysis recorded in Zapopan.</p>

Distribution of major and trace elements in bottom sediments of the Taquari River Basin, Caldas municipality (Brazil)

The Taquari River Basin, located in Poços de Caldas Alkaline Complex, in the southern portion of Minas Gerais state, Brazil, is situated in an old volcanic caldera. Due to its chemical and radiological characteristics, it is an area of economic and mineral interest, and is also home to diverse flora and fauna systems. In its surroundings, there are agricultural areas, industries (active and inactive) and urban and rural centers. This work investigated the total and potentially bioavailable concentrations of major and trace elements for the evaluation of geogenic and anthropogenic contamination potentials in the water bodies. The results show that there is an anthropogenic contribution (fertilizers and mining tailings) in some sectors of the Taquari River Basin, generating possible concerns regarding the quantity of elements that may be transferred to the water bodies. Furthermore, there is the striking geogenic contribution from naturally enriched areas, presenting distinct situations that generate an increase in the concentration of chemical elements in the water bodies.