Search

The paper deals with investigations of equation of motion for magnetic fluids, consisting of nano-particles or holding definite nano-particle inclusions. The equation is received by means of application the laws of conservation for linear and angular momentums. In low magnetic fields fluids are unable to reach saturation and nanoparticles revolve in additional rotating magnetic field. The magnetization in magnetic fluids increases in spiral form. [ABSTRACT FROM AUTHOR]

The article introduces six articles on fluid inclusions in ore deposits, including fluid inclusions in opaque ore minerals by Kalin Kouzmanov et al., the solubility data for the H20-NaC1-LiCl ternary system by Michael Dubois et al., and the geochemical and isotopic properties of fluids from gold-bearing and barren quartz veins of the Sovetskoye Gold Deposit in Siberia by A. Tomilenko et al.

Replacement Style Mineralizations. The paper presents occurrence and chemistry of ore and gangue minerals, results of fluid inclusion microthermometry and sulfur isotopes, and discussed the evolution of mineralizing fluids. The polymetallic mineralization was divided into two stages; the early Cu-Zn-(Pb) and late Cu-Zn-Pb-(Mn) mineralization stages, which are associated with a granodioritic porphyry stock and quartz porphyry sills, respectively. [Extracted from the article]

Our recent paper (Nishiyama et al. in Earth Planets Space 73:126, 2021) suggested that the sealing time of a crack-seal event recorded in quartz-filled shear veins in the Makimine mélange may temporally increase or decrease. Nishiyama et al. (Earth Planets Space 73:126, 2021) describes the optical estimates of the vapor–liquid ratio of primary two-phase fluid inclusions between solid inclusion bands in shear veins. The variation in vapor–liquid ratio was used as an indicator of fluid pressure conditions at the time of trapping of fluid inclusions during a crack-seal event. Comment on our paper (Williams in Earth Plantes Space 10.1186/s40623-022-01599-1 2023) raised the issue that our paper neglected the error in fluid pressure associated with the uncertainties in the optical estimate of the vapor–liquid ratio of fluid inclusions. Williams (Earth Plantes Space 2023 10.1186/s40623-022-01599-1) claimed that, if a certain uncertainty in the optical estimate of the vapor–liquid ratio is considered, there is a large error in the fluid pressure. The argument by Williams (Earth Plantes Space 2023 10.1186/s40623-022-01599-1) is based on the assumption that the uncertainty of the vapor–liquid ratio can be determined accurately. An accurate estimate of the uncertainty of the vapor–liquid ratio is possible if the homogenization temperature of the fluid inclusion is measured. However, it has been a challenging issue to measure the homogenization temperature of fluid inclusions between inclusion bands in a crack-seal vein, because the spacing of inclusion bands is too small (typically, a few tens of microns or less) to measure the homogenization temperature. Therefore, it is difficult to provide a confidential discussion regarding the error in the fluid pressure during a crack-seal event. Nishiyama et al. (Earth Planets 73:126, 2021) showed the sealing time of a crack-seal vein for a wide range of fluid pressure drops and discussed that the sealing time is comparable to the slow slip and tremor recurrence intervals when the fluid pressure drop is large. We consider that such a presentation and discussion are appropriate rather than discussing the error in fluid pressure based on the ambiguous uncertainty in the optical vapor–liquid ratio estimate. [ABSTRACT FROM AUTHOR]

The characteristics and stages of collapse-filling in paleo-underground rivers vary in recharge-runoff-discharge zones, constraining the associated fracture-caved reservoirs in carbonate strata. This paper comprehensively uses core, fluid inclusion, and carbon-oxygen isotope to probe the evolution process and migration of collapse-filling in paleo-underground rivers in the Northern Uplift of the Tarim Basin. The results show that 1) more than three stages of collapse-filling were identified in recharge-runoff-discharge zones, and a four-stage differential collapse-filling process was proposed to summarize the evolution of paleo-underground rivers. 2) The collapse-filling process varies spatiotemporally in the recharge, runoff, and discharge zones. Hydrodynamic strength and filling capacity migrate gradually from the recharge zone to the discharge zone. 3) Collapse-filling mechanisms, including gravity, suffusion, and suction-erosion mechanisms, also vary along with the collapse-filling evolution process of paleo-underground rivers. The research provided a new insight to recognize and interpret the differential planar distribution and vertical filling of the paleo-underground river system, which can be further applied to investigate the fracture-caved karst reservoirs. [ABSTRACT FROM AUTHOR]

The Shimensi super-large tungsten polymetallic deposit is located in the Late Jurassic–Early Cretaceous Porphyry–Skarn tungsten ore belt in the south Yangtze metallogenic belt. There are three types of mineralization: veinlet-disseminated type, thick quartz vein type and hydrothermal cryptoexplosive breccia type. Based on geological studies, this paper presents new petrographic, microthermometric, laser Raman spectroscopic and hydrogen and oxygen isotope research on the fluid inclusions from the deposit. The results show that there are five different types of fluid inclusions: liquid-rich inclusions, vapor-rich inclusions, pure liquid inclusions, pure vapor inclusions, and fluid inclusions containing a solid crystal. The homogenization temperatures of the fluid inclusion range from 140 °C to 270 °C, the salinities are 3 wt.%–5 wt.% NaCleq and the densities of ore-forming fluid range from 0.64 g/cm3 to 0.99 g/cm3. For the analyses of laser Raman spectroscopy, the ore-forming fluids can be approximated by a Ca2+-Na+-SO42−-Cl− fluid system with small amounts of CO2, CH4 and N2. Otherwise, the data of the pressure, pH and Eh show a fluid metallogenic environment of low pressure, weak acid and weak reduction. The values of the homogenization temperature in the three types of orebodies suggest that the mineralization is characterized by a decrease in temperature under the conditions of fluid immiscibility. The H-O isotope values are interpreted to indicate that the ore-forming fluids are mainly composed of magmatic water, and meteoric water is added with the process of magma rising. [ABSTRACT FROM AUTHOR]

Biomolecular condensates are crucial compartments within cells, relying on their material properties for function. They form and persist through weak, transient interactions, often undetectable by classical biochemical approaches. Hence, microscopy-based techniques have been the most reliable methods to detail the molecular mechanisms controlling their formation, material properties, and alterations, including dissolution or phase transitions due to cellular manipulation and disease, and to search for novel therapeutic strategies targeting biomolecular condensates. However, technical challenges in microscopy-based analysis persist. This paper discusses imaging, data acquisition, and analytical methodologies' advantages, challenges, and limitations in determining biophysical parameters explaining biomolecular condensate formation, dissolution, and phase transitions. In addition, we mention how machine learning is increasingly important for efficient image analysis, teaching programs what a condensate should resemble, aiding in the correlation and interpretation of information from diverse data sources. Influenza A virus forms liquid viral inclusions in the infected cell cytosol that serve as model biomolecular condensates for this study. Our previous work showcased the possibility of hardening these liquid inclusions, potentially leading to novel antiviral strategies. This was established using a framework involving live cell imaging to measure dynamics, internal rearrangement capacity, coalescence, and relaxation time. Additionally, we integrated thermodynamic characteristics by analysing fixed images through Z-projections. The aforementioned paper laid the foundation for this subsequent technical paper, which explores how different modalities in data acquisition and processing impact the robustness of results to detect bona fide phase transitions by measuring thermodynamic traits in fixed cells. Using solely this approach would greatly simplify screening pipelines. For this, we tested how single focal plane images, Z-projections, or volumetric analyses of images stained with antibodies or live tagged proteins altered the quantification of thermodynamic measurements. Customizing methodologies for different biomolecular condensates through advanced bioimaging significantly contributes to biological research and potential therapeutic advancements. [ABSTRACT FROM AUTHOR]

A recent paper by Nishiyama et al. (Earth, Planets, and Space 73:126) examined syntectonic quartz veins to constrain temporal variations in the recurrence intervals between slow slip and tremor events. The authors claim that by examining the liquid-volume fraction of syntectonic fluid inclusions in the veins, that they can accurately reconstruct pore-fluid pressures (and variations therein) that were operative during faulting at ~ 15 km depth in an exhumed subduction melange. From these observations, the authors infer that large (from lithostatic to hydrostatic) decreases in pore-fluid pressure occurred during faulting, and that these variations drove increases in supersaturation and rapid quartz precipitation over time scales consistent with the repeat times of seismologically observed slow slip and tremor events. Here, I show that Nishiyama et al.'s analysis neglects reasonable uncertainties in pore-fluid pressure reconstruction. When those uncertainties are included, the Nishiyama et al.'s results become ambiguous as to whether any variation in pore-fluid pressure during vein formation occurred at all, negating the validity of many of the subsequent conclusions. [ABSTRACT FROM AUTHOR]

Whether from the near-surface or at great depths, geothermal energy aims to harness the heat of the Earth to produce energy. Herein, emphasis is put on geothermal reservoirs and their cap rock in crystalline rocks, in particular, the basements of sedimentary basins and volcanic islands in the context of subduction. This study is based on a case study of three examples from around the world. The aim of this paper is to show how the study of newly formed minerals can help the exploration of geothermal reservoirs. The key parameters to define are the temperature (maximum temperature reached formerly), fluid pathways, and the duration of geothermal events. To define these parameters, numerous methods are used, including optical and electronic microscopy, X-ray diffraction, microthermometry on fluid inclusions, chlorite geothermometry, and geochemistry analysis, including that of isotopes. The key minerals that are studied herein are phyllosilicates and, in particular, clay minerals, quartz, and carbonates. They are formed because of hydrothermal alterations in fracture networks. These minerals can have temperatures of up to 300 °C (and they can cool down to 50 °C), and sometimes, they allow for one to estimate the cooling rate (e.g., 150 °C/200 ka). The duration of a hydrothermal event (e.g., at least 63 Ma or 650 ka, depending on the site) can also be established based on phyllosilicates. [ABSTRACT FROM AUTHOR]

The article offers information on the study conducted by the authors related to the analysis of the conceptual model of hydrothermal activity at Yucca Mountain, Nevada by the U.S. Department of Energy (DOE). It states that a unique conceptual model envisaging conductive heating of rocks in the thick unsaturated zone of Yucca Mountain by a silicic pluton was emplaced, with an explanation of the elevated depositional temperatures measured in fluid inclusions in secondary fluorite and calcite.

The study of fluid inclusions in petroliferous basins is an effective method to understand hydrocarbon migration and accumulation. In this paper, the fluid inclusions in the Ordovician carbonate rock samples taken from the TS3, TP18, YQ8 and YJ2-3 wells in Tahe Oilfield are analyzed by experiments, the purpose is to explore the accumulation period of the Ordovician oil and gas reservoirs in the Tahe area and the reasons for the differences between different blocks.The results show that the Ordovician Yingshan Formation and the Yifangfang Formation in the Tahe area are rich in fluid inclusions, and there are only a single phase of oil, gas and brine in the phase. There are also two phases of oil, gas and water mixed with each other. According to the fluorescence characteristics and homogenization temperature of hydrocarbon inclusions, combined with the burial history-thermal evolution history of the study area, it is determined that the Tahe oil and gas reservoir is filled in the fourth stage, in the middle of the Caledonian period (454-446 Ma), and in the late Hercynian-Indosinian period (255-217 Ma), late Yanshanian period(143-99 Ma), Himalayan period (25-5 Ma).Among them, the middle of Caledon is mainly filled with low-mature oil, with a small amount of mature oil; the late high-mature oil in the late Hercynian is filled with some mature oil; the late Yanshan is mainly filled with high mature oil; during the Himalayan period, as the depth of burial continues to increase, the cracking of the accumulated hydrocarbons has occurred, mainly the migration of gas hydrocarbons. The four wells selected in this study belong to different tectonic units, after analysis, the author believes that the difference between single wells is on the one hand the influence of hydrocarbon thermal evolution and the other is influenced by tectonic movement. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present paper considers petrographic and geochemical features of rocks of the Tigrinoe and Zabytoe stocks, provides their mineral composition, the results of the detailed study of micas and mineral-forming inclusions in quartz. It is shown that the development of ore-magmatic systems (OMSs) of the Zabytoe and Tigrinoe deposits is associated with the same rare-metal Li–F melts. It is confirmed that granitoids of the Tigrinoe stock can be considered as more differentiated analogs of granitoids of the Zabytoe stock. New data concerning the differences in the history of the magmatic stage of development of the OMSs of these deposits are presented. The evolution of melts of both deposits took place at high fluid pressure. Differences in the scale of ore mineralization of the two RMSs under consideration could be due to different fluid regime of magmatic sources evolution and more significant participation of transmagmatic fluid flows in the development of the Tigrinoe OMS. [ABSTRACT FROM AUTHOR]

Topaz is a kind of mineral with variable composition and a common gemstone variety. Because of its wide distribution and rich colors, it has attracted the attention of scholars around the world. In this paper, the composition, spectral, and gemological characteristics of yellow topaz were systematically characterized, and the dark inclusions inside the samples were discussed and analyzed. The results show that the yellow topaz has a glassy luster, transparent, with a refractive index of 1.609–1.617 and a birefringence of 0.008. The topaz sample has columnar crystal shape and a typical rhomboid cross section. The infrared spectral characteristic absorption peaks of yellow topaz mainly appear near 3649, 3426, 950, 628, 550, and 457 cm−1. The characteristic absorption peaks for Raman spectra are mainly at 937, 404, and 267 cm−1. The UV-vis spectra of all samples only had strong absorption bands in the range of 200–300 nm. The results of XRF and EMPA showed that the contents of Al2O3 and SiO2 in the samples were 52.79 (wt%) and 29.55 (wt%), respectively, and it was reasonable to speculate that the chromogenic element of the yellow color was iron. The inclusions in yellow topaz samples are mainly fluid inclusions, healing cracks, and albite. This paper has enriched the gemological characteristics of topaz and can provide theoretical data for the research and marketization of topaz. [ABSTRACT FROM AUTHOR]

This paper presents the derivation of the homogenized equations that describe the macroscopic mechanical response of elastomers filled with liquid inclusions in the setting of small quasistatic deformations. The derivation is carried out for materials with periodic microstructure by means of a two-scale asymptotic analysis. The focus is on the non-dissipative case when the elastomer is an elastic solid, the liquid making up the inclusions is an elastic fluid, the interfaces separating the solid elastomer from the liquid inclusions are elastic interfaces featuring an initial surface tension, and the inclusions are initially n -spherical (n = 2 , 3 ) in shape. Remarkably, in spite of the presence of local residual stresses within the inclusions due to an initial surface tension at the interfaces, the macroscopic response of such filled elastomers turns out to be that of a linear elastic solid that is free of residual stresses and hence one that is simply characterized by an effective modulus of elasticity L ‾ . What is more, in spite of the fact that the local moduli of elasticity in the bulk and the interfaces do not possess minor symmetries (due to the presence of residual stresses and the initial surface tension at the interfaces), the resulting effective modulus of elasticity L ‾ does possess the standard minor symmetries of a conventional linear elastic solid, that is, L ‾ i j k l = L ‾ j i k l = L ‾ i j l k . As an illustrative application, numerical results are worked out and analyzed for the effective modulus of elasticity of isotropic suspensions of incompressible liquid 2-spherical inclusions of monodisperse size embedded in an isotropic incompressible elastomer. [ABSTRACT FROM AUTHOR]

Copyright of Oltenia, Studii si Comunicari Seria Stiintele Naturii is the property of Museum of Oltenia Craiova and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Increasing applications of transcatheter aortic valve replacement (TAVR) to treat high- or medium-risk patients with aortic diseases have been proposed in recent years. Despite its increasing use, many influential factors are still to be understood. Furthermore, innovative applications of TAVR such as in bicuspid aortic valves or in low-risk patients are emerging in clinical use. Numerical analyses are increasingly used to reproduce clinical treatments. The future trends in this area are foreseen for in silico trials and personalized medicine. Areas covered: This review paper analyzes the recent years (Jan 2018 – Aug 2020) of in silico studies simulating the behavior of transcatheter aortic valves with emphasis on the addressed clinical question and the used modeling strategies. The manuscripts are firstly classified based on their clinical hypothesis. A second classification is based on the adopted modeling approach in terms of patient domain, device modeling, and inclusion or exclusion of the fluid domain. Expert opinion: The TAVR can be virtually performed in numerous vessel geometries and with different devices. This versatility allows a rapid evaluation of the feasibility of different implantation approaches for specific patients, and patient populations, resulting in faster and safer introduction or optimization of new treatments or devices. [ABSTRACT FROM AUTHOR]

The Tuotuohe region is a highly prospective area for Pb and Zn mineral exploration. This paper contributes to our comprehension of the ore-controlling structures, fluid inclusions, and C–H–O–S–Pb isotope geochemistry of Pb–Zn deposits in this region. These deposits are generally hosted by carbonates and controlled by fractures. The principal homogenization temperatures of quart- and calcite-hosted inclusions ranged predominantly between 120 and 220 °C, with salinities varying from 6 to 16 wt.% NaCl equivalent. The Pb isotope compositions of the ore deposits are comparable to those of Cenozoic volcanic rocks in the region but differ significantly from those of the host rocks, indicating that the Pb within these deposits was derived from the mantle. The C, O, and S isotope compositions of samples exhibit a bimodal distribution based on whether they were derived from magma or host rocks, implying that magma-derived fluids underwent an isotopic exchange with the host rocks. The H-O isotope compositions of samples also indicate that ore-forming fluids were originally magmatic but were depleted by combining with meteoric water. These findings are also supported by variations in fluid inclusion homogenization temperatures and salinities. Taken together, these findings suggest that the Pb–Zn deposits of the Tuotuohe region developed from magma to hydrothermal fluids at medium–low temperatures. [ABSTRACT FROM AUTHOR]

Beyond recent related literature, which focused on spherical incompressible liquid inclusions, the present work studies an elliptical compressible liquid inclusion in an infinite elastic plane under static remote mechanical loading. Here, it is assumed that the change of pressure inside the liquid inclusion is linearly related to the change of inclusion volume with the bulk modulus of the liquid as the proportionality coefficient. Also, the role of the liquid surface tension on the solid-liquid interface is examined especially when the size of the liquid inclusion is comparable to or smaller than the elastocapillary length. Our results show that both the surface tension and the change of liquid pressure have a significant effect on reducing the stress concentration factor at the endpoints of an elliptical liquid inclusion. In addition, the pressure change inside the liquid inclusion is studied when a uniaxial remote stress is applied perpendicular or parallel to the major axis of the elliptical liquid inclusion. In particular, the effective plane-strain Young's modulus of a solid-liquid composite containing circular liquid inclusions predicted by the present model is linearly related to the volume fraction of the liquid inclusions, in reasonable agreement with existing experimental data. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of carbonate and sulfate–carbonate–clayey rocks of the Lower Maeotian in the sections of the bays of Cape Kazantip using a complex of analytical methods. It is established that the greatest variation of chemical, bituminological, phase, and carbon-isotope composition is characterized by carbonate–clay and clayey rocks of the section bottom. It is proved that the initial OM was accumulated mainly under reducing conditions, but has some variations in composition; it is characterized by a low degree of its catagenetic transformation, which indicates the preservation of the primary isotopic composition. The diverse phase composition of the clay fraction is revealed: dioctahedral illite, kaolinite, chlorite, glauconite, and weakly ordered mixed-layer formations of illite/smectite type with different ratios of illite and smectite components and varying degrees of ordering. Modeling of their diffraction profiles showed that the illite/smectite structure may indicate significant depths of sediment mobilization by mud volcanoes. The isotopic composition of the 13Сorg ranges widely from –33.72 to –19.27‰ the mode being –22.1...–24.93‰. The isotopic composition of 13Сorg below –25.6‰ may be related to the entry of isotope-light mass of methane-oxidizing bacteria into the OM. It was revealed that variations of isotopic composition curves 13Сcarb and 13Сorg along the section of the studied rocks are rarely characterized by unidirectional (positive or negative) variations and have different trends along the section. Direction of the 13Сcarb isotope composition curve with some variations has a pronounced upward trend toward heavier weighting, whereas the isotopic values of the 13Сorg reveals reverse tendency. The results obtained prove that the revealed variations in the composition of OM and carbon isotope composition in the Lower Maeotian sections of Cape Kazantip reflect variations in the sedimentation conditions of temperature, salinity, freshwater ingression, bioproductivity fluctuations, and the influence of local gas–fluid deposition. It is proposed to use such accessory minerals as zircon, monazite, and ilmenite as an indicator of mud paleovolcanism. [ABSTRACT FROM AUTHOR]

The paper presents data on quartz-hosted fluid inclusions in commercial ores of various type (veinlet−disseminated and vein) of the Verninskoe gold deposit. The ores of various types were found out to significantly vary in the values of some of their physicochemical parameters of the fluids and in the composition of these fluids. The fluids that formed the gold veins have a somewhat higher initial temperature (356–246°C), a higher density of carbon dioxide in gas inclusions (1.00–0.84 g/cm3), and a higher fluid pressure (3170–1390 bar) than those of the fluids that formed the veinlet–disseminated ores (330–252°C, 0.87–0.54 g/cm3, and 1960–570 bar, respectively). The fluids that formed the gold veins were enriched in CО2, Sr, Ag, Ga, Ge, Mn, Fe, Ni, Sn, Ba, and REE, whereas the fluids that formed veinlet–disseminated mineralization were richer in , Br, Sb, V, and Au. This situations may be explained by the interaction of the deep fluid with the terrigenous host rocks in the course of ore deposition. When vein quartz crystallized in relatively wide fractures, the fluid interacted with host rocks and changed not as much as when the veinlet−disseminated ores were formed in narrow fractures. The initial parameters of the fluid that formed the vein quartz were thus the closest to the characteristics of the fluid that transported the ore components, and the comparison of these data with the parameters of the fluids that formed the veinlet–disseminated mineralization demonstrates that they changed in the course of ore deposition. The mineral-forming fluids likely came from a deep-sitting source, and the mineral-forming processes may have involve granitoid-derived fluids. [ABSTRACT FROM AUTHOR]

This paper presents data on the geological position, geochemical features, main mineral composition (micas, feldspars), and melt and fluid inclusions in quartz from Aba high-silica leucocratic granitoids in the western part of the Talitsa batholith, Russian Altai. According to these new geochemical data, the granitoids are classified as S-type, meaning they are formed via the partial melting of metasedimentary source rocks. Geological data and oxygen isotope composition analysis indicate that major-phase granitoid magma evolution took place at the level of intrusion formation, whereas the parent melt of late-phase leucogranite evolved in a deeper chamber. The geochemical features (HFSE and REE, and REE spectra) of the granitoids indicate significantly higher differentiation in the late leucocratic phase. The presence of coexisting syngenetic melt and fluid inclusions shows that leucogranite magma was already saturated with volatiles in the early crystallization stages. Based on the new data presented in this work, the Aba rock formation is associated with the volatile saturation of magmatic melts, the exsolution of a fluid phase, and magma degassing. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the chemical composition (including H2O and CO2) of matrix glass, melt inclusions in phenocrysts, and their host minerals in eruptive products from Aso caldera. We found a group of melt inclusions with clearly lower potassium (0.6–2 wt % K2O at 50–70 wt % SiO2) than previously reported high-K2O whole-rock compositions (3–5 wt % K2O at 55–70 wt % SiO2). While most of the high-K2O intermediate to felsic melt inclusions are vapor undersaturated and show the features of H2O, CO2, and K2O accumulation, the low-K2O basaltic melt already has higher H2O and CO2. We reconcile this discrepancy with a model in which (1) the volatile-rich basalt magmas degas near the surface, (2) migrate back to depths of |$\ge$| 12 km in the crust, and (3) crystallize feldspar and quartz to produce high-K2O felsic melt, (4) magma mixing among the undegassed, degassed, and evolved magmas. By crystallization, about five times as much low-K2O basaltic magma is required to produce high-K2O felsic magma. The quantity of felsic magma ejected from 270 ka (Aso-1) to 90 ka (Aso-4) requires a basalt magma supply rate of 18 to 31 km3/ka. This magma supply rate is comparable to or less than the present-day production rate of degassed magma (73 km3/ka) at an active center of Aso, Nakadake. These findings suggest volcanic gas flux monitoring has the potential to be a 'basalt usage meter' during the dormant period of caldera volcanoes. [ABSTRACT FROM AUTHOR]

The study provides a detailed account of the evolution of different fluids during the diagenesis of the Upper Jurassic Barsarin Formation and how the fluids shifted from the original chemistry and affected the host carbonate rocks. Diagenesis includes all the biological, physical, chemical, biochemical, and physicochemical alterations that occur immediately after deposition and prior to low-grade metamorphism. Overall, diagenetic alterations are, directly or indirectly, driven and mediated by fluid flows in sedimentary basins that determine the porosity and permeability evolution of carbonate and sandstone reservoirs/aquifers. [Extracted from the article]

In the process of diagenesis and burial of sedimentary basins, basin fluid activities participate in the process of hydrocarbon accumulation and metal mineralization. Understanding the evolution of basin fluid is of great significance in revealing the related hydrocarbon accumulation and mineralization. Paleo-reservoirs are closely associated with Carlin-type gold deposits in the Nanpanjiang-Youjiang Basin, South China. Calcite, the fluid activity product, is closely related to bitumen and gold-bearing pyrite. By integrating petrographic, cathode luminescence, and fluid inclusion analysis, as well as the relevant chronological results of predecessors, this paper attempts to establish the relationship between fluid evolution, hydrocarbon accumulation, and gold mineralization. Two types of calcite (black/gray and white) developed in the Banqi-Yata-Laizishan area, the Nanpanjiang-Youjiang Basin. Black/gray calcite is symbiotic with bitumen and features dark red colors in cathode luminescence. Many hydrocarbon inclusions developed along with fluid inclusion analysis at low homogenization temperatures (65.7~173.1 °C). Combining the previously reported U-Pb ages (~250–230 Ma) of this kind of calcite with some geochemistry data on the associated reservoir and gold deposit, this calcite records the consecutive hydrocarbon accumulation and Carlin-type gold mineralization from the Late Permian to the Late Triassic periods controlled by Indosinian tectonic movement. The white calcite featuring bright red in cathodoluminescence is symbiotic with gold-bearing pyrite and realgar, and the associated fluid inclusions have high homogenization temperatures (128.2~299.9 °C). Combined with regional tectonic background and isotopic chronology (~140–106 Ma), it seems to record the early Cretaceous Carlin-type gold mineralization controlled by the subduction of the paleo-Pacific plate in the late Yanshanian period. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guilin University of Technology is the property of Journal of Guilin University of Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Fernando de Noronha archipelago (southwest Atlantic, 345 km from the coast of Brazil) is considered as the result of mantle plume activity. However, data on the isotopic composition of helium and neon, which are, perhaps, the only unambiguous geochemical criterion for deep mantle plumes have not been published yet for the region. In this paper, we present the first data on the isotopic composition of helium, neon, argon, and nitrogen, obtained by stepwise crushing of mantle xenoliths from the basanites of the San José Formation. The results obtained may indicate that fluid inclusions contain the very first portions of the exsolved gases—they are ultra-depleted in helium in relation to neon and especially argon. This conclusion is also supported by He–Ar–CO2 systematics. The isotopic composition of helium (4He/3He = 31 879 ± 6796) and neon (21Ne/22Ne(mantle) = 0.0453 ± 0.0012) indicates that it was indeed a mantle plume, identical in noble gas composition to the Kerguelen plume. According to the Ar–Ne isotope systematics 40Ar/36Ar (mantle) = 7455 ± 2290. Nitrogen is characterized by a heavy isotopic composition (δ15N = +5.4 ± 0.2‰), which corresponds to the hypothesis of the subduction nature of nitrogen in deep mantle plumes. [ABSTRACT FROM AUTHOR]

This paper discusses mineralogic and geochemical features of dominantly silver mineralization in secondary quartzites of the Kyplatap volcanic field (KVF) confined to the southeastern flank of the eponymous intrusive dome structure (IDS) that complicates the Palyavaam–Pykarvaam volcano-tectonic depression which is part of the Chaun zone of the Central Chukchi sector of the Okhotsk–Chukchi volcanogenic belt (OChVB). The Kyplatap IDS was formed as a large laccolite-like subvolcanic body intruded into the Alkakvun rhyolites and trachyrhyolites. The KVF contains an abundance of secondary quartzites that compose both linear zones along faults mostly northeast striking and fault-bounded isometric fields. Potential ore bodies are represented by linear zones of crushed and brecciated secondary quartzites accompanied by quartz veinlets and veins. The ore bodies are long up to 200 m and 2–5 m thick. Spotty, veinlet-impregnated, and brecciated structures predominate in the ore bodies. The ore mineralization is mostly impregnated, less frequently in veinlets. The main vein minerals are quartz (30–70%), hydromica (15–20%), sericite, kaolinite, adularia, ferrous carbonate, zircon, chlorite, and alunite. The main ore minerals are pyrite, arsenopyrite, acanthite, polybasite, pearceite, and native silver. The typomorphic feature of the mineralization is thin intergrowths of silver sulfosalts, native silver, and iron hydroxides. We note that dominantly silver mineralization in secondary quartzites within the OChVB was found for the first time ever. The results of surveys classify the Kyplatap ore occurrence as a gold-silver mineral type deposit (Au/Ag = 1 : 450 on average) of the selenium subtype because of considerable admixture of selenium in the ore minerals. The occurrence of Ag mineralization in secondary quartzites and mudstones may provide evidence that it belongs to the high-sulfidation epithermal class. These features of the KVF epithermal mineralization are largely similar to the formation of siliceous and quartz–alunite lithocaps that are formed above degassing intrusions. In such conditions, the HS-type ore-bearing fluids are either not formed in the system or did not reach the epithermal depths. The ore field is poorly or moderately eroded, what is indicated by a practically complete absence of minerals of the polymetallic association and by the dominance of acanthite and silver sulfosalts over native phases. [ABSTRACT FROM AUTHOR]