Decay Of Radioactive Elements Research Articles

Composites with Synergistically Enhanced Thermodynamic and Mechanical Properties for Geothermal Heat Exchangers

Geothermal energy, derived from the radioactive decay of elements within the Earth's core, is a renewable and clean energy source. The extraction of geothermal energy primarily depends on ground heat exchangers. To address the issue of incompatibility between corrosion resistance, high thermal conductivity, and mechanical performance in current ground heat exchangers, this study develops composites (PEPOE/SCA@SiC) composed of high‐density polyethylene (HDPE) modified with toughener polyethylene‐octene copolymer elastomer (POE) and silicon carbide (SiC) crystals modified with γ‐aminopropyltriethoxysilane (SCA). HDPE offers excellent corrosion resistance, SiC crystals provide efficient phonon transport, and SCA improves the interface compatibility of the composite. The thermal conductivity of PEPOE/SCA@SiC reaches 3.83 W m−1K−1, with a maximum tensile strength of 20.3 MPa, a tensile elastic modulus of up to 498 MPa, and a maximum bending stress of 22.2 MPa with a bending elastic modulus of 561 MPa. Corrosion resistance tests indicate no signs of corrosion in PEPOE/SCA@SiC when exposed to geothermal simulation fluids at 90 °C for 30 days. This study demonstrates that PEPOE/SCA@SiC composites have substantial potential for application in ground heat exchangers, offering promising prospects for advancing sustainable use of geothermal energy and environmental protection.

Discovery of the first olivine-dominated A-type asteroid family

The classical theory of differentiation states that due to the heat generated by the decay of radioactive elements, some asteroids form an iron core, an olivine-rich mantle, and a crust. The collisional breakup of these differentiated bodies is expected to lead to exposed mantle fragments, creating families of newly-formed asteroids. Among these new objects, some are expected to show an olivine-rich composition in spectroscopic observations. However, several years of spectrophotometric surveys have led to the conclusion that olivine-rich asteroids are rare in the asteroid main belt, and no significant concentration of olivine-rich bodies in any asteroid family has been detected to date. Using ESA’s Gaia DR3 reflectance spectra, we show that the family (36256) 1999 XT17 presents a prominence of objects that are likely to present an olivine-rich composition (A-type spectroscopic class). If S-complex asteroids as the second most prominent spectroscopic class in the family are real family members, then arguably the 1999 XT17 family has originated from the break-up of a partially differentiated parent body. Alternatively, if the S-complex asteroids are interlopers, then the 1999 XT17 family could have originated from the breakup of an olivine-rich body. This body could have been part of the mantle of a differentiated planetesimal, which may have broken up in a different region of the Solar System, and one of its fragments (i.e. the parent body of the 1999 XT17 family) could have been dynamically implanted in the main belt.

Weak Interaction and Radioactivity

The property of radioactivity was discovered in 1896 by the French physicist A. Becquerel. Further research showed that during the radioactive decay of elements, α-, β- and γ-rays are emitted. α-rays are helium nuclei, β-rays are electrons, γ-rays are electromagnetic waves.

Detection of Heat Resulting from Determining the Concentrations of some Radionuclides for Different Samples of Natural Water in Nineveh Governorate, Iraq

The current study included the determination of the Heat Production Rate (HPR) resulting from the decay of radioactive elements (238U, 232Th, and 40k) after determining their concentrations using the technique of collecting gamma ray’s spectrum by means of the sodium iodide detector NaI (TI). The importance of determining the heat production rate, because it has a profound effect on the surface of the earth’s crust, especially in the conditions of desertification that have swept the globe in the last two decades. To achieve the objective of the study, 30 samples of natural water were collected. These samples varied between rainwater, dams, groundwater and pure tap water to natural spring water. The results showed that the concentrations of uranium (238U) ranged between 0.161-0.006 ppm and thorium (232Th) concentrations between (0.462-0.110 ppm), in addition to the potassium (40k) concentration between (0.23-0.023%). These values showed radioactivity levels below the safe and standard limits set by the UNSCEAR Committee. While the results showed for the heat production rate values ranged between (0.0223-0.0091), which indicates a low heat production rate that does not affect the temperature of the earth's crust within the limits of the sample sites that this study included. The results of the current study can be used to provide basic data for future epidemiological investigations and monitoring programs. In the areas under study.

Relationship between radiogenic heat production in granitic rocks and emplacement age

Granites play a crucial role in the Earth's thermal regime and its evolution. Radiogenic heat production (RHP) by the decay of radioactive elements (U, Th, K) in granites is a significant parameter in estimating the thermal structure of the lithosphere. RHP variability of granites with their emplacement ages could provide insights for thermal modeling in different geological epochs. An aggregated RHP from 2877 globally-distributed granitic samples of continental crust are analyzed for this study; these sample cover the entire geological history. The average bulk RHP in all types of granitic rocks of all ages is 2.92 ± 1.86 μW/m3. The RHP tends to increase gradually with progressively younger geologic emplacement age, based on a statistical analysis of the data. However, the youngest granites do not necessarily have the highest RHP. The mean RHP in 181 representative Cenozoic Himalayan leucogranites— which are the youngest granites found on Earth, is as low as 1.84 μW/m3. This is probably related to the initial conditions of magma formation, magmatic source material, and differentiation processes in the Himalayan–Tibetan plateau. By correcting the decay factor, variations of the RHP in the emplaced granitic rocks are obtained, indicating the changing levels of heat production and different thermal regimes on Earth in various geological epochs. The highest RHP in granitic rocks emplaced in the Archean and Early Proterozoic corresponds to two global-scale collisional events during supercontinent cycles, at 2.7 and 1.9 Ga respectively. RHPs of granites can be an important indicator in the study of Earth's thermal regime and its evolution.

The Influence of the Radiation Background of City-Forming Settlements with NPPs on Public Health and the Environment

The radioactive decay of elements as a result of a nuclear reaction is a powerful source of energy used in the production of electricity and heat in cities close to NPPs. The problem of using this kind of energy is the danger of radiation exposure. The production of nuclear energy has many advantages, including the profitability of the final product and its low cost; on the other hand, the half-life products of radionuclides in the composition of gas-aerosol emissions from ventilation pipes settle in the environment on the territory of city-forming nuclear power plants. The duality of the problems of the impact of radiation background on the urban areas near NPPs has become the purpose of this study. It is necessary to investigate the negative effect of radioactive waste emissions during the normal operation of nuclear power plants. For this purpose, the method of a project experiment was used, during which, using laboratory monitoring of external radiation safety and an automated radiation monitoring system, indicators of exposure dose capacities were collected from points in the 30-kilometre zone around the NPP. As a result of the monitoring of radiation samples from soil, atmospheric air and precipitation, and reservoirs, it was revealed that the natural radiation background is insignificant; the probability of harm from radiation exposure is small and insufficient for the development of radiation sickness. However, potentially unsafe sources of radiation exposure have been identified, such as natural radiation – the consumption of contaminated food, solar and cosmic radiation from radioactive elements present in the bowels of the earth; radionuclides, whose emissions uncontrollably occur into the atmosphere; radioactive waste, the disposal and storage technology of which is economically costly. Therefore, it is justified to conduct regular design experiments to check the operability of automated radiation monitoring systems. The materials of the study are of practical value for chemists, environmentalists, and ecotechnologists working at NPPs that monitor safety for human health and environmental protection in the field of atomic energy use

Ultrahigh temperature metamorphism recorded in the Lüliang Complex, Trans-North China Orogen: P–T–t evolution and heating mechanism

Identifying ultrahigh temperature (UHT) metamorphism from hot orogens and establishing its pressure–temperature–time (P–T–t) path will provide notable insights into tectonic evolution and heat source (mantle/mafic magma vs crustal radioactive elements) responsible for the extreme conditions. We report here a combined investigation of petrography, mineral chemistry, phase equilibria modelling, geothermobarometer calculation, geochronology and heat source for mafic and pelitic granulites from the Lüliang Complex, Trans-North China Orogen (TNCO), a representative Paleoproterozoic hot collisional orogen. The rocks record clockwise P–T paths, including granulite-facies peak and post-peak retrograde stages. Garnet + pyroxene + high-Ti hornblende-bearing assemblage in the mafic granulite and garnet + feldspar + sillimanite-bearing assemblage in the pelitic granulite constrain the thermal peaks at 8.2–10 kbar and 880–959 °C, suggesting UHT conditions. Zircon and monazite U–Pb dating, hornblende 40Ar/39Ar dating and Ti-in-zircon thermometer calculation indicate that the rocks may have experienced sluggish retrograde metamorphism from 1.92 to 1.80 Ga, with a cooling rate of 2.0–2.5 °C/Ma. The newly discovered UHT metamorphism, combined with previous geological data, validates a long-lived tectono-thermal evolution from 1.97 to 1.80 Ga in the TNCO. The calculated heat flow produced by the decay of radioactive elements in the thickened crust is 37–77 mW/m2 (with an average of 56 mW/m2), which is high enough to achieve UHT conditions. Therefore, we suggest that radioactive heating can be an important heating mechanism for UHT metamorphism in a long-lived hot orogen like the TNCO.

Paleowind Directions over the Tarim Block during the Mesoproterozoic, Northwestern China

The Tarim Block is an ancient plate with a basement of ancient continental crust, which has been separated from the Rodinia supercontinent since the Neoproterozoic. During the Neoproterozoic, which lasted nearly 500 Myr, this block experienced significant evolutionary processes, such as proliferation, radioactive decay of elements, and gradual cooling and solidification. The investigation of Neoproterozoic paleogeography may shed light on the evolution of these geological events. In order to realize this potential, this study aimed to infer paleowind directions over the Tarim Block during each epoch of the Cryogenian–Ediacaran and to constrain the paleogeographic location of the Tarim Block. To this end, outcrop magnetic fabric data were employed to analyze the anisotropy of magnetic susceptibility within the Tarim Block. The anisotropy of magnetic susceptibility measurements yielded mean paleowind directions of 308° ± 69°, 277° ± 78°, and 256° ± 76° from the present north for the Early, Middle, and Late Cryogenian, respectively; the corresponding values for the Early and Late Ediacaran were 237° ± 77° and 254° ± 73° from the present north, respectively. Considering the rotation relationship of the Tarim Block from the Neoproterozoic to the present, the paleowind directions during the Early, Middle, and Late Cryogenian were ~55°, ~35°, and ~35° from the paleo-north, respectively. The paleowind directions during the Early and Late Ediacaran were ~35° and ~60° from paleo-north, respectively. By referring to the correspondence between the paleowind directions over the Tarim Block and trade winds in the Northern Hemisphere, this study provides evidence for the location of the Tarim Block during the Cryogenian–Ediacaran. The main contributions of this study can be summarized as follows: (1) paleowind patterns are established through the analysis of the anisotropy of magnetic susceptibility; (2) the paleogeographic location of the Tarim Block during the Cryogenian–Ediacaran is constrained; and (3) a reference for further study of the paleogeography of the Tarim Block during the Cryogenian–Ediacaran is provided.

The Impacts on Consumer Health from Dug Well Contamination - A Crucial Drinking Water Source

Abstract: Main objective of this review is to analyse potential sources of pollution, constituents, consumer health risks related to contaminated drinking water, and remediation strategies. Dug wells with poorly protected well mouth-covering or unlined wells are more susceptible to biological and chemical contamination. Physical irregularities in the lining and covering of the well act as a door to the entry of pollutants into the well. Residential, municipal, commercial, industrial, and agricultural activities can have an impact on ground water quality. Agriculture is one of the most common human activities that have an impact on both surface and groundwater. Water resource quality is determined by geological characteristics such as soil kinds, topography slope, plant roots, water dissolution with minerals/soils, and the radioactive decay of elements. Septic tanks, pit latrines, and sewer systems are the main source of faecal contamination in the groundwater system. Pesticides, fertilisers, and livestock dung frequently introduce heavy metals into aquifers, posing a direct hazard to human health. Waterborne diseases such as diarrhoea, cholera, syphilis, and typhoid have been linked to a lack of adequate water. Drinking water containing various anions and heavy metals, such as Cd, Cr, Co, Hg, Ni, Pb, Zn, and others, has a substantial negative impact on human health. Drinking water treatment removes impurities from the source water, making it safe to drink. The long-term goal of decontamination is to detect and remove hazardous compounds from water cost-effectively and reliably.

Mantle Degassing Lifetimes through Galactic Time and the Maximum Age Stagnant-lid Rocky Exoplanets Can Support Temperate Climates

The ideal exoplanets to search for life are those within a star’s habitable zone. However, even within the habitable zone, planets can still develop uninhabitable climate states. Sustaining a temperate climate over geologic (∼gigayear) timescales requires a planet to contain sufficient internal energy to power a planetary-scale carbon cycle. A major component of a rocky planet’s energy budget is the heat produced by the decay of radioactive elements, especially 40K, 232Th, 235U, and 238U. As the planet ages and these elements decay, this radiogenic energy source dwindles. Here we estimate the probability distribution of the amount of these heat-producing elements that enter into rocky exoplanets through Galactic history by combining the system-to-system variation seen in stellar abundance data with the results from Galactic chemical evolution models. From this, we perform Monte Carlo thermal evolution models that maximize the mantle cooling rate, thus allowing us to create a pessimistic estimate of lifetime a rocky, stagnant-lid exoplanet can support a global carbon cycle through Galactic history. We apply this framework to a sample of 17 likely rocky exoplanets with measured ages, seven of which we predict are likely to be actively degassing today, despite our pessimistic assumptions. For the remaining planets, including those orbiting TRAPPIST-1, we cannot confidently assume that they currently contain sufficient internal heat to support mantle degassing at a rate sufficient to sustain a global carbon cycle or temperate climate without additional tidal heating or undergoing plate tectonics.

The Planetary Vaporization Event Hypothesis: Supercharging Earth’s Geothermal Core, Identifying Side Effects Blast Patterns, and Inferring how to Find Earth-Like Planets or Identifying Super Charged Geothermal Cores and their Byproduct Blast Patterns

The supercharged nature of the Earth’s geothermal core can be demonstrated by three thought experiments exhibiting it is tremendously more powerful than any other terrestrial object in the solar system (planet or moon). Identifying a minimum of four byproduct asteroid blast patterns linked to the formation of Earth’s supercharged geothermal core is critical to properly identifying stars that also have these four byproduct asteroid blast patterns. These stars are the most likely to host an Earth-like planet qualified by having a supercharged geothermal core. The Planetary Vaporization-Event (PVE) Hypothesis provides a basis for correlation between the supercharged nature of Earth’s geothermal core and at least 14 listed side effects: (1) the asteroid-wide/planet-scale homogenization and lack thereof of 182W ε for Earth, the Moon, Mars and meteors, (2) the primary and secondary shifting of Earth’s tectonic plates, (3) the solar system wide displacement of Earth’s wayward moons (including Ceres, Pluto, Charon and Orcus) outgassing identical samples of ammoniated phyllosilicates, (4) the formation of asteroids at 100+ times the expected density of a nebular cloud vs. pre-solar grains formation density at the expected density of a nebular cloud, (5) three distinct formation timestamps for all known asteroids within a 5 million year window 4.55+ billion years ago, (6) the estimated formation temperature of CAI at 0.86 billion Kelvin and (7) the remaining chondritic meteorite matrix flash vaporizing at 1,200–1,900 °C, (8) followed by rapid freezing near 0 K, (9) the development of exactly 2 asteroid belts and a swarm of non-moon satellites, (10) particulate size distinction between the 2 asteroid belts of small/inner, large/outer, (11) the proximity of the Trojan Asteroid Groups to the Main Asteroid Belt, (12) observation of a past or present LHB, (13) the development of annual meteor showers for Earth proximal to apogee and/or perigee, (14) the Sun being the most-likely object struck by an asteroid in the inner solar system. Through better understanding of the relevant data at hand and reclassification of the byproducts of supercharging the core of a planet, at least 5 new insights can be inferred and are listed as: (1) the original mass, (2) distance and (3) speed of Earth Mark One, (4) the original order of Earth’s multi-moon formation and (5) the high probability of finding detectable signs of life on a planet orbiting the stars Epsilon Eridani and Eta Corvi. There are at least 6 popular hypothesis that the PVE Hypothesis is in conflict with, listed they are: (1) a giant impact forming the Moon, (2) asteroids being the building blocks of the solar system, (3) the Main Asteroid Belt being the result of a planet that never formed, (4) the LHB being a part of the accretion disk process, (5) the heat in Earth’s core coming primarily from the decay of radioactive elements, (6) the Oort Cloud being the source of ice comets.

The Planetary Vaporization Event Hypothesis: Supercharging Earth’s Geothermal Core, Identifying Side Effects Blast Patterns, and Inferring how to Find Earth-Like Planets or Identifying Super Charged Geothermal Cores and their Byproduct Blast Patterns

The supercharged nature of the Earth’s geothermal core can be demonstrated by three thought experiments exhibiting it is tremendously more powerful than any other terrestrial object in the solar system (planet or moon). Identifying a minimum of four byproduct asteroid blast patterns linked to the formation of Earth’s supercharged geothermal core is critical to properly identifying stars that also have these four byproduct asteroid blast patterns. These stars are the most likely to host an Earth-like planet qualified by having a supercharged geothermal core. The Planetary Vaporization-Event (PVE) Hypothesis provides a basis for correlation between the supercharged nature of Earth’s geothermal core and at least 14 listed side effects: (1) the asteroid-wide/planet-scale homogenization and lack thereof of 182W ε for Earth, the Moon, Mars and meteors, (2) the primary and secondary shifting of Earth’s tectonic plates, (3) the solar system wide displacement of Earth’s wayward moons (including Ceres, Pluto, Charon and Orcus) outgassing identical samples of ammoniated phyllosilicates, (4) the formation of asteroids at 100+ times the expected density of a nebular cloud vs. pre-solar grains formation density at the expected density of a nebular cloud, (5) three distinct formation timestamps for all known asteroids within a 5 million year window 4.55+ billion years ago, (6) the estimated formation temperature of CAI at 0.86 billion Kelvin and (7) the remaining chondritic meteorite matrix flash vaporizing at 1,200–1,900 °C, (8) followed by rapid freezing near 0 K, (9) the development of exactly 2 asteroid belts and a swarm of non-moon satellites, (10) particulate size distinction between the 2 asteroid belts of small/inner, large/outer, (11) the proximity of the Trojan Asteroid Groups to the Main Asteroid Belt, (12) observation of a past or present LHB, (13) the development of annual meteor showers for Earth proximal to apogee and/or perigee, (14) the Sun being the most-likely object struck by an asteroid in the inner solar system. Through better understanding of the relevant data at hand and reclassification of the byproducts of supercharging the core of a planet, at least 5 new insights can be inferred and are listed as: (1) the original mass, (2) distance and (3) speed of Earth Mark One, (4) the original order of Earth’s multi-moon formation and (5) the high probability of finding detectable signs of life on a planet orbiting the stars Epsilon Eridani and Eta Corvi. There are at least 6 popular hypothesis that the PVE Hypothesis is in conflict with, listed they are: (1) a giant impact forming the Moon, (2) asteroids being the building blocks of the solar system, (3) the Main Asteroid Belt being the result of a planet that never formed, (4) the LHB being a part of the accretion disk process, (5) the heat in Earth’s core coming primarily from the decay of radioactive elements, (6) the Oort Cloud being the source of ice comets.

Lithospheric electrical structure beneath the Cathaysia Block in South China and its tectonic implications

To better constrain the heat source of the geothermal system and lithospheric thinning mechanism of the Paleo-Pacific subduction zone, data from 35 broadband magnetotelluric (MT) stations were collected in 2020 along a 180-km-long NW-trending profile in the Cathaysia Block. Based on the measured data, we obtained the lithospheric electrical structure of the Cathaysia Block in South China using the 3D MT inversion code of ModEM. The final resistivity structure along the profile shows a series of highly conductive anomalies and highly resistive anomalies. The highly resistive anomalies in the upper crust correspond well with the distribution of magmatic rocks, which extend downwards to depths of 20 km. The highly resistive anomalies with a depth of 20–40 km are interpreted as crustal mafic sills derived from the mantle. The crustal conductors at depths of 5–15 km are typically interpreted as accumulations of aqueous fluids, which originate from the dehydration of the slab during the flat-slab subduction of the Paleo-Pacific Plate and are confined in the crust by impermeable layers. Fluid fractions of 0.8–9% would be required to explain the observed conductance values. The MT results indicate that there is no magma chamber or partial melt beneath the geothermal system. Therefore, the heat source of the geothermal system in the Cathaysia Block is radiogenic heat produced by the decay of radioactive elements in the crust. Thermal erosion has played a central role in lithospheric thinning and crust–mantle interaction of the Cathaysia Block.

The Origin of the Late-time Luminosity of Supernova 2011dh

Abstract Due to the small amount of hydrogen (≤0.1 M ⊙) remaining on the surface of their progenitors, SNe IIb are sensitive probes of the mass-loss processes of massive stars toward the ends of their lives, including the role of binarity. We report late-time Hubble Space Telescope observations of SN 2011dh in M51, and a brief period of rebrightening and plateau in the photometric light curve, from 1.8 to 6.2 yr after the explosion. These observations exclude the role of circumstellar interaction, however, a slow rotating magnetar, a significant quantity of radioactive elements, or a light echo could be responsible for the late-time luminosity observed at t > 1000 days. If the late-time light curve is powered by the decay of radioactive elements, SN 2011dh is required to have produced ∼2.6 × 10−3 M ⊙ of 44Ti, which is significantly in excess of the amount inferred from earlier nebular spectra of SN 2011dh itself or measured in the Cas A SN remnant. The evolution of the brightness and the color of the late-time light curve also supports the role of a light echo originating from dust with a preferred geometry of a disk of extent ∼1.8 to ∼2.7 pc from the SN, consistent with a wind-blown bubble. Accounting for the long-term photometric evolution due to a light echo, the flux contribution from a surviving binary companion at ultraviolet wavelengths can be isolated and corresponds to a star of ∼9–10 M ⊙.

GIS Analysis and Evaluation on the Geothermal Reserves of the Coastal Area of Jeju Island and Ulleung Island, Volcanic Islands in South Korea

Kim, H.C.; Baek, S.K., and Hwang, J.H., 2019. GIS analysis and evaluation on the geothermal reserves of the costal area of Jeju island and Ulleung island, volcanic islands in South Korea. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Remote Sensing and Geoscience Information Systems of Coastal Environments. Journal of Coastal Research, Special Issue No. 90, pp. 377-385. Coconut Creek (Florida), ISSN 0749-0208.South Korea has the greatest growth in greenhouse gas (GHG) emissions among Organization for Economic Cooperation and Development countries. To reduce emissions through voluntary GHG reduction measures, at the 21st Summit of the Conference on Climate Change in France, geothermal energy was selected as a key technology for the achievement of 50 % reduction in national GHG emissions by 2020. To meet this challenge, selection of the most suitable (reasonable and efficient) geothermal energy development site is necessary. The development of economical geothermal power through the efficient execution of the state budget for future geothermal energy development is also necessary. In other countries, geothermal power is being developed using the heat around active volcanoes. In Korea, geothermal abnormalities are related mostly to the geothermal heat produced by the radioactive decay of elements. The research area selected for this study comprised Korea's representative volcanic islands, Jeju Island and Ulleung Island. The geothermal investigation on Jeju Island was assessed through several boreholes, revealing generally lesser heat flow than that of inland of South Korea. On the other hand, a high temperature gradient was found through recent drilling on Ulleung Island. To determine the cause of this high gradient, rock thermal properties and borehole irradiation data from the coastal areas of Jeju and Ulleung islands were compared. It need to be calculated the geothermal reserve and constructed geothermal parameter maps of the volcanic Jeju and Ulleung islands in South Korea for regional analysis and evaluation. As a result, the average thermal conductivity of rocks is 1.69 W/mK (Ulleung) and 1.76 W/mK (Jeju), lower than inland. In the case of geothermal gradient, heat flow, and heat production rate, Ulleung island is average 86.55 °C/km, 127.06 mW/m2, 3.75 µW/m3 and Jeju island is average 24.65 °C/km, 40.13 mW/m2, 0.76 µWm3. It is the value significantly higher Ulleung island than inland, but Jeju island is lower than inland. It seems to be the reason related to the occurrence origin of the volcanic island.

Geochemical and Isotopic Compositions and Geothermometry of Thermal Waters in the Magumsan Area, South Korea

The Magumsan thermal waters of the southeastern Korean Peninsula are pumped out of six deep wells (average depth, 300 m) at temperatures of 30.8–49 °C. The thermal waters are chemically classified into two groups: NaHCO3 type (<31 °C) and NaCl (HCO3, SO4) type (>40 °C), both of which have chemical compositions that are distinct from local groundwater (Ca–HCO3 type). δ18O and δD values suggest that the thermal waters originate from meteoric water and they are isotopically fractionated by silicate hydration or H2S exchange. δ34S values (+7.0 to +15%) of dissolved sulfate in the thermal waters reflect enrichment in 34S through kinetically controlled oxidation of magmatic pyrite in the thermal aquifer and mixing with paleo-seawater. On the 3He/4He vs. 4He/20Ne diagram, the thermal waters plot along a single air mixing line of dominant crustal He, which indicates that the heat source for the thermal waters is non-volcanogenic thermal energy that is generated from the decay of radioactive elements in crustal rocks. Chalcedony geothermometry and thermodynamic equilibrium calculations using the PHREEQC program indicate a reservoir temperature for the immature thermal waters of 54–86 °C and 55–83 °C, respectively.

Comparison on Rare Gas Geochemical Characteristics and Gas Originations of Kuche and Southwestern Depressions in Tarim Basin, China

The Kuche Depression is considered as the most important gas resource potential and gas exploring area with great gas resource potential and prospect in the Tarim Basin. Based on geochemical experimental analyses and comprehensive geological studies, the general geochemical characteristics of molecular and isotope compositions of rare gases as well as hydrocarbon gases and nonhydrocarbon gases are comparatively studied in the Kuche and Southwestern Depressions. Then, their genetic types are separately identified and gas originations are comprehensively discussed. The main results are as follows. (1) Gas fields in the Kuche Depression have a higher methane abundance, accompanied with low N2and CO2abundances, but the Akemomu gas field in the Southwestern Depression has a relatively lower average methane abundance, accompanied with high average N2and CO2abundances. The helium abundance of natural gases in gas fields from the Kuche Depression general has 1 order of magnitude higher than the air value. Comparatively, it has more than 2 orders of magnitude higher than the atmospheric value in the Akemomu gas field from the Southwestern Depression. The neon, argon, krypton, and xenon abundances in both Kuche and Southwestern Depressions are lower than the corresponding air values. (2) Natural gases from gas fields in the Kuche Depression and the Southwestern Depressions are generally typical coal-formed gases. The rare gases in the Kuche Depression have typical crustal genesis, mainly deriving from the radioactive decay of elements in the crust, while in the Akemomu gas field from the Southwestern Depression, the rare gases have main crustal genesis with a proportion of 92.5%, probably accompanied with a little mantled genetic contribution. (3) Natural gases in the Kuche Depression are generally derived from coal measure source rocks of Jurassic and Triassic, which principally originated from Jurassic in strata period and coals in source rock types. The Jurassic source rocks account for 55%-75% and the Triassic source rocks account for 25%-45% approximately, while coals occupy 68% and mudstones occupy 32% separately. Natural gases from the Akemomu gas field in the Southwestern Depression mainly originated from humic mudstones of marine and continental transitional source rocks of Carboniferous to Permian.

A fast-evolving luminous transient discovered by K2/Kepler

For decades optical time-domain searches have been tuned to find ordinary supernovae, which rise and fall in brightness over a period of weeks. Recently, supernova searches have improved their cadences and a handful of fast-evolving luminous transients (FELTs) have been identified. FELTs have peak luminosities comparable to Type Ia supernovae, but rise to maximum in $<10$ days and fade from view in $<$month. Here we present the most extreme example of this class thus far, KSN2015K, with a rise time of only 2.2 days and a time above half-maximum ($t_{1/2}$) of only 6.8 days. Here we show that, unlike Type Ia supernovae, the light curve of KSN2015K was not powered by the decay of radioactive elements. We further argue that it is unlikely that it was powered by continuing energy deposition from a central remnant (a magnetar or black hole). Using numerical radiation hydrodynamical models, we show that the light curve of KSN2015K is well fit by a model where the supernova runs into external material presumably expelled in a pre-supernova mass loss episode. The rapid rise of KSN2015K therefore probes the venting of photons when a hypersonic shock wave breaks out of a dense extended medium.

The nature of gamma-ray bursts in the framework of the byuon theory

Two models of gamma-ray bursts using the theory of byuons (TB) are considered. This theory describes a “life’ of special unobservable discrete objects from which the surrounding space and the world of ultimate particles are formed. Basic axioms and some conclusions of this theory are discussed. The results of experimental investigations of new non-gauge interaction (using high current magnets, torsion and piezo resonance balances, and changes in the rate of β - decay of radioactive elements etc.) are described. It is shown that basic problems with nature of gamma-ray bursts can be solved in the framework of this theory not only for bursts connected with supernova explosions but also for those without explosions. The conditions for ejection of matter during a SN explosion due to the non-gauge force action are shown.

Sulfur mass-independent fractionation in subsurface fracture waters indicates a long-standing sulfur cycle in Precambrian rocks

The discovery of hydrogen-rich waters preserved below the Earth's surface in Precambrian rocks worldwide expands our understanding of the habitability of the terrestrial subsurface. Many deep microbial ecosystems in these waters survive by coupling hydrogen oxidation to sulfate reduction. Hydrogen originates from water–rock reactions including serpentinization and radiolytic decomposition of water induced by decay of radioactive elements in the host rocks. The origin of dissolved sulfate, however, remains unknown. Here we report, from anoxic saline fracture waters ∼2.4 km below surface in the Canadian Shield, a sulfur mass-independent fractionation signal in dissolved sulfate. We demonstrate that this sulfate most likely originates from oxidation of sulfide minerals in the Archaean host rocks through the action of dissolved oxidants (for example, HO· and H2O2) themselves derived from radiolysis of water, thereby providing a coherent long-term mechanism capable of supplying both an essential electron donor (H2) and a complementary acceptor (sulfate) for the deep biosphere.