Volcanic emissions and the early Earth atmosphere

Despite uncertainties in our understanding of early Earth volcanism and atmospheric composition, thermodynamic modelling is able to offer estimates of the global production of reactive trace species (NO, OH, SO₃, Cl, Br and I) from early Earth volcanism, and thereby to shed light on processes which may have been different in Earth’s early atmosphere. Model results show that thermal decomposition of magmatic H₂O, CO₂ and SO₂ in high-T mixtures of magmatic and atmospheric gases (at T > 1400 °C) generate high levels of reactive trace gas species. Production of these reactive trace species is insensitive to atmospheric CO₂ in mixtures where the atmospheric gas is the minor component and will hence continue during periods of low atmospheric CO₂. Fluxes of NO, OH, Cl, Br and I from early Earth volcanism are predicted to exceed those from modern Earth volcanism as the higher temperature of early Earth emissions compensates for lower levels of O₂ in the atmosphere, compared to the modern Earth. Under certain conditions, the volcanic NO flux from early Earth volcanism is found to be comparable to other sources of reactive N such as lightning NO and photochemical HCN. This is one possible source of fixed nitrogen which may alleviate any postulated Archean nitrogen crisis. Our thermodynamic model reveals that production of SO₃ (a potential precursor for near-source volcanic sulphate and hence ‘primary’ volcanic aerosol) is likely to be significantly lower from early Earth volcanism. Uncertainty in the pathway to near-source sulphate in modern volcanism (i.e., the reaction of SO₃ with water or direct emission) introduces a large uncertainty into the production rate of near-source volcanic sulphate on the early Earth.     

An automatic system for continuous monitoring of CO2, H2S, SO2 and meteorological parameters in the atmosphere of volcanic areas

An automatic system for the continuous monitoring of CO₂, H₂S, SO₂ and meteorological parameters in atmosphere has been developed. The system has been tested in the laboratory in order to verify the stability and reliability of each sensor and of the whole system. A field test for a period of one month, at the Solfatara of Pozzuoli has also been carried out. The acquired data during the field test reveal a correlation between the wind speed and the concentrations of CO₂, H₂S, and SO₂ in the atmosphere. With a wind speed of over 4 ms^-1 the concentration of the three gases reached constant background values of 600 ppm for CO₂ and about 2 ppm vol. for H₂S and SO₂. The different ratios of H₂S/SO₂ measured in the fumaroles (~100) and in the atmosphere (1–0.1) clearly indicate that H₂S is oxidized to SO₂ during the transport.     

Chemical monitoring of volcanic gas using remote FT-IR spectroscopy at several active volcanoes in Japan

Chemical compositions of volcanic gases of several Japanese active volcanoes have been monitored from distant safe places since the beginning of the 1990s using an FT-IR spectral radiometer. For absorption measurements, an infrared light source behind volcanic gas emissions is necessary in a volcanic environment. In the early observations, infrared radiation from hot lava domes (Unzen volcano) and hot ground heated by high-temperature fumaroles (Usu, Aso, and Satsuma-Iwojima volcanoes) were used as infrared light sources. However, these sources were not available in many cases. This remote FT-IR method became more commonly applied to chemical monitoring of volcanic gases emitted from the summit or slopes of active volcanoes using scattered solar infrared light as infrared light sources (Sakurajima, Miyakejima, and Asama volcanoes). To date, eight species have been measured using this method: SO₂, HCl, HF, CO, CO₂, COS, SiF₄, and H₂O. The observations indicate that volcanic gases for each volcano have different chemical composition on a SO₂–HCl–HF ternary diagram in spite of similar tectonic settings, suggesting that vapor/melt volume ratios during volcanic gas formation differ among volcanoes. During more than 15 years of monitoring, chemical changes in volcanic gases attributable to ascent of magma were observed only at Asama, where HCl/SO₂ and HF/HCl ratios in the eruptive period were higher than those in non-eruptive period because of scrubbing of more soluble components in surface hydrothermal systems in the non-eruptive stage or solubility-controlled fractionation processes. Results show that these parameters are the most prospective ones among the various parameters measured using the remote FT-IR method to monitor volcanic activities.     

Insights into the Hadean Earth from experimental studies of zircon

Geologists investigate the evolution of the atmosphere, crust, and mantle through time by direct study of the rock record. However, the Hadean eon (>3.85 Ga) has been traditionally viewed as inaccessible due to the absence of preserved rocks. The discovery of >4.0 Ga detrital zircons from Western Australia in the 1980s — coupled with the development of new micro-analytical capabilities — made possible new avenues of early Earth research. The prevailing view that emerged is that the early Earth may have contained a stable hydrosphere, water-saturated or (near watersaturated) granitic magmas, and volcanic emanations dominated by neutral gas species (e.g., CO₂, H₂O, and SO₂). The Hadean Earth may have been capable of supporting life ～200 Ma after accretion and perhaps earlier. Many of these models are formulated — or have been subsequently supported — by laboratory experiments of zircon. Important petrological variables such as temperature, pressure, oxygen fugacity, and component activities (e.g., SiO₂/TiO₂-activities) can be controlled. These experiments are fundamental for extrapolation to ‘deep time’ because they provide a means to understand primary chemistry preserved in ancient zircons. This review paper specifically focuses on zircon experimental studies (oxygen isotope fractionations, Ti-thermometry, and redox sensitive element incorporation into zircon), which have influenced our view of the very early Earth.     

Melt inclusion constraints on volatile systematics and degassing history of the 2014–2015 Holuhraun eruption,Iceland

The mass of volatiles emitted during volcanic eruptions is often estimated by comparing the volatile contents of undegassed melt inclusions, trapped in crystals at an early stage of magmatic evolution, with that of the degassed matrix glass. Here we present detailed characterisation of magmatic volatiles (H₂O, CO₂, S, Fl and Cl) of crystal-hosted melt and fluid inclusions from the 2014–2015 Holuhraun eruption of the Bárðarbunga volcanic system, Iceland. Based on the ratios of magmatic volatiles to similarly incompatible trace elements, the undegassed primary volatile contents of the Holuhraun parental melt are estimated at 1500–1700 ppm CO₂, 0.13–0.16 wt% H₂O, 60–80 ppm Cl, 130–240 ppm F and 500–800 ppm S. High-density fluid inclusions indicate onset of crystallisation at pressures?≥?0.4 GPa (~?12 km depth) promoting deep degassing of CO₂. Prior to the onset of degassing, the melt CO₂ content may have reached 3000–4000 ppm, with the total magmatic CO₂ budget estimated at  23–55 Mt. SO₂ release commenced at 0.12 GPa (~?3.6 km depth), eventually leading to entrapment of SO₂ vapour in low-density fluid inclusions. We calculate the syn-eruptive volatile release as 22.2 Mt of magmatic H₂O, 5.9–7.7 Mt CO₂, and 11.3 Mt of SO₂ over the course of the eruption; F and Cl release were insignificant. Melt inclusion constraints on syn-eruptive volatile release are similar to estimates made during in situ field monitoring, with the exception of H₂O, where field measurements may be heavily biased by the incorporation of meteoric water.     

The microdetermination of H2O,CO2, and SO2 in glass using a 1280°C microscope vacuum heating stage,cryopumping, and vapor pressure measurements from 77 to 273 K

A new microscope vacuum heating stage and gas analyzer has been developed for measurement of H₂O, CO₂, SO₂, and noncondensable gas (H₂, CO, N₂, Ar, CH₄, etc.) evolved from samples, particularly natural glass, at temperatures up to 1280°C. The gas evolved upon heating to 1280δC is collected in a liquid nitrogen cold trap. Gas components are identified by the characteristic vapor pressure and temperature ranges over which solid and vapor are in equilibrium during sublimation of individual components. The masses of CO₂, SO₂, and H₂O derived from samples and blanks are calculated using the ideal gas law, the molecular weights of the components, and the gauge constant (i.e. the ratio of the number of moles of a gas to its partial pressure in the constant volume). Results obtained by repeated determinations of H₂O, CO₂, and SO₂ evolved from a submarine basaltic glass from Kilauea volcano, Hawaii, (average sample mass = 3 × 10^?3 g) gave probable errors for the determinations of H₂O (0.23%), CO₂ (0.025%), and S (0.071%) equal to 4, 10, and 8% respectively, of the concentrations. Determinations of H₂O in smaller samples of H₂O-poor basaltic pumice show a linear proportionality (0.063%) between the measured H₂O and the sample mass over the range 0.1 × 10^?6 to 1.7 × 10^?6 g H₂O. Comparisons of H₂O determinations by this technique with those obtained by Penfield, gas chromatic, microcoulometric, and vacuum fusion techniques used elsewhere show reasonably good agreement. Determinations of SO₂ by this technique agree reasonably well X-ray fluorescence and electron microprobe determinations of sulfur. Determinations of CO₂ by the present technique are reproducible but cannot be compared directly to measurements made in other labs because of differences in samples analyzed. The principle advantages of this analytical technique are the very small sample required, the simultaneous determination of H₂O, CO₂, SO₂ and noncondensable gas, the avoidance of calibration procedures dependent on chemical standards, and the visual observations that can be made during sample outgassing.     

Activated release of alkalis during the vesiculation of molten basalts under high vacuum: implications for lunar volcanism

Knudsen cell-quadrupole mass spectrometry was used to study the high-temperature vaporization of Hawaiian basalts, plagioclase, tektites, and samples from the Allende meteorite. Procedures are described by which mass loss rates and vapor pressures of Na and K were measured quantitatively.Gas-rich glassy basalts were observed to vesiculate under vacuum over the 900–1000°C region and simultaneously evaporate alkalis in nonequilibrium fashion at rates (units of μg/g/hr) of approximately 200–300 Na and 75–250 K. Degassed residues of the same basalts demonstrated equilibrium evaporation rates (over the same temperature range) of 60–120 Na and 30–60 K. The gas-deficient plagioclase and tektite sample showed only equilibrium vaporization with rates of 60 Na, 10 K (plagioclase) and 10 Na, 5K (tektites) at 900–1000°C. The Allende meteorite vaporized at rates of 2400 Na and 200 K at 900–1000°C, possibly by the reaction of Na₂O and K₂O with C or S₂, or by the thermal decomposition of nepheline or sodalite.The nonequilibrium vaporization of alkalis from the gas-rich basalts is attributed to vigorous agitation of the melt during its vesiculation by a gas phase composed principally of SO₂, CO₂, H₂O, CO, and H₂S. The major gases released from the Allende meteorite at 900–1000°C are, in order of decreasing abundance, CO, S₂, CO₂, H₂O, SO₂, and H₂S.It is proposed that nonequilibrium vaporization of alkalis during the vesiculation of lunar lavas was responsible for the production of alkali-rich vapors which subsequently deposited plagioclase crystals in the vugs of lunar rocks. The vesiculative, nonequilibrium vaporization of Na and K during a lunar volcanic eruption should be expected to occur at a high rate upon initial extrusion of the lava into vacuum but then decrease by a factor of approximately three when degassing is nearing completion. Vaporization losses remain inadequate to explain the uniformly low alkali concentrations in lunar basalts.     

2002~2005年长白山火山气体的释放特征与地球化学异常研究——多源高光谱遥感证据

长白山火山区是我国具有潜在喷发危险的活火山,在2002~2005年火山活动性增强出现了岩浆房扰动。利用卫星遥感技术具有观测范围大、观测时间长且连续的优势。因此,本文利用对流层污染探测仪（MOPITT）和大气红外探测仪（AIRS）高光谱遥感数据提取了2002~2005年长白山天池火山区CO总量、O₃总量、水汽总量和地表温度异常信息,讨论了高光谱遥感气体地球化学异常信息与火山活动性之间的关系,并对2002~2005年长白山天池火山区火山活动性进行了研究。结果表明,高光谱遥感数据观测到的气体地球化学（CO、O₃、水汽）异常与地震、形变监测结果以及地面流体（CO₂、He、H₂）观测结果相一致,表明MOPITT和AIRS高光谱遥感卫星观测到的气体异常变化较好地反映了2002~2005年大规模的深部岩浆局部扰动。在2002~2005年火山活动期间,CO总量、O₃总量、水汽总量和地表温度均出现了显著异常且异常出现时段相应准偏差显著增大,反映了气体逸出量在时间上具有不均一性,可能与火山、地震活动过程中地应力的作用和变化有关。从气体异常持续的时间以及地面观测结果综合分析,2002~2005年岩浆房扰动并没有产生长时间的地幔物质流的上升和迁移。在火山活动性增强的时间段内,地表温度出现异常低值,这可能与太平洋板块俯冲过程中引起的断裂拉张增强有关。此外,火山活动过程中逸出的气体进入大气圈产生大气化学反应也会导致高光谱遥感所观测到的气体地球化学异常。研究结果为2002~2005年长白山火山活动性的研究提供了来自高光谱遥感数据的气体地球化学新证据,也对高光谱分辨率遥感数据在火山活动规律的研究以及火山监测中的应用具有一定意义。     

Volatiles in pillows of the Mid-Ocean-Ridge-Basalt (MORB) and vitreous basaltic rims

Temperature-resolved analyses of volatiles from Mid-Ocean-Ridge-Basalt (MORB) and vitreous basaltic rims were carried out to investigate the total volatile contents of basaltic melts and the influence of magma contamination on the degassing behaviour of volcanic rocks.With respect to the sources of methane evolution from the MORB the investigations are taken into consideration, the hydrocarbon (HC) release especially from the melt.The current paper presents data for H₂O, CO₂, SO₂, He, H₂, HF, HCl, CO, N₂, O₂, and HC degassing profiles of samples from the MORB sampling cruise 02.10.1983-11.11.1983 with FS Sonne 28 during the GEMINO-1 project near the Carlsberg Ridge (CR) and the Mid-Indian-Ocean-Ridge (MIOR).It aims to estimate the magnitude and nature of source magma volatiles and contamination (crustal material, seawater, atmospheric gases).The degassing of H₂O, CO₂, HCs as well as sulphur and chlorine species, or O₂ from vitreous specimens shows characteristic differences associated with sample position with respect to the lava surface.From the water release by bubbling and diffusion above 700 °C it must be concluded that any assimilation of sea water in vitreous rim is very low. The water content in the vitreous rim is about 0.1-0.2 wt%. The low interaction of melt with sea water is supported by the missing of a significant release of chlorine species during the heat treatment of the sample up to 1450 °C.Mixed H₂O/CO₂ bubbles escape between 700 and 800 °C from the vitreous rim. The CO₂ release in the temperature range of 1060-1170 °C from the basalt and the vitreous rim is interpreted as an indication for the primary carbon-dioxide content in the melt.Above 1100 °C CO₂ and SO₂ are evolved by both diffusion and small bubbles. The quantities of CO₂ in the vitreous rim and the basalt are similar (between 0.05 and 0.15 wt%), whereas the quantities of SO₂ escaping both from the vitreous rim and the crystalline basalt are between 0.013 and 0.024 wt%.Simultaneous with the CO₂ release by bubbling, HC species, especially CH fragments, were observed. The fact that the temperature of release maxima are above 1050 °C in both the vitreous rim and in the basalt is an indication for a geogenetic origin of HCs, e.g. methane.A low temperature of release for methane, which is consistent with biogenetic HC, was observed from the gas-release profiles of the basalts only. The maxima of the low-temperature gas releases are between 80 and 200 °C with a high correlation between the fragments m/z 13 and m/z 15. This correlation is a significant indication for a methane release.The oxygen release profiles of vitreous and crystalline basalts give significant indications for oxygen fugacity below the (QMF) of basaltic magma.Secondary minerals, generated by alteration of basaltic rocks, can be characterized by gas release profiles (GRPs) due to their decomposition in the temperature range below 800 °C. Only in the basalt were there observed indications of alteration processes. Small traces of carbonates (<0.0001 wt%) were detected by the gas release during the decomposition.Processes of degassing at temperatures higher than 800 °C are correlated to volatiles in the melt and to fluid inclusions of the minerals. There are no obvious correlations in the degassing characteristics between H₂O, CO₂ and SO₂. The different maxima of the degassing velocity, especially of CO₂, and SO₂, are indications of the different bonding forces of the site occupancy of the volatiles in the melt and in the glass. A micelle model for bonding sites in the basaltic glass for dissolved volatiles is discussed.     

Volatile constituents in magmatic inclusions

Laser Raman microprobe has been applied to the analysis of volatile components in shrinkage gas bubbles of individual magmatic inclusions in quartz crystal fragments and phenocrystals from the Mesozoic volcanic complexes of Tonglu and Shouchang, Zhejiang Province. Quantitative analyses are given for CO₂, CH₄, H₂O, CO, H₂, N₂, H₂S, and SO₂. In conjunction with the microthermometry and microbarometry data and the chemical composition of magmatic inclusions, the results permit one to calculate the physico-chemical parametersP _total,fO ₂ ,fCO ₂ ,fCH ₄ ,fH ₂O,fCO, andfH ₂ at the time individual magmatic inclusions were trapped. Based on the data obtained, some physico-chemical conditions for the Mesozoic volcanic magma evolution in the Tonglu and Shouchang areas are discussed. This work shows that this type of studies has become an indispensable new and rising domain in modern magmatic petrology, especially modern volcanic petrology. It can help us to reconstruct the physico-chemistry of the crystallization-evolution of a natural magma. The project was financially supported by the National Science Foundation of China.     

中国大陆新生代典型火山区温室气体释放的规模及其成因

火山活动能够将地球深部的碳输送到大气圈,是地质碳排放和深部碳循环的重要形式.火山作用不仅在喷发期能够释放大量温室气体,而且在休眠期也能释放巨量的温室气体.在全球变暖的背景下,定量化地研究火山活动对大气圈温室气体含量增加的贡献具有至关重要的意义.本文利用密闭气室法等该领域国际先进的测试技术,测量并计算了长白山、腾冲、五大连池及青藏高原南部的羊八井等典型火山区的温室气体释放规模.结果显示,我国大陆新生代典型火山区向大气圈输送的温室气体总通量约为8.13×10⁶t·a^-1,接近10⁷t·a^-1级别,相当于全球火山活动导致的温室气体(主要为CO₂)释放总量的6%左右.太平洋构造域火山区的温室气体在释放通量与总量方面均低于特提斯构造域,并且太平洋构造域火山气体的地壳混染程度较低,显示出大洋俯冲带与大陆俯冲带火山区温室气体释放的成因差异.     

High temperature mass spectrometric gas-release studies of Hawaiian volcanic glass: Pele's tears

The identification of gaseous molecular species and mechanisms of their release from glassy lava have been investigated with a high temperature mass spectrometer. Using Pele's tears as representative of quenched liquids of Hawaiian tholeiitic basalts, it was found that volatiles are released at low temperatures by a rate-limiting diffusion mechanism and, at temperatures in the softening range of the glass, by bursting of bubbles trapped near the vaporizing surface of the sphere-like particles.Gases released by bursting gave pressure surges and were found to be water vapor, CO₂ and CO. Those released principally by diffusion, and in some cases generated by thermal degradation and further reaction with the sample, include H₂, O₂, N₂, S₂, H₂S, SO₂, SO₃, COS, HCl, HF and NH₃. Average mole percent compositions of the volatiles H₂O, CO₂ and SO₂ relative to the total gas released were found to be 95 per cent, 3·5 per cent and 1 per cent, respectively. Minor concentrations of organic constituents, previously unobserved in volcanic gas analyses, were also found. Fragmentation patterns and gas release behavior suggest that these are derived from a mixture of low-molecular weight saturated and unsaturated acyclic hydrocarbons (C₁-C₄).     

Magmatic fluids of Tatun volcanic group,Taiwan

Two distinctive magmatic fluids were recognized in the Tatun volcanic group (TVG), Taiwan. One is a relatively reduced fluid represented by the fumarolic gases at Hsiao-you-ken (HYK) geothermal field. Another is an oxidized fluid containing high concentrations of HCl represented by the fumarolic gases at Da-you-ken (DYK). An intermediate gas was recognized at Gung-tze-ping (GTP) and She-hung-ping (SHP). The fumarolic gases at HYK and GTP possess the features of so-called primary steam generated on mixing of magmatic gas and meteoric groundwater. The fumarolic gases at DYK are a simple mixture between magmatic gas and water vapor of meteoric origin. The CO₂/H₂O molar ratio of the magmatic component in the fumarolic gases at DYK was estimated to be 0.018, meanwhile it was estimated to be 0.027 for the fumarolic gases at HYK and GTP, suggesting the magma beneath DYK is depleted in volatiles relative to the magma beneath HYK and GTP. The estimated CO₂/H₂O ratio for the magmatic component is comparable to that of some active volcanoes in Japan, suggesting the enrichment of volatiles in the magmas beneath TVG.     

Phase Chemistry Study of the Zabuye Salt Lake Brine: Isothermal Evaporation at 15°C and 25°C

Zabuye Salt Lake in Tibet, China is a carbonate-type salt lake, which has some unique characteristics that make it different from other types of salt lakes. The lake is at the latter period in its evolution and contains liquid and solid resources. Its brine is rich in Li, B, K and other useful minor elements that are of great economic value. We studied the concentration behavior of these elements and the crystallization paths of salts during isothermal evaporation of brine at 15°C and 25°C. The crystallization sequence of the primary salts from the brine at 25°C is halite (NaCl) → aphthitalite (3K2SO4·Na2SO4) → zabuyelite (Li2CO3)→ trona (Na2CO3·NaHCO3·2H2O) → thermonatrite (Na2CO3·H2O) → sylvite (KCl), while the sequence is halite (NaCl) → sylvite (KCl) → trona (Na2CO3·NaHCO3·2H2O) → zabuyelite (Li2CO3) → thermonatrite (Na2CO3·H2O) → aphthitalite (3K2SO4·Na2SO4) at 15°C. They are in accordance with the metastable phase diagram of the Na+, K+-Cl?, CO32?, SO42?-H2O quinary system at 25°C, except for Na2CO3·7H2O which is replaced by trona and thermonatrite. In the 25°C experiment, zabuyelite (Li2CO3) was precipitated in the early stage because Li2CO3 is supersaturated in the brine at 25°C, in contrast with that at 15°C, it precipitated in the later stage. Potash was precipitated in the middle and late stages in both experiments, while boron was concentrated in the early and middle stages and precipitated in the late stage.     

Ore Genesis of the Kalatongke Cu–Ni Sulfide Deposits, Western China: Constraints from Volatile Chemical and Carbon Isotopic Compositions

The Kalatongke Cu–Ni sulfide deposits located in the East Junggar terrane, northern Xinjiang, western China are the largest magmatic sulfide deposits in the Central Asian Orogenic Belt (CAOB). The chemical and carbon isotopic compositions of the volatiles trapped in olivine, pyroxene and sulfide mineral separates were analyzed by vacuum stepwise-heating mass spectrometry. The results show that the released volatiles are concentrated at three temperature intervals of 200–400°C, 400–900°C and 900–1200°C. The released volatiles from silicate mineral separates at 400–900°C and 900–1200°C have similar chemical and carbon isotopic compositions, which are mainly composed of H2O (av. ~92 mol%) with minor H2, CO2, H2S and SO2, and they are likely associated with the ore-forming magmatic volatiles. Light δ13CCO2 values (from ?20.86‰ to ?12.85‰) of pyroxene indicate crustal contamination occurred prior to or synchronous with pyroxene crystallization of mantle-derived ore-forming magma. The elevated contents of H2 and H2O in the olivine and pyroxene suggest a deep mantle-originated ore-forming volatile mixed with aqueous volatiles from recycled subducted slab. High contents of CO2 in the ore-forming magma volatiles led to an increase in oxygen fugacity, and thereby reduced the solubility of sulfur in the magma, then triggered sulfur saturation followed by sulfide melt segregation; CO2 contents correlated with Cu contents in the whole rocks suggest that a supercritical state of CO2 in the ore-forming magma system under high temperature and pressure conditions might play a key role in the assemblage of huge Cu and Ni elements. The volatiles released from constituent minerals of intrusion 1# have more CO2 and SO2 oxidized gases, higher CO2/CH4 and SO2/H2S ratios and lighter δ13CCO2 than those of intrusions 2# and 3#. This combination suggests that the higher oxidation state of the volatiles in intrusion 1# than intrusions 2# and 3#, which could be one of key ore-forming factors for large amounts of ores and high contents of Cu and Ni in intrusion 1#. The volatiles released at 200–400°C are dominated by H2O with minor CO2, N2+CO and SO2, with δ13CCO2 values (?25.66‰ to ?22.98‰) within the crustal ranges, and are considered to be related to secondary tectonic– hydrothermal activities.     

Melt and fluid inclusion evidence for a genetic relationship between magmatism in the Shuangliao volcanic field and inorganic CO2 gas reservoirs in the southern Songliao Basin,China

We have studied melt and fluid inclusions in minerals from alkali basalts, mantle xenoliths, and dawsonite-bearing sandstones from the Shuangliao volcanic field in southern Songliao Basin, Northeast China. The inclusions have been investigated using petrographic, geochemical, and laser Raman spectroscopic techniques. Volcanic rocks of the Shuangliao field are predominantly alkali olivine basalts that contain rare mantle xenoliths. Silicate melt and fluid inclusions are common in both olivine phenocrysts and the mantle xenoliths. The fluid inclusions are mainly composed of CO₂ with small amounts of CO, CH₄, N₂, and H₂O, which is consistent with an upper mantle origin. CO₂ gas reservoirs in the southern Songliao Basin are mostly derived from a mantle–magmatic source. Coeval fluid-inclusion homogenization temperatures, coupled with the thermal burial history, show that the CO₂ gas reservoirs in the southern Songliao Basin are Cenozoic (40–63 Ma) and coeval with the magmatism in the Shuangliao volcanic field. Despite the relatively small scale of this volcanic activity, it released large amounts of CO₂. Much of the magma was not erupted, and CO₂- and H₂O-rich magma was probably intruded into the basin along deep faults, acting as a major source of inorganic CO₂ gas in the southern Songliao Basin.     

Aquifer disposal of acid gases: modelling of water–rock reactions for trapping of acid wastes

The pore space of deep saline aquifers in the Alberta (sedimentary) Basin offers a significant volume for waste storage by “hydrodynamic trapping”. Furthermore, given the slow regional fluid flow in these deep saline aquifers, ample time exists for waste-water/rock chemical reactions to take place. A geochemical computer model (PATHARC) was used to compute the interaction of industrial waste streams comprising CO₂, H₂SO₄ and H₂S with the minerals in typical carbonate and sandstone aquifers from the Alberta Basin. The results support the idea that these acids can be neutralized by such reactions and that new mineral products are formed, such as calcite, siderite, anhydrite/gypsum and pyrrhotite, thereby trapping the CO₃, SO₄ and S ions that are formed when the acid gases dissolve in the formation water. Siliciclastic aquifers appear to be a better host for “mineral trapping” than carbonate aquifers, especially with regard to CO₂. Carbonate aquifers may be more prone to leakage due to high CO₂ pressures generated by reaction with H₂SO₄ and H₂S. Even though permeability decreases are expected due to this “mineral trapping”, they can be partially controlled so that plugging of the aquifer does not occur.     

Factors Controlling Precipitation of Barite and Witherite and Genesis of the Ankang–Xunyang Barium Deposits, Shaanxi, China

The barium deposits in Ankang and Xunyang counties,Shaanxi Province,China,occur in the northernmost part of the world-class barium metallogenic belt in south Qinling.The deposits are hosted by the Lower Silurian carbonaceous siliceous rocks,with a unique combination of barite and witherite.The homogenization temperatures of fluid inclusions in the barite are mainly concentrated between 135 and 155 ℃,whereas those from the witherite have two peaks of 165-175 ℃,and 215-225℃,respectively.Laser Raman analysis of fluid inclusions indicates that the vapor phase of fluid inclusions in barite is dominated by H_2O,although some contains N_2,H_2S,and CH_4.The compositions of the vapor and liquid phases of fluid inclusions in witherite can be divided into two end-members,one dominated by H_2O without other volatiles,and the other containing CH_4,C_2H_6,C_3H_8,C_2H_4,and C_6H_6 in addition to H_2O.CO_2,H_2S,and some CH_4 are interpreted as products of chemical reactions during mineralization.Organic gases(CH_4,C_2H_6,C_3H_8,C_2H_4,and C_6H_6) in the fluids were critical in the formation of barium sulfate versus carbonate.The δ~(34)S values of barite range from 38.26‰ to54.23‰(CDT),the δ~(34)S values of sulfides coexisting with barium minerals vary from 22.44‰ to25.11‰(CDT),and those in the wall rock from 11.60‰ to 19.06‰(CDT).We propose that the SO_4~(2-)generally experienced bacterial sulfate reduction in seawater before mineralization,and some SO_4~(2-)also experienced thermochemical sulfate reduction in hydrothermal system during mineralization.The δ~(13)C values of witherite range from-27.30‰ to-11.80‰(PDB),suggesting that carbon was sourced from organic substances(like CH_4,C_2H_4,and C_2H_6).The formation of witherite was possibly associated with thermochemical sulfate reduction,which caused the consumption of the organic gases and SO_4~(2-) in the hydrothermal solutions,consequently inhibiting barite formation.The important conditions for forming witherite include high fluid temperatures,high Ba~(2+) concentrations,CO_2 in the fluids,low HS~- concentrations,and the subsequent rapid diffusion of H_2S during thermochemical sulfate reduction of the fluids.     

Chemical composition of the primary aqueous phase of the earth and origin of life

Prokaryotes and cytoplasm of eukaryotes are dominated by K⁺, whereas the extracellular fluid of most species of multicellular organisms is dominated by Na⁺. It was substantiated that the K⁺/Na⁺ ratio in the salt constituent of the cells of modern organisms qualitatively reflects the proportions between these elements in the aqueous phase, in which the first forms of life and the protocell originated. The same conclusion is done by Armen Y. Mulkidjanian et al. (PNAS 13, 2012, E821-830). The chemical composition of primary aqueous phase of the Earth was reconstructed using thermodynamic numerical simulation of the equilibrium composition of the ??carbonaceous chondrite material-water??, ??primitive mantle material-water??, ??ultramafic rock-water??, ??mafic rocks-water?? systems that are open with respect to CO₂ and CH₄. It was shown that at 25°C, total pressure of 1 bar, and partial pressures of CO₂ and CH₄ 10^?5?C10^?8 and 10^?2?C10^?8 bar, respectively, the aqueous phase of the systems with carbonaceous chondrite and primitive mantle has K⁺/Na⁺ > 1, which corresponds to the proportions of these elements in the intracellular solution. The aqueous phase is characterized by pH = 8?C9, Eh = ?450 ± 50 mV, the presence of ammonium nitrogen, and concentrations of K, Na, and Mg close to those in the inferred intracellular fluid. The interaction of water with ultramafic and mafic rocks provides K⁺/Na⁺ < 1 in aqueous solution, which corresponds to the chemical composition of the modern natural waters of the Earth??s crust. Simulation results show that the protocell could arise in the primary aqueous phase of the Earth during differentiation of chondritic material into the Earth??s core and mantle, after the formation of the nitrogen atmosphere containing CH₄, CO₂, NH₃, H₂, H₂S, CO and other gases, but prior to the formation of the modern rocks of the Earth??s crust (first billion years of the planet??s lifetime).     

MIRIAM — a space-borne sun occultation experiment for atmospheric trace gas spectroscopy

The distribution of trace gases in earth's atmosphere will be analysed in a long term German-Russian space mission for more than three years, beginning in 1994. The FTIR-spectrometer, designed for this mission, has been tested with sun occultation measurements from the ground. The column contents of CH₄, CO₂, N₂O, CO, H₂, and O₃ could be retrieved. Spectral intervals for 25 different trace gases for the space mission have been identified and their retrieval accuracies were computed. The analysis shows, that with MIRIAM the lateral and vertical distribution of many trace gases can be analyzed as well as their long term variations.