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Kang, Zhiqin, Zhijing Wang, Yang Lu, Ran Cao, Dongwei Huang, and Qiaorong Meng. "Investigation on the Effect of Atmosphere on the Pyrolysis Behavior and Oil Quality of Jimusar Oil Shale." Geofluids 2022 (March 2, 2022): 1–9. http://dx.doi.org/10.1155/2022/1408690.
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High-temperature H2O and CO2 can improve the pyrolysis behavior of oil shale. Therefore, in this paper, Jimusar oil shale was selected as the research object and the effect of the reaction atmosphere (H2O, CO2, and N2) on its pyrolysis behavior, pyrolysate distribution, and pyrolysis oil quality was fully compared and studied. The results showed that compared with the N2 atmosphere, the presence of H2O and CO2 both increased the weight loss and weight loss rate during pyrolysis of oil shale and the existence of H2O advanced the initial precipitation temperature of volatiles by 17°C. The comprehensive release characteristic indices of volatiles during pyrolysis of oil shale in the CO2 and H2O atmospheres increased by 49.34% and 114.35%, respectively, which significantly improved its pyrolysis reactivity. Both H2O and CO2 atmospheres improved the pyrolysis oil yield of oil shale, and the pyrolysis oil yield in the H2O atmosphere performed better than that in the CO2 atmosphere. Especially, the H2O atmosphere could increase the pyrolysis oil yield by 41.42%. The existence of CO2 prevented methyl radicals from accepting hydrogen radicals during pyrolysis and reduced the alkane yield, while CO2 participated in the addition reaction of alkane, which increased the alkene yield. High-temperature H2O provided more hydrogen source, which increased the alkane yield and inhibited the alkene formation. Both H2O and CO2 atmospheres promoted the cracking of polycyclic aromatics and increased the yield of small-molecular aromatics in the pyrolysis oil. During the pyrolysis process of oil shale, CO2 and H2O underwent reforming reaction with the heavy oil, which increased the light component fraction, thereby increasing the H/C ratio of pyrolysis oil. Thus, the existence of H2O and CO2 atmospheres improved the quality of pyrolysis oil and the effect of H2O was better than CO2. The H2O and CO2 atmosphere promoted the formation of a well-developed pore structure, which was conducive to mass and heat transfer during pyrolysis of oil shale.
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Hoang, M., P. Garnier, H. Gourlaouen, J. Lasue, H. Rème, K. Altwegg, H. Balsiger, et al. "Two years with comet 67P/Churyumov-Gerasimenko: H2O, CO2, and CO as seen by the ROSINA/RTOF instrument of Rosetta." Astronomy & Astrophysics 630 (September 20, 2019): A33. http://dx.doi.org/10.1051/0004-6361/201834226.
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Context. The ESA Rosetta mission investigated the environment of comet 67P/Churyumov-Gerasimenko (hereafter 67P) from August 2014 to September 2016. One of the experiments on board the spacecraft, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) included a COmet Pressure Sensor (COPS) and two mass spectrometers to analyze the composition of neutrals and ions, the Reflectron-type Time-Of-Flight mass spectrometer (RTOF), and the Double Focusing Mass Spectrometer (DFMS). Aims. RTOF species detections cover the whole mission. This allows us to study the seasonal evolution of the main volatiles (H2O, CO2, and CO) and their spatial distributions. Methods. We studied the RTOF dataset during the two-year long comet escort phase focusing on the study of H2O, CO2, and CO. We also present the detection by RTOF of O2, the fourth main volatile recorded in the coma of 67P. This work includes the calibration of spectra and the analysis of the signature of the four volatiles. We present the analysis of the dynamics of the main volatiles and visualize the distribution by projecting our results onto the surface of the nucleus. The temporal and spatial heterogeneities of H2O, CO2, and CO are studied over the two years of mission, but the O2 is only studied over a two-month period. Results. The global outgassing evolution follows the expected asymmetry with respect to perihelion. The CO/CO2 ratio is not constant through the mission, even though both species appear to originate from the same regions of the nucleus. The outgassing of CO2 and CO was more pronounced in the southern than in the northern hemisphere, except for the time from August to October 2014. We provide a new and independent estimate of the relative abundance of O2. Conclusions. We show evidence of a change in molecular ratios throughout the mission. We observe a clear north-south dichotomy in the coma composition, suggesting a composition dichotomy between the outgassing layers of the two hemispheres. Our work indicates that CO2 and CO are located on the surface of the southern hemisphere as a result of the strong erosion during the previous perihelion. We also report a cyclic occurrence of CO and CO2 detections in the northern hemisphere. We discuss two scenarios: devolatilization of transported wet dust grains from south to north, and different stratigraphy for the upper layers of the cometary nucleus between the two hemispheres.
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FISCHER, TOBIAS P. "Fluxes of volatiles (H2O, CO2, N2, Cl, F) from arc volcanoes." GEOCHEMICAL JOURNAL 42, no. 1 (2008): 21–38. http://dx.doi.org/10.2343/geochemj.42.21.
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Peng, Jin Xing, Bei Bei Yan, Guan Yi Chen, Xin Li Zhu, and Chao Wang. "TG-FTIR Analysis of Wood Based Bio-Oil." Advanced Materials Research 347-353 (October 2011): 2661–65. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.2661.
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The combustion mechanism of bio-oil derived from wood fast pyrolysis was investigated by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG–FTIR) in flowing air. The results show that the combustion process of bio-oil consists of two main consecutive stages at a low heating rate. The combustion reaction becomes more and more intense from the first to the second stage. The release of volatiles occurs mainly at 80～200 °C and 350～500°C, and the gaseous products in each stage are different. The main products in the first stage are H2O with a few low molecule weight compounds, such as methanol, formic acid, etc. In the second stage, some new volatiles such as CO2, CO and CH4, etc. are present. Among the above volatiles, CO2 is the dominant gaseous product in the whole combustion process. The concentrations of CO2 and CO keep increasing, and reach the maximum at about 450 °C. Over 570°C, there are few products released at the end of the combustion process.
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Kruk, Aleksei, and Alexander Sokol. "Role of Volatiles in the Evolution of a Carbonatitic Melt in Peridotitic Mantle: Experimental Constraints at 6.3 GPa and 1200–1450 °C." Minerals 12, no. 4 (April 11, 2022): 466. http://dx.doi.org/10.3390/min12040466.
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Reconstruction of the mechanisms of carbonatitic melt evolution is extremely important for understanding metasomatic processes at the base of the continental lithospheric mantle (CLM). We have studied the interaction between garnet lherzolite and a carbonatitic melt rich in molecular CO2 and H2O in experiments at 6.3 GPa and 1200–1450 °C. The interaction with garnet lherzolite and H2O-bearing carbonatite melt leads to wehrlitization of lherzolite, without its carbonation. Introduction of molecular CO2 and H2O initiates carbonation of olivine and clinopyroxene with the formation of orthopyroxene and magnesite. Partial carbonation leads to the formation of carbonate–silicate melts that are multiphase saturated with garnet harzburgite. Upon complete carbonation of olivine already at 1200 °C, melts with 27–31 wt% SiO2 and MgO/CaO ≈ 1 are formed. At 1350–1450 °C, the interaction leads to an increase in the melt fraction and the MgO/CaO ratio to 2–4 and a decrease in the SiO2 concentration. Thus, at conditions of a thermally undisturbed CLM base, molecular CO2 and H2O dissolved in metasomatic agents, due to local carbonation of peridotite, can provide the evolution of agent composition from carbonatitic to hydrous silicic, i.e., similar to the trends reconstructed for diamond-forming high density fluids (HDFs) and genetically related proto-kimberlite melts.
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Morizet, Yann, Alexander R. L. Kohn Nichols, Richard A. Brooker, and Donald B. Dingwell. "The influence of H2O and CO2 on the glass transition temperature: insights into the effects of volatiles on magma viscosity." European Journal of Mineralogy 19, no. 5 (November 7, 2007): 657–69. http://dx.doi.org/10.1127/0935-1221/2007/0019-1751.
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Jerković, Igor, Marina Kranjac, Zvonimir Marijanović, Bojan Šarkanj, Ana-Marija Cikoš, Krunoslav Aladić, Sandra Pedisić, and Stela Jokić. "Chemical Diversity of Codium bursa (Olivi) C. Agardh Headspace Compounds, Volatiles, Fatty Acids and Insight into Its Antifungal Activity." Molecules 24, no. 5 (February 27, 2019): 842. http://dx.doi.org/10.3390/molecules24050842.
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The focus of present study is on Codium bursa collected from the Adriatic Sea. C. bursa volatiles were identified by gas chromatography and mass spectrometry (GC-FID; GC-MS) after headspace solid-phase microextraction (HS-SPME), hydrodistillation (HD), and supercritical CO2 extraction (SC-CO2). The headspace composition of dried (HS-D) and fresh (HS-F) C. bursa was remarkably different. Dimethyl sulfide, the major HS-F compound was present in HS-D only as a minor constituent and heptadecane percentage was raised in HS-D. The distillate of fresh C. bursa contained heptadecane and docosane among the major compounds. After air-drying, a significantly different composition of the volatile oil was obtained with (E)-phytol as the predominant compound. It was also found in SC-CO2 extract of freeze-dried C. bursa (FD-CB) as the major constituent. Loliolide (3.51%) was only identified in SC-CO2 extract. Fatty acids were determined from FD-CB after derivatisation as methyl esters by GC-FID. The most dominant acids were palmitic (25.4%), oleic (36.5%), linoleic (11.6%), and stearic (9.0%). FD-CB H2O extract exhibited better antifungal effects against Fusarium spp., while dimethyl sulfoxide (DMSO) extract was better for the inhibition of Penicillium expansum, Aspergillus flavus, and Rhizophus spp. The extracts showed relatively good antifungal activity, especially against P. expansum (for DMSO extract MIC50 was at 50 µg/mL).
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Hoang, M., P. Garnier, J. Lasue, H. Rème, M. T. Capria, K. Altwegg, M. Läuter, T. Kramer, and M. Rubin. "Investigating the Rosetta/RTOF observations of comet 67P/Churyumov-Gerasimenko using a comet nucleus model: influence of dust mantle and trapped CO." Astronomy & Astrophysics 638 (June 2020): A106. http://dx.doi.org/10.1051/0004-6361/201936655.
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Context. Cometary outgassing is induced by the sublimation of ices and the ejection of dust originating from the nucleus. Therefore measuring the composition and dynamics of the cometary gas provides information concerning the interior composition of the body. Nevertheless, the bulk composition differs from the coma composition, and numerical models are required to simulate the main physical processes induced by the illumination of the icy body. Aims. The objectives of this study are to bring new constraints on the interior composition of the nucleus of comet 67P/Churyumov-Gerasimenko (hereafter 67P) by comparing the results of a thermophysical model applied to the nucleus of 67P and the coma measurements made by the Reflectron-type Time-Of-Flight (RTOF) mass spectrometer. This last is one of the three instruments of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), used during the Rosetta mission. Methods. Using a thermophysical model of the comet nucleus, we studied the evolution of the stratigraphy (position of the sublimation and crystallisation fronts), the temperature of the surface and subsurface, and the dynamics and spatial distribution of the volatiles (H2O, CO2 and CO). We compared them with the in situ measurements from ROSINA/RTOF and an inverse coma model. Results. We observed the evolution of the surface and near surface temperature, and the deepening of sublimation fronts. The thickness of the dust layer covering the surface strongly influences the H2O outgassing but not the more volatiles species. The CO outgassing is highly sensitive to the initial CO/H2O ratio, as well as to the presence of trapped CO in the amorphous ice. Conclusions. The study of the influence of the initial parameters on the computed volatile fluxes and the comparison with ROSINA/RTOF measurements provide a range of values for an initial dust mantle thickness and a range of values for the volatile ratio. These imply the presence of trapped CO. Nevertheless, further studies are required to reproduce the strong change of behaviour observed in RTOF measurements between September 2014 and February 2015.
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Boulard, Eglantine, François Guyot, Nicolas Menguy, Alexandre Corgne, Anne-Line Auzende, Jean-Philippe Perrillat, and Guillaume Fiquet. "CO2-induced destabilization of pyrite-structured FeO2Hx in the lower mantle." National Science Review 5, no. 6 (March 15, 2018): 870–77. http://dx.doi.org/10.1093/nsr/nwy032.
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Abstract Volatiles, such as carbon and water, modulate the Earth's mantle rheology, partial melting and redox state, thereby playing a crucial role in the Earth's internal dynamics. We experimentally show the transformation of goethite FeOOH in the presence of CO2 into a tetrahedral carbonate phase, Fe4C3O12, at conditions above 107 GPa—2300 K. At temperatures below 2300 K, no interactions are evidenced between goethite and CO2, and instead a pyrite-structured FeO2Hx is formed as recently reported by Hu et al. (2016; 2017) and Nishi et al. (2017). The interpretation is that, above a critical temperature, FeO2Hx reacts with CO2 and H2, yielding Fe4C3O12 and H2O. Our findings provide strong support for the stability of carbon-oxygen-bearing phases at lower-mantle conditions. In both subducting slabs and lower-mantle lithologies, the tetrahedral carbonate Fe4C3O12 would replace the pyrite-structured FeO2Hx through carbonation of these phases. This reaction provides a new mechanism for hydrogen release as H2O within the deep lower mantle. Our study shows that the deep carbon and hydrogen cycles may be more complex than previously thought, as they strongly depend on the control exerted by local mineralogical and chemical environments on the CO2 and H2 thermodynamic activities.
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Callegaro, Sara, Kalotina Geraki, Andrea Marzoli, Angelo De Min, Victoria Maneta, and Don R. Baker. "The quintet completed: The partitioning of sulfur between nominally volatile-free minerals and silicate melts." American Mineralogist 105, no. 5 (May 1, 2020): 697–707. http://dx.doi.org/10.2138/am-2020-7188.
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Abstract Magmatic systems are dominated by five volatiles, namely H2O, CO2, F, Cl, and S (the igneous quintet). Multiple studies have measured partitioning of four out of these five volatiles (H2O, CO2, F, and Cl) between nominally volatile-free minerals and melts, whereas the partitioning of sulfur is poorly known. To better constrain the behavior of sulfur in igneous systems we measured the partitioning of sulfur between clinopyroxene and silicate melts over a range of pressure, temperature, and melt composition from 0.8 to 1.2 GPa, 1000 to 1240 °C, and 49 to 66 wt% SiO2 (13 measurements). Additionally, we determined the crystal-melt partitioning of sulfur for plagioclase (6 measurements), orthopyroxene (2 measurements), amphibole (2 measurements), and olivine (1 measurement) in some of these same run products. Experiments were performed at high and low oxygen fugacities, where sulfur in the melt is expected to be dominantly present as an S6+ or an S2– species, respectively. When the partition coefficient is calculated as the total sulfur in the crystal divided by the total sulfur in the melt, the partition coefficient varies from 0.017 to 0.075 for clinopyroxene, from 0.036 to 0.229 for plagioclase, and is a maximum of 0.001 for olivine and of 0.003 for orthopyroxene. The variation in the total sulfur partition coefficient positively correlates with cation-oxygen bond lengths in the crystals; the measured partition coefficients increase in the order: olivine < orthopyroxene < clinopyroxene ≤ amphibole and plagioclase. At high oxygen fugacities in hydrous experiments, the clinopyroxene/melt partition coefficients for total sulfur are only approximately one-third of those measured in low oxygen fugacity, anhydrous experiments. However when the partition coefficient is calculated as total sulfur in the crystal divided by S2– in the melt, the clinopyroxene/melt partition coefficients for experiments with melts between ~51 and 66 wt% SiO2 can be described by a single mean value of 0.063 ± 0.010 (1σ standard deviation about the mean). These two observations support the hypothesis that sulfur, as S2–, replaces oxygen in the crystal structure. The results of hydrous experiments at low oxygen fugacity and anhydrous experiments at high oxygen fugacity suggest that oxygen fugacity has a greater effect on sulfur partitioning than water. Although the total sulfur clinopyroxene-melt partition coefficients are affected by the Mg/(Mg+Fe) ratio of the crystal, partition coefficients calculated using S2– in the melt display no clear dependence upon the Mg# of the clinopyroxene. Both the bulk and the S 2– partition coefficients appear unaffected by IVAl in the clinopyroxene structure. No effect of anorthite content nor of iron concentration in the crystal was seen in the data for plagioclase-melt partitioning. The data obtained for orthopyroxene and olivine were too few to establish any trends. The partition coefficients of total sulfur and S 2– between the crystals studied and silicate melts are typically lower than those of fluorine, higher than those of carbon, and similar to those of chlorine and hydrogen. These sulfur partition coefficients can be combined with analyses of volatiles in nominally volatile-free minerals and previously published partition coefficients of H2O, C, F, and Cl to constrain the concentration of the igneous quintet, the five major volatiles in magmatic systems.
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Hirschmann, Marc M. "Comparative deep Earth volatile cycles: The case for C recycling from exosphere/mantle fractionation of major (H2O, C, N) volatiles and from H2O/Ce, CO2/Ba, and CO2/Nb exosphere ratios." Earth and Planetary Science Letters 502 (November 2018): 262–73. http://dx.doi.org/10.1016/j.epsl.2018.08.023.
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JESUS, J. V. M., A. C. SANTOS, J. C. MENDES, W. H. SANTOS, C. A. Q. REGO, and M. C. GERALDES. "Davis Bank Petrogenesis, Vitória-Trindade Chain, South Atlantic: Volatiles Role (H2O and CO2) in the Davis Bank Magmatic Evolution." Anuário do Instituto de Geociências - UFRJ 42, no. 3 (September 30, 2019): 237–53. http://dx.doi.org/10.11137/2019_3_237_253.
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Worzakowska, Marta. "The preparation, physicochemical and thermal properties of the high moisture, solvent and chemical resistant starch-g-poly(geranyl methacrylate) copolymers." Journal of Thermal Analysis and Calorimetry 140, no. 1 (September 19, 2019): 189–98. http://dx.doi.org/10.1007/s10973-019-08801-9.
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Abstract The thermal properties together with the identification of the emitted volatiles during heating of the starch-graft-poly(geranyl methacrylate) copolymers with the use of a TG/FTIR-coupled method and some of the physicochemical properties of the copolymers were determined. It was found that the use of the geranyl methacrylate monomer to the graft copolymerization with potato starch allowed to replace ca. 1.46 hydroxyl groups per glycosidic units of starch macromolecule by the poly(geranyl methacrylate) chains under the optimal reaction conditions. Generally, all tested starch graft copolymers exhibited a significant increase in polar solvent resistance, moisture resistance and chemical stability as compared to potato starch. However, the thermal stability of the obtained materials was substantially lower as compared to the thermal stability of potato starch. The beginning of the decomposition of the copolymers was observed below 150 °C. It was due to low thermal stability of the poly(geranyl methacrylate) chains. The decomposition of the prepared materials runs at least four, unseparated stages. The first stage was visible up to 220–240 °C. It was connected with the emission of some aldehyde, acid, alcohol, alkene, ester fragments, H2O and CO2 as a result of the depolymerization, destruction and partial decarboxylation of the poly(geranyl methacrylate) chains. The second stage was spread between ca. 220–240 and 358–375 °C. The emission of organic, saturated, unsaturated, aromatic, oxygen-rich fragments, CO, CO2 and H2O as a result of the decomposition and dehydration of starch was confirmed. Heating of the studied materials between 358–375 and 455–477 °C resulted in subsequent decomposition processes of the residues and the creation of some oxygen-rich saturated and unsaturated fragments, CO, CO2, H2O and CH4. Finally, above 455–477 °C, a minor mass loss as a result of the decomposition processes of the residues formed before was observed. The emission of CO, CO2, H2O, CH4 and some oxygen-rich saturated and unsaturated fragments was confirmed.
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Giuliani, Andrea, and D. Graham Pearson. "Kimberlites: From Deep Earth to Diamond Mines." Elements 15, no. 6 (December 1, 2019): 377–80. http://dx.doi.org/10.2138/gselements.15.6.377.
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Kimberlites are rare, enigmatic, low-volume igneous rocks. They are highly enriched in magnesium, volatiles (CO2 and H2O) and incompatible trace elements and are thought to be the most deeply derived (>150 km) magmatic rocks on Earth. Kimberlites occur in ancient and thick continental lithosphere, forming intrusive sheets and composite pipes, commonly in clusters. Despite their rarity, kimberlites have attracted considerable attention because they entrain not only abundant mantle fragments but also diamonds, which can provide a uniquely rich picture of the deep Earth. This issue summarises current thinking on kimberlite petrology, geochemistry, and volcanology and outlines the outstanding questions on the genesis of kimberlites and associated diamond mines.
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Setina, Janina. "Preparation of Synthetic Cordierite by Solide-State-Reaction with Addition of Dolomite." Advances in Science and Technology 45 (October 2006): 77–82. http://dx.doi.org/10.4028/www.scientific.net/ast.45.77.
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Cordierite was obtained from the mixture of aluminum hydroxide, sand, different magnesium compounds by a solid-state reaction method. The effect of dolomite doping on phase-transformation kinetics and microstructure has been investigated during thermal treatment by keeping a stoichiometric cordierite compound. Adding of dolomite has been used as a flux for preparation of a cordierite precursor by a coprecipitation process. Subsequently, DTA and XRD analyses were conducted to identify the phases formed in the sintered products. Morphological changes of the ground mixtures and sintered product were observed using SEM. The crystallization process of metastable quartz like μ-cordierite can be obtained at 1250…13000C. In this range of temperature form other compounds, such as spinel, quartz. Increase of sintering temperature and prolonged holding times promote the formation of only one phase – indialite or α-cordierite, the hexagonal form of cordierite. Experimental observation shows two steps in the solid-state reaction. First step – formation of volatiles compounds and pores, second – formation and growing of crystalline phases. Evolution of CO, CO2 and H2O that occurred during the thermal treatment of compositions is very important fact in the nucleation process. The intensity of crystallization depends on the gas volume and amount of pore in the sample. The experiments indicated that the intrinsic concentration of volatiles like CO, CO2, H2O influence the appearance of the cordierite phase. SEM photographs sowed that crystallization of cordierite start on the surface of pore. Growth of α-cordierite inside of pores is considerably affected by the time of thermal treatment and amount of adding of dolomite. A remarkable change in peak intensity of XRD patterns of the compositions was observed. Up to 20 wt. % addition of dolomite to the precursor allowed the fabrication of synthetic cordierite at lower temperature.
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Fiege, Adrian, Francesco Vetere, Gianluca Iezzi, Adam Simon, and François Holtz. "The roles of decompression rate and volatiles (H2O + Cl ± CO2± S) on crystallization in (trachy-) basaltic magma." Chemical Geology 411 (September 2015): 310–22. http://dx.doi.org/10.1016/j.chemgeo.2015.07.016.
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Guilhaumou, N., P. Dumas, G. L. Carr, and G. P. Williams. "Synchrotron Infrared Microspectrometry Applied to Petrography in Micrometer-Scale Range: Fluid Chemical Analysis and Mapping." Applied Spectroscopy 52, no. 8 (August 1998): 1029–34. http://dx.doi.org/10.1366/0003702981944797.
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The potentiality of synchrotron infrared microspectrometry was investigated for in situ analysis of fluid inclusions and volatiles of particular geological interest. Thanks to the intrinsic high brightness of the synchrotron infrared source, areas as small as a few μm2 can be probed, providing a high-contrast analysis of small inclusions in geological materials. We have identified organic components in such small volumes in their liquid and gaseous phase, thus allowing a deeper analysis of oil-water inclusions entrapped in diagenetic cements. Such detailed analysis opens up new perspectives in petroleum reservoir evolution studies. The high signal-to-noise ratio of spectra obtained in small volume allows a fast and accurate chemical mapping of the inclusion components. Drastic refraction effects preclude, at the present state, a quantitative analysis of either the volume or the thickness of the individual inclusions. Traces of volatiles such as CO2 and H2O are easily detected in the vitreous and gaseous part of the glass melt fluid inclusions. We have also profiled the hydroxyl concentration near a wall, and calculated the hydrogen diffusion coefficient in anhydrous minerals such as diopside.
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Barkov, Andrei Y., Andrey A. Nikiforov, Robert F. Martin, and Vladimir N. Korolyuk. "Corona-Type Textures in Ultrabasic Complexes of the Serpentinite Belt, Kola Peninsula, Russia." Minerals 13, no. 1 (January 11, 2023): 115. http://dx.doi.org/10.3390/min13010115.
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For the first time, corona-type textures are described in ultrabasic rocks in three complexes of the Serpentinite Belt on the Kola Peninsula in the northeastern Fennoscandian Shield. Three variants of the corona texture formed at different stages during the crystallization of a komatiitic, Al-undepleted melt emplaced in a subvolcanic setting. The first type crystallized at an early stage (Mg# Ol = 87) in a fine-grained harzburgite of the Chapesvara-I sill, with the following order in the corona: Ol → Opx → Cpx → Pl → Amp (aluminous sodic-calcic). The second type displays the sequence Opx → Cpx → Amp → Pl → Qz, which is observed in the orthopyroxenite zone in the Lotmvara-I sill. The third type involves a symplectitic corona in a plagioclase-bearing orthopyroxenite in the Lyavaraka complex, in which the inferred order is: Cpx → Amp (aluminous hornblende) + symplectitic Qz, formed in direct contact with grains of Pl. The corona-type textures occur in fresh rocks and are not related to regional metamorphism. They likely formed as consequences of two important factors: (1) rapid cooling, leading to unsteady conditions of crystallization in a shallow setting; and (2) an intrinsic enrichment in H2O and other volatiles in the parental magma, giving rise to fluid-saturated environments at advanced stages of crystallization. This was followed by a deuteric deposition of Amp rims as a result of the accumulation of H2O and reaction of H2O-bearing fluid with early grains of pyroxene and late plagioclase. The likely existence of a close relationship is suggested by the drusites of the Belomorian complex, which are coeval. In addition, unusual occurrences of lamellar inclusions of phlogopite and Al2SiO5 are documented, hosted by interstitial grains of plagioclase in the orthopyroxenite zone of the Lotmvara-I sill. These are attributed to crystallization from late portions of remaining melt enriched in Al, K, Na, H2O, and Cl, which is indicated by the recorded occurrence of chlorapatite in this association. Thus, our findings indicate the presence and abundance of intrinsic volatiles, Cl, F, CO2, and especially magmatic H2O, which were important to lower the liquidus, decrease the density and viscosity of the highly magnesian melt of Al-undepleted komatiite, thus enabling its transport from the mantle to a shallow level in the crust.
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Krissansen-Totton, J., and J. J. Fortney. "Predictions for Observable Atmospheres of Trappist-1 Planets from a Fully Coupled Atmosphere–Interior Evolution Model." Astrophysical Journal 933, no. 1 (July 1, 2022): 115. http://dx.doi.org/10.3847/1538-4357/ac69cb.
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Abstract The Trappist-1 planets provide a unique opportunity to test the current understanding of rocky planet evolution. The James Webb Space Telescope is expected to characterize the atmospheres of these planets, potentially detecting CO2, CO, H2O, CH4, or abiotic O2 from water photodissociation and subsequent hydrogen escape. Here, we apply a coupled atmosphere–interior evolution model to the Trappist-1 planets to anticipate their modern atmospheres. This model, which has previously been validated for Earth and Venus, connects magma ocean crystallization to temperate geochemical cycling. Mantle convection, magmatic outgassing, atmospheric escape, crustal oxidation, a radiative-convective climate model, and deep volatile cycling are explicitly coupled to anticipate bulk atmospheres and planetary redox evolution over 8 Gyr. By adopting a Monte Carlo approach that samples a broad range of initial conditions and unknown parameters, we make some tentative predictions about current Trappist-1 atmospheres. We find that anoxic atmospheres are probable, but not guaranteed, for the outer planets; oxygen produced via hydrogen loss during the pre-main sequence is typically consumed by crustal sinks. In contrast, oxygen accumulation on the inner planets occurs in around half of all models runs. Complete atmospheric erosion is possible but not assured for the inner planets (occurs in 20%–50% of model runs), whereas the outer planets retain significant surface volatiles in virtually all model simulations. For all planets that retain substantial atmospheres, CO2-dominated or CO2–O2 atmospheres are expected; water vapor is unlikely to be a detectable atmospheric constituent in most cases. There are necessarily many caveats to these predictions, but the ways in which they misalign with upcoming observations will highlight gaps in terrestrial planet knowledge.
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Johnson, Emily R., Paul J. Wallace, Katharine V. Cashman, and Hugo Delgado Granados. "Degassing of volatiles (H2O, CO2, S, Cl) during ascent, crystallization, and eruption at mafic monogenetic volcanoes in central Mexico." Journal of Volcanology and Geothermal Research 197, no. 1-4 (November 2010): 225–38. http://dx.doi.org/10.1016/j.jvolgeores.2010.02.017.
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Barmina, Inesa, Harijs Kalis, Antons Kolmickovs, Maksims Marinaki, Liiva Ozola, Uldis Strautins, Raimonds Valdmanis, and Maija Zake. "MATHEMATICAL MODELLING AND EXPERIMENTAL STUDY OF STRAW CO-FIRING WITH GAS." Mathematical Modelling and Analysis 24, no. 4 (October 25, 2019): 507–29. http://dx.doi.org/10.3846/mma.2019.031.
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The main goal of the present study is to promote a more effective use of agriculture residues (straw) as an alternative renewable fuel for cleaner energy production with reduced greenhouse gas emissions. With the aim to improve the main combustion characteristics at thermo-chemical conversion of wheat straw, complex experimental study and mathematical modelling of the processes developing when co-firing wheat straw pellets with a gaseous fuel were carried out. The effect of co-firing on the main gasification and combustion characteristics was studied experimentally by varying the propane supply and additional heat input into the pilot device, along with the estimation of the effect of co-firing on the thermal decomposition of wheat straw pellets, on the formation, ignition and combustion of volatiles (CO, H2). A mathematical model has been developed using the environment of the Matlab (2D modelling) and MATLAB package ”pdepe”(1D modelling) considering the variations in supplying heat energy and combustible volatiles (CO, H2) into the bottom of the combustor. Dominant exothermal chemical reactions were used to evaluate the effect of co-firing on the main combustion characteristics and composition of the products CO2 and H2O. The results prove that the additional heat from the propane flame makes it possible to control the thermal decomposition of straw pellets, the formation, ignition and combustion of volatiles and the development of combustion dynamics, thus completing the combustion of biomass and leading to cleaner heat energy production.
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Iacovino, Kayla, Kim Ju-Song, Thomas Sisson, Jacob Lowenstern, Ri Kuk-Hun, Jang Jong-Nam, Song Kun-Ho, et al. "Quantifying gas emissions from the “Millennium Eruption” of Paektu volcano, Democratic People’s Republic of Korea/China." Science Advances 2, no. 11 (November 2016): e1600913. http://dx.doi.org/10.1126/sciadv.1600913.
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Paektu volcano (Changbaishan) is a rhyolitic caldera that straddles the border between the Democratic People’s Republic of Korea and China. Its most recent large eruption was the Millennium Eruption (ME; 23 km3dense rock equivalent) circa 946 CE, which resulted in the release of copious magmatic volatiles (H2O, CO2, sulfur, and halogens). Accurate quantification of volatile yield and composition is critical in assessing volcanogenic climate impacts but is challenging, particularly for events before the satellite era. We use a geochemical technique to quantify volatile composition and upper bounds to yields for the ME by examining trends in incompatible trace and volatile element concentrations in crystal-hosted melt inclusions. We estimate that the ME could have emitted as much as 45 Tg of S to the atmosphere. This is greater than the quantity of S released by the 1815 eruption of Tambora, which contributed to the “year without a summer.” Our maximum gas yield estimates place the ME among the strongest emitters of climate-forcing gases in the Common Era. However, ice cores from Greenland record only a relatively weak sulfate signal attributed to the ME. We suggest that other factors came into play in minimizing the glaciochemical signature. This paradoxical case in which high S emissions do not result in a strong glacial sulfate signal may present a way forward in building more generalized models for interpreting which volcanic eruptions have produced large climate impacts.
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Rasmussen, Daniel J., Terry A. Plank, Paul J. Wallace, Megan E. Newcombe, and Jacob B. Lowenstern. "Vapor-bubble growth in olivine-hosted melt inclusions." American Mineralogist 105, no. 12 (December 1, 2020): 1898–919. http://dx.doi.org/10.2138/am-2020-7377.
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Abstract Melt inclusions record the depth of magmatic processes, magma degassing paths, and volatile budgets of magmas. Extracting this information is a major challenge. It requires determining melt volatile contents at the time of entrapment when working with melt inclusions that have suffered post-entrapment modifications. Several processes decrease internal melt inclusion pressure, resulting in nucleation and growth of a vapor bubble and, time permitting, diffusion of volatiles (especially CO2) into the vapor bubble. Previous studies have shown how this process may lead to most of the CO2 in the bulk melt inclusion being lost to the bubble. Without reconstruction, most of the melt inclusion data in the literature vastly underestimate the CO2 concentrations of magmas by measuring the glass phase only. Methods exist that attempt to reconstruct the entrapped CO2 contents, but they can be difficult to apply and do not always yield consistent results. Here, we explore bubble growth, evaluate CO2 reconstruction approaches, and develop improved experimental and computational approaches. Piston-cylinder experiments were conducted on olivine-hosted melt inclusions from Seguam (Alaska, U.S.A.) and Fuego (Guatemala) volcanoes at the following conditions: 500–800 MPa, 1140–1200 °C for Seguam and 1110–1140 °C for Fuego, 4–8 wt% H2O in the KBr brine filling the experimental capsules, and run durations of 10–120 min. Heated melt inclusions form well-defined S-CO2 trends consistent with degassing models. CO2 contents are enriched by a factor of ~2.5, on average, relative to those of the glasses in unheated melt inclusions, whereas S contents of heated and unheated melt inclusion glasses overlap, indicating that insignificant amounts of S partition into the vapor bubble. For naturally quenched melt inclusions, relatively low closure temperatures for CO2 diffusion enables some CO2 to enter vapor bubbles during quench, whereas higher closure temperatures for S diffusion limits its loss to vapor bubbles. We evaluate the timescales of post-entrapment processes and use the results to develop a new computational model to restore entrapped CO2 contents: melt inclusion modification corrections (MIMiC). Heated melt inclusion data are used as a benchmark to evaluate the results from MIMiC and other published methods of CO2 reconstruction. The methods perform variably well. Key advantages to our experimental technique are accurate measurements of CO2 contents and efficient rehomogenization of large quantities of melt inclusions. Our new computational model produces more accurate results than other computational methods, has similar accuracy to the Raman method of CO2 reconstruction in cases where Raman can be applied (i.e., no C-bearing phases in the bubble), and can be applied to the vast body of published melt inclusion data. To obtain the most robust data on bubble-bearing melt inclusions, we recommend taking both experimental- and MIMiC-based approaches.
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Kalvāns, Juris, and Juris Roberts Kalnin. "Evaporative cooling of icy interstellar grains." Astronomy & Astrophysics 633 (January 2020): A97. http://dx.doi.org/10.1051/0004-6361/201936471.
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Context. While radiative cooling of interstellar grains is a well-known process, little detail is known about the cooling of grains with an icy mantle that contains volatile adsorbed molecules. Aims. We explore basic details for the cooling process of an icy grain with properties relevant to dark interstellar clouds. Methods. Grain cooling was described with the help of a numerical code considering a grain with an icy mantle that is structured in monolayers and containing several volatile species in proportions consistent with interstellar ice. Evaporation was treated as first-order decay. Diffusion and subsequent thermal desorption of bulk-ice species was included. Temperature decrease from initial temperatures of 100, 90, 80, 70, 60, 50, 40, 30, and 20 K was studied, and we also followed the composition of ice and evaporated matter. Results. We find that grain cooling occurs by partially successive and partially overlapping evaporation of different species. The most volatile molecules (such as N2) first evaporate at the greatest rate and are most rapidly depleted from the outer ice monolayers. The most important coolant is CO, but evaporation of more refractory species, such as CH4 and even CO2, is possible when the former volatiles are not available. Cooling of high-temperature grains takes longer because volatile molecules are depleted faster and the grain has to switch to slow radiative cooling at a higher temperature. For grain temperatures above 40 K, most of the thermal energy is carried away by evaporation. Evaporation of the nonpolar volatile species induces a complete change of the ice surface, as the refractory polar molecules (H2O) are left behind. Conclusions. The effectiveness of thermal desorption from heated icy grains (e.g., the yield of cosmic-ray-induced desorption) is primarily controlled by the thermal energy content of the grain and the number and availability of volatile molecules.
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Gundlach, B., M. Fulle, and J. Blum. "On the activity of comets: understanding the gas and dust emission from comet 67/Churyumov–Gerasimenko’s south-pole region during perihelion." Monthly Notices of the Royal Astronomical Society 493, no. 3 (February 14, 2020): 3690–715. http://dx.doi.org/10.1093/mnras/staa449.
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ABSTRACT When comets approach the Sun, their surface is heated and the volatile species start to sublimate. Due to the increasing gas pressure, dust is ejected off the surface, which can be observed as cometary coma, dust tail, and trail. However, the underlying physical processes are not fully understood. Using state-of-the-art results for the transport of heat and gas as well as of the mechanical properties of cometary matter, we intend to describe the activity pattern of comets when they approach the Sun. We developed a novel thermophysical model to simulate the dust ejection from comet 67/Churyumov–Gerasimenko’s south-pole region at perihelion. Based on the input parameters, this model computes the sub-surface temperature profile, the pressure build-up, and the redistribution of volatiles inside the cometary sub-surface region and provides mass-loss rates of dust and gas as well as typical sizes and ice content of the ejected dust chunks. Our thermophysical model allows for continuous gas and dust ejection from the Southern hemisphere of comet 67/Churyumov–Gerasimenko at perihelion. We find that the model output is in general agreement with the observed Rosetta data. The sublimation of CO2 ice drives the ejection of very large ($\gtrsim 10\, \mathrm{cm}$) chunks, which contain $10\, {{\ \rm per\ cent}}$ to $90 \, {{\ \rm per\ cent}}$ of the initial water–ice content. In contrast, the outgassing of H2O ice causes the lift-off of small clusters of dust aggregates, which contain no ice.
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Ehrenfreund, P., and W. A. Schutte. "Infrared Observations of Interstellar Ices." Symposium - International Astronomical Union 197 (2000): 135–46. http://dx.doi.org/10.1017/s0074180900164745.
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In the recent years revolutionary results concerning the nature of icy dust particles have been obtained with the help of the Infrared Space Observatory (ISO) and ground based observations. To date interstellar ice features of H2O, CO, CO2, CH3OH, CH4, H2CO, OCS and HCOOH as well as other minor species are observed. Interstellar grains act as important catalysts in the interstellar medium. Processes such as UV irradiation, cosmic ray processing and temperature variations determine the grain mantle growth and chemical evolution. ISO has revealed that ice segregation is an important and ubiquitous process in the vicinity of massive protostars and reflects the extensive thermal processing of grains in such environments.In this paper a recent view on the inventory of interstellar ices is presented. Constraints on the reservoirs of oxygen in dense clouds are discussed, taking into account recent measurements of oxygen-bearing species. Large abundances of CO2 and CH3OH in dense molecular clouds provide challenging perspectives to investigate the differences of ice chemistry in the vicinity of high and low-mass protostars. Accurate abundances of ice species and knowledge on the ice distribution in the protostellar regions are an important tool to define the environmental conditions in molecular clouds. A global understanding of interstellar ice chemistry also allows monitoring the incorporation and evolution of volatiles in planetesimals and comets and to reveal processes predominant in the early Solar System.
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Khattak, Zafar A. K., Nazir Ahmad, Hussein A. Younus, Habib Ullah, Baoyi Yu, Khurram S. Munawar, Muhammad Ashfaq, Sher Ali, Hossain M. Shahadat, and Francis Verpoort. "Synthesis of 3D Cadmium(II)-Carboxylate Framework Having Potential for Co-Catalyst Free CO2 Fixation to Cyclic Carbonates." Inorganics 10, no. 10 (October 1, 2022): 162. http://dx.doi.org/10.3390/inorganics10100162.
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Metal-organic frameworks (MOFs) are porous coordination polymers with interesting structural frameworks, properties, and a wide range of applications. A novel 3D cadmium(II)-carboxylate framework, CdMOF ([Cd2(L)(DMF)(H2O)2]n), was synthesized by the solvothermal method using a tetracarboxylic bridging linker having amide functional moieties. The CdMOF crystal structure exists in the form of a 3D layer structure. Based on the single-crystal X-ray diffraction studies, the supramolecular assembly of CdMOF is explored by Hirshfeld surface analysis. The voids and cavities analysis is performed to check the strength of the crystal packing in CdMOF. The CdMOF followed a multistage thermal degradation pattern in which the solvent molecules escaped around 200 °C and the structural framework remained stable till 230 °C. The main structural framework collapsed (>60 wt.%) into organic volatiles between 400–550 °C. The SEM morphology analyses revealed uniform wedge-shaped rectangular blocks with dimensions of 25–100 μm. The catalytic activity of CdMOF for the solvent and cocatalyst-free cycloaddition of CO2 into epichlorohydrin was successful with 100% selectivity. The current results revealed that this 3D CdMOF is more active than the previously reported CdMOFs and, more interestingly, without using a co-catalyst. The catalyst was easily recovered and reused, having the same performance.
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Allamandola, Louis J., Max P. Bernstein, and Scott A. Sandford. "Photochemical Evolution of Interstellar/Precometary Organic Material." International Astronomical Union Colloquium 161 (January 1997): 23–47. http://dx.doi.org/10.1017/s0252921100014585.
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AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.
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Weber, R., A. A. F. Peters, P. P. Breithaupt, and B. M. Visser. "Mathematical Modeling of Swirling Flames of Pulverized Coal: What Can Combustion Engineers Expect From Modeling?" Journal of Fluids Engineering 117, no. 2 (June 1, 1995): 289–97. http://dx.doi.org/10.1115/1.2817143.
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The present study is concerned with mathematical modeling of swirling pulverized coal flames. The attention is focused on the near burner zone properties of high-and low-NOx flames issued from an Aerodynamically Air Staged Burner of 3.4 MW thermal input. The swirling combusting flows are calculated using the k–ε model and second-order models of turbulence. The Eulerian balance equations for enthalpy and mass fractions of oxygen, volatiles, carbon monoxide and final combustion products (CO2 + H2O) are solved. The Lagrangian particle tracking is accompanied by appropriate models of coal devolatilization and char combustion. Nitric oxide emissions are calculated using a NOx post-processor for thermal-, prompt- and fuel-NO. The objective of this paper is to examine whether the engineering information required for designing industrial burners is obtainable through the mathematical modeling. To this end, the flame computations, including NO emissions, are compared with the measured in-flame data. The guidelines as to the combination of physical submodels and model parameters needed for quality predictions of different flame types are given. The paper is a shorter version of our recent ASME publication (Weber et al., 1993).
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Yang, Shiqiao, Ming Lei, Min Li, Chao Liu, Beichen Xue, and Rui Xiao. "Comprehensive Estimation of Combustion Behavior and Thermochemical Structure Evolution of Four Typical Industrial Polymeric Wastes." Energies 15, no. 7 (March 28, 2022): 2487. http://dx.doi.org/10.3390/en15072487.
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A huge amount of industrial waste will be generated during the industrialization process and their harmless disposal has always been a headache for reducing carbon emissions. In this study, the combustion behaviors and thermal kinetics of four typical industrial polymeric wastes including rubber, leather, plastic and cloth, were systematically studied by using a Thermogravimetric Analysis. The gas emission and structural evolution was comprehensively analyzed using TG-FTIR, 2D-PCIS, ICP and TEM. The results show that the combustibility of leather and cloth are better than the other two samples, while the rubber and plastic have a wider combustion temperature range for higher content of C-H bonds and, the intermediate oxidation process and the stubborn cracking process of C=C bonds. The surface reaction was considered to be the main reaction of rubber and plastic (pre-exponential factor less than 10−9), while both leather and cloth went through a complex procedure during multiple decomposition. The volatiles products are gases (e.g., CO2, CH4) and small molecules (e.g., H2O). The high levels of basic metals in the industrial waste causes serious slagging and fouling tendency (fouling index higher than 4.0), which have a serious adverse influence on the operation of a waste incineration plant.
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Korus, Agnieszka, Juan-Pablo Gutierrez, Andrzej Szlęk, Jacek Jagiello, and Andreas Hornung. "Pore development during CO2 and H2O activation associated with the catalytic role of inherent inorganics in sewage sludge char and its performance during the reforming of volatiles." Chemical Engineering Journal 446 (October 2022): 137298. http://dx.doi.org/10.1016/j.cej.2022.137298.
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Wang, Haiyang S., Charles H. Lineweaver, Sascha P. Quanz, Stephen J. Mojzsis, Trevor R. Ireland, Paolo A. Sossi, Fabian Seidler, and Thierry Morel. "A Model Earth-sized Planet in the Habitable Zone of α Centauri A/B." Astrophysical Journal 927, no. 2 (March 1, 2022): 134. http://dx.doi.org/10.3847/1538-4357/ac4e8c.
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Abstract The bulk chemical composition and interior structure of rocky exoplanets are fundamentally important to understand their long-term evolution and potential habitability. Observations of the chemical compositions of solar system rocky bodies and of other planetary systems have increasingly shown a concordant picture that the chemical composition of rocky planets reflects that of their host stars for refractory elements, whereas this expression breaks down for volatiles. This behavior is explained by devolatilization during planetary formation and early evolution. Here we apply a devolatilization model calibrated with solar system bodies to the chemical composition of our nearest Sun-like stars—α Centauri A and B—to estimate the bulk composition of any habitable-zone rocky planet in this binary system (“α-Cen-Earth”). Through further modeling of likely planetary interiors and early atmospheres, we find that, compared to Earth, such a planet is expected to have (i) a reduced (primitive) mantle that is similarly dominated by silicates, albeit enriched in carbon-bearing species (graphite/diamond); (ii) a slightly larger iron core, with a core mass fraction of 38.4 − 5.1 + 4.7 wt% (see Earth’s 32.5 ± 0.3 wt%); (iii) an equivalent water-storage capacity; and (iv) a CO2–CH4–H2O-dominated early atmosphere that resembles that of Archean Earth. Further taking into account its ∼25% lower intrinsic radiogenic heating from long-lived radionuclides, an ancient α-Cen-Earth (∼1.5–2.5 Gyr older than Earth) is expected to have less efficient mantle convection and planetary resurfacing, with a potentially prolonged history of stagnant-lid regimes.
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Puris, Eriks M., and Stephen M. Wickham. "Quantification of lower crustal synmetamorphic fluid fluxes in the Kapuskasing structural zone based on oxygen-isotope profiles across two paragneiss – mafic gneiss contacts." Canadian Journal of Earth Sciences 31, no. 7 (July 1, 1994): 1122–33. http://dx.doi.org/10.1139/e94-100.
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Detailed oxygen-isotope profiles were measured across two very similar amphibolite-grade, paragneiss – mafic gneiss contacts located 2 km apart within the Kapuskasing structural zone. The first profile is asymmetrical about die contact. δ18O values for whole rocks and minerals are homogeneous in the paragneiss (whole-rock δ18O = +10.4 to +11.4‰), smoothly decrease by about 2‰ over 2.5 m moving into the mafic gneiss, and are homogeneous in the remainder of the mafic gneiss (whole-rock δ18O = +7.0 to +7.4‰). The second profile is flat, with homogeneous whole-rock and mineral δ18O values in bom lithologies, and mafic gneiss values (whole-rock δ18O = +8.7 to +9.8‰) that are higher by about 3‰ relative to typical mafic gneiss values. Mineral–mineral isotopic fractioations are fairly constant in all samples and are typical of high-grade metamorphic rocks. Despite their differences, both profiles can be explained by the advection of a mixed H2O–CO2 fluid in equilibrium with the paragneiss across the contact into the mafic gneiss, coupled with diffusion of oxygen in the fluid. Modeling constrains the net fluid flux required to form me first profile to be 1–3 m3/m2, and for me second profile to be ≥ 10 m3/m2. Thus the net fluid flux during metamorphism varied probably by at least a factor of five over 2 km. These fluxes could have been generated locally within the Kapuskasing structural zone during metamorphism either by metamorphic devolatilization reactions or by the release of volatiles from crystallizing magmas.
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Notsu, Shota, Kazumasa Ohno, Takahiro Ueda, Catherine Walsh, Christian Eistrup, and Hideko Nomura. "The Molecular Composition of Shadowed Proto-solar Disk Midplanes Beyond the Water Snowline." Astrophysical Journal 936, no. 2 (September 1, 2022): 188. http://dx.doi.org/10.3847/1538-4357/ac87fa.
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Abstract The disk midplane temperature is potentially affected by the dust traps/rings. The dust depletion beyond the water snowline will cast a shadow. In this study, we adopt a detailed gas-grain chemical reaction network, and investigate the radial gas and ice abundance distributions of dominant carbon-, oxygen-, and nitrogen-bearing molecules in disks with shadow structures beyond the water snowline around a proto-solar-like star. In shadowed disks, the dust grains at r ∼ 3–8 au are predicted to have more than ∼5–10 times the amount of ices of organic molecules such as H2CO, CH3OH, and NH2CHO, saturated hydrocarbon ices such as CH4 and C2H6, in addition to H2O, CO, CO2, NH3, N2, and HCN ices, compared with those in non-shadowed disks. In the shadowed regions, we find that hydrogenation (especially of CO ice) is the dominant formation mechanism of complex organic molecules. The gas-phase N/O ratios show much larger spatial variations than the gas-phase C/O ratios; thus, the N/O ratio is predicted to be a useful tracer of the shadowed region. N2H+ line emission is a potential tracer of the shadowed region. We conclude that a shadowed region allows for the recondensation of key volatiles onto dust grains, provides a region of chemical enrichment of ices that is much closer to the star than within a non-shadowed disk, and may explain to some degree the trapping of O2 ice in dust grains that formed comet 67P/Churyumov-Gerasimenko. We discuss that, if formed in a shadowed disk, Jupiter does not need to have migrated vast distances.
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Frezzotti, Maria Luce, Simona Ferrando, Angelo Peccerillo, Maurizio Petrelli, Francesca Tecce, and Andrea Perucchi. "Chlorine-rich metasomatic H2O–CO2 fluids in amphibole-bearing peridotites from Injibara (Lake Tana region, Ethiopian plateau): Nature and evolution of volatiles in the mantle of a region of continental flood basalts." Geochimica et Cosmochimica Acta 74, no. 10 (May 2010): 3023–39. http://dx.doi.org/10.1016/j.gca.2010.02.007.
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LEROUX, P., S. SHIREY, E. HAURI, M. PERFIT, and J. BENDER. "The effects of variable sources, processes and contaminants on the composition of northern EPR MORB (8–10°N and 12–14°N): Evidence from volatiles (H2O, CO2, S) and halogens (F, Cl)." Earth and Planetary Science Letters 251, no. 3-4 (November 15, 2006): 209–31. http://dx.doi.org/10.1016/j.epsl.2006.09.012.
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Godolt, Mareike, Nicola Tosi, Barbara Stracke, John Lee Grenfell, Thomas Ruedas, Tilman Spohn, and Heike Rauer. "The habitability of stagnant-lid Earths around dwarf stars." Astronomy & Astrophysics 625 (April 30, 2019): A12. http://dx.doi.org/10.1051/0004-6361/201834658.
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Context. The habitability of a planet depends on various factors, such as the delivery of water during its formation, the co-evolution of the interior and the atmosphere, and the stellar irradiation which changes in time. Aims. Since an unknown number of rocky extrasolar planets may operate in a one-plate convective regime, i.e. without plate tectonics, our aim is to understand the conditions under which planets in such a stagnant-lid regime may support habitable surface conditions. Understanding the interaction of the planetary interior and outgassing of volatiles in combination with the evolution of the host star is crucial to determining the potential habitability. M-dwarf stars in particular possess a high-luminosity pre-main sequence phase that endangers the habitability of planets around them via water loss. We therefore explore the potential of secondary outgassing from the planetary interior to rebuild a water reservoir allowing for habitability at a later stage. Methods. We compute the boundaries of the habitable zone around M-, K-, G-, and F-dwarf stars using a 1D cloud-free radiative-convective climate model accounting for the outgassing history of CO2 and H2O from an interior evolution and outgassing model for different interior compositions and stellar luminosity evolutions. Results. The outer edge of the habitable zone strongly depends on the amount of CO2 outgassed from the interior, while the inner edge is mainly determined via the stellar irradiation, as soon as a sufficiently large water reservoir has been outgassed. A build-up of a secondary surface and atmospheric water reservoir for planets around M-dwarf stars is possible even after severe water loss during the high-luminosity pre-main sequence phase as long as some water has been retained within the mantle. For small mantle water reservoirs, between 62 and 125 ppm, a time delay in outgassing from the interior permits such a secondary water reservoir build-up especially for early and mid-M dwarfs because their pre-main sequence lifetimes are shorter than the outgassing timescale. Conclusions. We show that Earth-like stagnant-lid planets allow for habitable surface conditions within a continuous habitable zone that is dependent on interior composition. Secondary outgassing from the interior may allow for habitability of planets around M-dwarf stars after severe water loss during the high-luminosity pre-main sequence phase by rebuilding a surface water reservoir.
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Bower, Dan J., Daniel Kitzmann, Aaron S. Wolf, Patrick Sanan, Caroline Dorn, and Apurva V. Oza. "Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations." Astronomy & Astrophysics 631 (November 2019): A103. http://dx.doi.org/10.1051/0004-6361/201935710.
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Context. A terrestrial planet is molten during formation and may remain molten due to intense insolation or tidal forces. Observations favour the detection and characterisation of hot planets, potentially with large outgassed atmospheres. Aims. We aim to determine the radius of hot Earth-like planets with large outgassing atmospheres. Our goal is to explore the differences between molten and solid silicate planets on the mass–radius relationship and transmission and emission spectra. Methods. An interior–atmosphere model was combined with static structure calculations to track the evolving radius of a hot rocky planet that outgasses CO2 and H2O. We generated synthetic emission and transmission spectra for CO2 and H2O dominated atmospheres. Results. Atmospheres dominated by CO2 suppress the outgassing of H2O to a greater extent than previously realised since previous studies applied an erroneous relationship between volatile mass and partial pressure. We therefore predict that more H2O can be retained by the interior during the later stages of magma ocean crystallisation. Formation of a surface lid can tie the outgassing of H2O to the efficiency of heat transport through the lid, rather than the radiative timescale of the atmosphere. Contraction of the mantle, as it cools from molten to solid, reduces the radius by around 5%, which can partly be offset by the addition of a relatively light species (e.g. H2O versus CO2) to the atmosphere. Conclusions. A molten silicate mantle can increase the radius of a terrestrial planet by around 5% compared to its solid counterpart, or equivalently account for a 13% decrease in bulk density. An outgassing atmosphere can perturb the total radius, according to its composition, notably the abundance of light versus heavy volatile species. Atmospheres of terrestrial planets around M-stars that are dominated by CO2 or H2O can be distinguished by observing facilities with extended wavelength coverage (e.g. JWST).
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Filippov, Sergey V., Anatoly G. Kolosko, and Eugeni O. Popov. "Outgassing during large area field emitter operation in the diode system." Journal of Vacuum Science & Technology B 40, no. 2 (March 2022): 024002. http://dx.doi.org/10.1116/6.0001648.
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We report peculiar emission behavior of large-area cathode based on a multiwalled carbon nanotube/polymer nanocomposite. Mass spectra and kinetics of the partial pressure of the main volatile products released from the surface of the electrodes were obtained when a constant voltage of different levels was applied to the cathode. The main volatile products during field emission diode operation are H2, H2O, CO/C2H4, and CO2. The behavior of H2O peak intensity is characterized by increased inertia relative to sudden voltage changes.
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Salvioli-Mariani, E., L. Toscani, and D. Bersani. "Magmatic evolution of the Gaussberg lamproite (Antarctica): volatile content and glass composition." Mineralogical Magazine 68, no. 1 (February 2004): 83–100. http://dx.doi.org/10.1180/0026461046810173.
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AbstractThe lamproite of Gaussberg is an ultrapotassic rock where leucite, olivine and clinopyroxene microphenocrysts occur in a glass-rich groundmass, containing microliths of leucite, clinopyroxene, apatite, phlogopite and rare K-richterite.Abundant silicate melt inclusions occur in olivine, leucite and, rarely, in clinopyroxene microphenocrysts. Raman investigations on melt inclusions showed the presence of pure CO2 in the shrinkage bubbles. On the other hand, the glass of the groundmass is CO2-poor and contains up to 0.70 wt.% of dissolved H2O, as estimated by infrared spectra. It is inferred that CO2 was released at every stage of evolution of the lamproite magma (CO2-rich shrinkage bubbles), whereas H2O was retained for longer in the liquid. At Gaussberg, CO2 seems to have a major role at relatively high pressure where it favoured the crystallization of H2O-poor microphenocrysts; the uprise of the magma to the surface decreased the solubility of CO2 and caused a relative increase in water activity. As a consequence, phlogopite and K-richterite appeared in the groundmass.The glass composition of both the groundmass and melt inclusions suggests different evolutions for the residual liquids of the investigated samples. Sample G886 shows the typical evolution of a lamproite magma, where the residual liquid evolves toward peralkaline and Na-rich composition and crystallizes K-richterite in the latest stage. Sample G895 derives from mixing/mingling of different batches of magma; effectively glasses from melt inclusions in leucite and clinopyroxene are more alkaline than those found in early crystallized olivine. Leucite and clinopyroxene crystallized early from a relatively more alkaline batch of lamproite magma and, successively, a less alkaline, olivinebearing magma batch assimilated them during its rise to the surface.
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Panina, L. I., E. Yu Rokosova, and M. A. Ryabukha. "Ultrapotassic Aluminosilicate Melts: Specifics of Formation by the Example of Synnyrites from the Synnyr Massif." Russian Geology and Geophysics 63, no. 2 (February 1, 2022): 153–64. http://dx.doi.org/10.2113/rgg20204251.
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Abstract —To reveal the formation conditions of synnyrites in the Synnyr alkaline pluton, we studied melt inclusions in the minerals of shonkinites and pseudoleucite syenites, in apatite segregations in pyroxenites, shonkinites, and synnyrites, and in the minerals of later monchiquite–camptonite dikes. Based on the obtained and earlier published data, a conclusion has been drawn that all plutonic rocks of the massif formed from the same parental alkali-basaltic magma during long-term crystallization differentiation and fractionation in a closed system excluding a release of volatile components. Similar minerals in the rocks crystallized at similar temperatures in the same sequence: clinopyroxene (1280–1150 °C) → leucite (1250–1200 °C) → K-feldspar (1200–1180 °C) → apatite (above 1180–1050 °C) → nepheline and kalsilite. The composition of the parental magma during crystallization evolved toward an increase in Si, Al, and K contents and a decrease in Fe, Mg, and Ca contents, i.e., toward melaphonolite and phonolite melts. The differentiation and fractionation processes led to the separation of minerals according to their specific gravity: Heavy minerals (clinopyroxene, ore minerals, and apatite) descended to the bottom of the magma chamber, forming the lower melanocratic series, and light minerals (leucite, K-feldspar, and foids), together with the residual melt, accumulated in the upper horizons of the chamber, forming the upper leucocratic series of rocks. During crystallization, the amount of fluids increased. At 920–830 °C, the fluids contained 3033–4051 mg/kg CO2, 397–644 mg/kg H2O, and 42.7–83.7 mg/kg CO. At the early high-temperature stage, when the amount of fluids was insignificant, the trend of magma transformation coincided with the trend of basaltoid crystallization. This fact is evidenced by the homogenization temperatures and chemical composition of inclusions in the minerals of monchiquite–camptonites and alkali basaltoids, similar to those in the plutonic rocks of the massif. Clinopyroxene crystallized in dike rocks at 4.58 kbar at a depth of 10–12 km. At the stage of crystallization of feldspars, when the amount of fluids in melts significantly increased during the formation of plutonic rocks and drastically decreased during the formation of basaltoids, the formation trends of these rocks became different. The trend of basaltoid crystallization was directed toward trachyte melts with an increase in Si contents and a decrease in Fe, Mg, Al, and alkali contents. During the formation of plutonic rocks of the massif, the high water pressure prevented the formation of plagioclase, and the melts became more enriched in Al and K and acquired a high-alumina ultrapotassic composition, forming kalsilite–nepheline–K-feldspar synnyrites at the final stages of transformation. A conclusion has been drawn that synnyrites crystallized from the residual products of differentiation and fractionation of alkali-basaltic magma in the temperature range slightly above 1050–1180 °C in a closed system excluding a release of volatiles. The occasional occurrence of synnyrites is due to the limited natural occurrence of closed magma chambers, macroanalogs of inclusions of mineral-forming media in minerals.
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Lages, Joao, Yves Moussallam, Philipson Bani, Nial Peters, Alessandro Aiuppa, Marcello Bitetto, and Gaetano Giudice. "First In-Situ Measurements of Plume Chemistry at Mount Garet Volcano, Island of Gaua (Vanuatu)." Applied Sciences 10, no. 20 (October 19, 2020): 7293. http://dx.doi.org/10.3390/app10207293.
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Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 ± 11.6, 1.8 ± 0.5, 2.0 ± 0.01, 0.26 ± 0.02 and 0.06 ± 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d−1 for Mt. Garet, we estimate a total volatile output of about 6482 t d−1 (CO2 ~259 t d−1; H2O ~5758 t d−1; H2S ~30 t d−1; H2 ~0.5 t d−1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.
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Lakshmanan, Venkatesan, Yi-Ting Lai, Xiang-Kai Yang, Manivannan Govindaraj, Chia-Her Lin, and Jhy-Der Chen. "Eight-Fold Interpenetrating Diamondoid Coordination Polymers for Sensing Volatile Organic Compounds and Metal Ions." Polymers 13, no. 18 (September 7, 2021): 3018. http://dx.doi.org/10.3390/polym13183018.
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Reactions of divalent metal salts with 4,4-oxybis(N-(pyridine-4-yl)-benzamide), L, and naphthalene-1,4-dicarboxylic acid (1,4-H2NDC) in various solvents gave [Zn(L)(1,4-NDC)·H2O]n, 1, [Cd(L)(1,4-NDC)(H2O)·MeOH]n, 2, and [Co(L)(1,4-NDC)(H2O)0.5·MeOH]n, 3, which have been structurally characterized. Complexes 1–3 show eight-fold interpenetrating frameworks with the dia topology, which exhibit porosities substantiated by CO2 adsorption, whereas 1 and 2 manifest stability in aqueous environments and show high selectivity toward sensing of mesitylene molecules and Fe3+ ions with low detection limits and good reusability up to five cycles.
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Goodwin-Bell, Jo-Anne S. "Delineation of isograds in siliceous dolomitic marbles along the Sharbot Lake – Frontenac terrane boundary of the Grenville Province, southeastern Ontario." Canadian Journal of Earth Sciences 45, no. 6 (June 2008): 669–91. http://dx.doi.org/10.1139/e08-017.
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This study presents details of the mineralogy and petrology of siliceous, dolomitic marbles of the Sharbot Lake domain along the Frontenac terrane boundary in the Grenville Province of southeastern Ontario. The location of four mineral isograds in the marble and the related univariant reactions were identified in the Almonte – Carleton Place area. Delineation of the isograds is based on detailed mapping, petrographic analysis of coexisting mineral assemblages, and a polybaric T–XCO2 diagram calculated using thermobarometric data from associated gneissic rocks, where T is temperature and X is fluid composition. The T–X section is based on a field gradient of 32 °C/km. The isograds correspond to the first appearance of tremolite (5 dolomite + 8 quartz + H2O = tremolite + 3 calcite + 7 CO2), diopside (tremolite + 3 calcite + 2 quartz = 5 diopside + 3 CO2 + H2O), diopside + dolomite (tremolite + 3 calcite = dolomite + 4 diopside + H2O + CO2), and forsterite (diopside + 3 dolomite = 2 forsterite + 4 calcite + 5 CO2). Mineral assemblages above and below each isograd are described and relevant examples are shown. Results of this study are consistent with a mixed volatile fluid of a uniform composition during mid- to upper amphibolite-facies metamorphism.
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Bower, Dan J., Kaustubh Hakim, Paolo A. Sossi, and Patrick Sanan. "Retention of Water in Terrestrial Magma Oceans and Carbon-rich Early Atmospheres." Planetary Science Journal 3, no. 4 (April 1, 2022): 93. http://dx.doi.org/10.3847/psj/ac5fb1.
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Abstract Massive steam and CO2 atmospheres have been proposed for magma ocean outgassing of Earth and terrestrial planets. Yet formation of such atmospheres depends on volatile exchange with the molten interior, governed by volatile solubilities and redox reactions. We determine the evolution of magma ocean–atmosphere systems for a range of oxygen fugacities, C/H ratios, and hydrogen budgets that include redox reactions for hydrogen (H2–H2O), carbon (CO–CO2), methane (CH4), and solubility laws for H2O and CO2. We find that small initial budgets of hydrogen, high C/H ratios, and oxidizing conditions suppress outgassing of hydrogen until the late stage of magma ocean crystallization. Hence, early atmospheres in equilibrium with magma oceans are dominantly carbon-rich, and specifically CO-rich except at the most oxidizing conditions. The high solubility of H2O limits its outgassing to melt fractions below ∼30%, the fraction at which the mantle transitions from vigorous to sluggish convection with melt percolation. Sluggish melt percolation could enable a surface lid to form, trapping water in the interior and thereby maintaining a carbon-rich atmosphere (equilibrium crystallization). Alternatively, efficient crystal settling could maintain a molten surface, promoting a transition to a water-rich atmosphere (fractional crystallization). However, additional processes, including melt trapping and H dissolution in crystallizing minerals, further conspire to limit the extent of H outgassing, even for fractional crystallization. Hence, much of the water delivered to planets during their accretion can be safely harbored in their interiors during the magma ocean stage, particularly at oxidizing conditions.
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Bower, Dan J., Kaustubh Hakim, Paolo A. Sossi, and Patrick Sanan. "Retention of Water in Terrestrial Magma Oceans and Carbon-rich Early Atmospheres." Planetary Science Journal 3, no. 4 (April 1, 2022): 93. http://dx.doi.org/10.3847/psj/ac5fb1.
Full textAbstract:
Abstract Massive steam and CO2 atmospheres have been proposed for magma ocean outgassing of Earth and terrestrial planets. Yet formation of such atmospheres depends on volatile exchange with the molten interior, governed by volatile solubilities and redox reactions. We determine the evolution of magma ocean–atmosphere systems for a range of oxygen fugacities, C/H ratios, and hydrogen budgets that include redox reactions for hydrogen (H2–H2O), carbon (CO–CO2), methane (CH4), and solubility laws for H2O and CO2. We find that small initial budgets of hydrogen, high C/H ratios, and oxidizing conditions suppress outgassing of hydrogen until the late stage of magma ocean crystallization. Hence, early atmospheres in equilibrium with magma oceans are dominantly carbon-rich, and specifically CO-rich except at the most oxidizing conditions. The high solubility of H2O limits its outgassing to melt fractions below ∼30%, the fraction at which the mantle transitions from vigorous to sluggish convection with melt percolation. Sluggish melt percolation could enable a surface lid to form, trapping water in the interior and thereby maintaining a carbon-rich atmosphere (equilibrium crystallization). Alternatively, efficient crystal settling could maintain a molten surface, promoting a transition to a water-rich atmosphere (fractional crystallization). However, additional processes, including melt trapping and H dissolution in crystallizing minerals, further conspire to limit the extent of H outgassing, even for fractional crystallization. Hence, much of the water delivered to planets during their accretion can be safely harbored in their interiors during the magma ocean stage, particularly at oxidizing conditions.
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Seligman, Darryl Z., Leslie A. Rogers, Samuel H. C. Cabot, John W. Noonan, Theodore Kareta, Kathleen E. Mandt, Fred Ciesla, et al. "The Volatile Carbon-to-oxygen Ratio as a Tracer for the Formation Locations of Interstellar Comets." Planetary Science Journal 3, no. 7 (July 1, 2022): 150. http://dx.doi.org/10.3847/psj/ac75b5.
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Abstract Based on the occurrence rates implied by the discoveries of 1I/‘Oumuamua and 2I/Borisov, the forthcoming Rubin Observatory Legacy Survey of Space and Time (LSST) should detect ≥one interstellar object every year. We advocate for future measurements of the production rates of H2O, CO2, and CO in these objects to estimate their carbon-to-oxygen ratios, which trace formation locations within their original protoplanetary disks. We review similar measurements for solar system comets, which indicate formation interior to the CO snow line. By quantifying the relative processing in the interstellar medium and solar system, we estimate that production rates will not be representative of primordial compositions for the majority of interstellar comets. Preferential desorption of CO and CO2 relative to H2O in the interstellar medium implies that measured C/O ratios represent lower limits on the primordial ratios. Specifically, production rate ratios of Q(CO)/Q(H2O) < 0.2 and Q(CO)/Q(H2O) > 1 likely indicate formation interior and exterior to the CO snow line, respectively. The high C/O ratio of 2I/Borisov implies that it formed exterior to the CO snow line. We provide an overview of the currently operational facilities capable of obtaining these measurements that will constrain the fraction of ejected comets that formed exterior to the CO snow line. This fraction will provide key insights into the efficiency of and mechanisms for cometary ejection in exoplanetary systems.
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Fu, Dian Zheng, Ye Tang, Zheng Hui Fu, Hong Liang Zhang, and Wei Li. "Study on Volatile Evolution during the Eucalyptus Pyrolysis by Using TG-FTIR Analysis." Advanced Materials Research 884-885 (January 2014): 148–53. http://dx.doi.org/10.4028/www.scientific.net/amr.884-885.148.
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In this study, thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) was used to studying the volatile evolution characteristic during the eucalyptus pyrolysis from South China. The thermogravimetric analysis results indicate that the pyrolysis of eucalyptus occurred in three main stages which are the moisture vaporization stage, the volatile matter release stage and the char decomposition stage. The major gases evolved during the pyrolysis process were identified to be H2O, CO, CO2, CH4. In addition, the effects of different heating rates on the emissions of these pyrolysis products have been studied.
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Freundt, A., I. Grevemeyer, W. Rabbel, T. H. Hansteen, C. Hensen, H. Wehrmann, S. Kutterolf, R. Halama, and M. Frische. "Volatile (H2O, CO2, Cl, S) budget of the Central American subduction zone." International Journal of Earth Sciences 103, no. 7 (February 9, 2014): 2101–27. http://dx.doi.org/10.1007/s00531-014-1001-1.
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Harley, Simon L., and P. Thompson. "The influence of cordierite on melting and mineral-melt equilibria in ultra-high-temperature metamorphism." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 95, no. 1-2 (March 2004): 87–98. http://dx.doi.org/10.1017/s0263593300000948.
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ABSTRACTExperimentally constrained calibrations of the incorporation of H2 O and CO2 into cordierite as functions of P–T-aH2O-aCO2 are integrated with KFMASH grids which define mineral-melt equilibria in pelites. This is used to explore the impact of the volatile content and composition of cordierite on anatexis and melt-related processes in high-temperature (HT) and ultra-high-temperature (UHT) metamorphism. The strongly temperature-sensitive H2O content of cordierite coexisting with dehydration melts (0·4–1·6 wt.%) causes a 10–25% relative decrease in the amount of melt produced from pelites compared with models which treat cordierite as anhydrous.KFMASH melting grids quantified for aH2O demonstrate consistency between the measured H2O contents in cordierite from granulite-migmatite terrains and mineral equilibria. These indicate anatexis with aH2O in the range 0·26–0·16 at 6–8 kbar and 870–930°C. The pressure-stability of cordierite+garnet with respect to orthopyroxene+sillimanite+quartz in KFMASH is strongly influenced by cordierite H2O content, which decreases from 1·1 to 0·5 wt.% along the melting reaction Grt+CrdH+Kfs=Opx+Sil+Qz+L. The lower-T invariant point involving biotite (8·8 kbar/900°C) that terminates this reaction has aH2O of 0·16±0·03, whereas the higher-T terminating invariant point involving osumilite (7·9 kbar/940°C) occurs at aH2O 0·08±0·02. Osumilite-bearing assemblages in UHT terrains imply aH2O of <0·08, and at 950–1000°C and 8–9 kbar calculated aH2O is only 0·04–0·02. Cordierites stable in osumilite-bearing assemblages or with sapphirine+quartz have maximum predicted H2O contents of ca. 0·2 wt.%, consistent with H2O measured in cordierites from two sapphirine-bearing UHT samples from the Napier Complex.The addition of CO2to the H2O-undersaturated (dehydration-melting) system marginally decreases the temperature of melting because of the stabilisation of cordierite, the solid product of the peritectic melting reactions. The preferential incorporation of CO2 enhances the stability of cordierite, even at fixed aH2O, and causes the stability fields of Grt+Crd+Sil+Kfs+Qz+L and Grt+Opx+Crd+Kfs+Qz+L to expand to higher pressure, and to both higher and lower temperatures. The minimum solubility of H2O in granitic melt is independent of the CO2 content of cordierite, and the distribution of H2O between melt and cordierite is similar at a given melt H2O-content to the H2O-only system. This enhanced stability of CO2-bearing cordierite leads to a reduced stability range for osumilite-bearing assemblages to temperatures of ca. 950–975°C or greater. Cordierites in the Napier Complex UHT gneisses contain 0·5 and 1·05 wt.% CO2, consistent with a role for CO2 in stabilising cordierite with respect to osumilite in these unusual sapphirine-bearing granul