Chemical composition of Mars

The composition of Mars has been calculated from the cosmochemical model of Ganapathy and Anders (1974) which assumes that planets and chondrites underwent the same 4 fractionation processes in the solar nebula. Because elements of similar volatility stay together in these processes, only 4 index elements (U, Fe, K and Tl or Ar³⁶) are needed to calculate the abundances of all 83 elements in the planet. The values chosen are U = 28 ppb, K = 62 ppm (based on $\text{K}\text{U}\text{= 2200}$ from orbital γ-spectrometry and on thermal history calculations by Toksöz and Hsui (1978) Fe = 26.72% (from geophysical data), and Tl = 0.14 ppb (from the Ar³⁶ and Ar⁴⁰ abundances measured by Viking).The mantle of Mars is an iron-rich [Mg/(Mg + Fe) = 0.77] garnet wehrlite (ρ = 3.52?3.54 g/cm³), similar to McGetchin and Smyth's (1978) estimate but containing more Ca and Al. It is nearly identical to the bulk Moon composition of Morgan et al. (1978b). The core makes up 0.19 of the planet and contains 3.5% S—much less than estimated by other models. Volatiles have nearly Moon-like abundances, being depleted relative to the Earth by factors of 0.36 (K-group, T_cond = 600–1300 K) or 0.029 (Tl group, T_cond < 600 K). The water abundance corresponds to a 9 m layer, but could be higher by as much as a factor of 11.Comparison of model compositions for 5 differentiated planets (Earth, Venus, Mars, Moon, and eucrite parent body) suggests that volatile depletion correlates mainly with size rather than with radial distance from the Sun. However, the relatively high volatile content of shergottites and some chondrites shows that the correlation is not simple; other factors must also be involved.     

Chemical composition and fractionation of the continental crust

A new estimate of the bulk continental crust is reported consisting of 57 percent lower crust (60% felsic and 40% mafic granulites) and 43 percent upper crust. The proportions of crustal units are based on petrological observations (Bohlen &Mezger, 1989). The estimate of a bulk composition is intermediate between andesite and tonalite and is higher in Si, K, Rb, Sr, Zr, Nb, Ba, LREE, Pb, Th concentrations and lower in Mg, Ca, Sc, Mn, Fe than the crustal abundances reported byTaylor &McLennan (1985). Equal chemical composition between the upper crust and the felsic part of the lower crust is attained in balance computations if one restores a fraction of 12.5 percent S-type granite from the upper into the lower crust. An example of water-undersaturated partial melting and separation of a fraction of about 35 percent granitic magma at the conversion from amphibolite-into granulite-facies metasediments has been balanced bySchnetger (1988) in the Ivrea area (N. Italy). The worldwide observed discrepancy between a larger negative Eu anomaly in the upper crust compared with the half as large positive anomaly of the lower crust increasing from the early Precambrian to present has been explained by recycling of Ca-rich restite into the upper mantle. The composition of the Archean crust (example: Greenland) does not differ systematically from the post-Archean crust.

---

Zusammenfassung Die chemische Zusammensetzung der gesamten kontinentalen Kruste, die zu 57% aus der Unterkruste (60% felsische und 40% mafische Granulite) und zu 43% aus Oberkruste besteht, wurde neu ermittelt. Die Proportionen der Krusteneinheiten beruhen auf petrologischen Beobachtungen (Bohlen &Mezger, 1989). Die geschätzte Zusammensetzung der Gesamtkruste liegt zwischen Andesit und Tonalit. Sie ist höher in den Gehalten an Si, K, Rb, Sr, Zr, Nb, Ba, LREE, Pb, Th und niedriger im Mg, Ca, Sc, Mn, Fe als die vonTaylor &McLennan (1985) mitgeteilten mittleren Krustenwerte. Die chemischen Unterschiede zwischen Ober- und Unterkruste werden ausgeglichen, wenn man die Substanz von 12,5% S-Typ-Granit von der Oberkruste abzieht und zur Unterkruste hinzufügt. Als typisches Beispiel der Abtrennung granitischer Partialschmelzen im wasseruntersättigten System wird das der variskischen Metamorphose von Metasedimenten in der Ivreazone (Nord-Italien) angesehen.Schnetger (1988) konnte hier mit einer chemischen Bilanz zeigen, daß die Umwandlung von amphibolitfaziellen zu granulitfaziellen Gesteinen mit dem Verlust von etwa 35% granitischer Schmelze verbunden war. Die negative Eu-Anomalie der Oberkruste ist weltweit doppelt so groß wie die positive Anomalie der Unterkruste. Diese in der Zeit vom Archaikum bis heute vergrößerte Diskrepanz läßt sich nur mit dem Verlust von Ca-reichen Restiten aus der Kruste an den Mantel erklären. Die chemische Zusammensetzung der kontinentalen Kruste hat sich sonst seit dem Archaikum nicht systematisch geändert, wie am Beispiel Grönlands gezeigt wird.

---

Résumé Cette note propose une nouvelle estimation de la composition chimique d'ensemble de la croûte continentale, constituée pour 57% de croûte inférieure (60% de granulites felsiques et 40% de granulites mafiques) et pour 43% de croûte supérieure. Les proportions de ces unités crustales sont basées sur les observations pétrologiques (Bohlen etMezger 1989). La composition d'ensemble proposée est intermédiaire entre celles d'une andésite et d'une tonalite; par rapport aux abondances crustales données parTaylor etMcLennan (1985), les teneurs sont plus élevées en Si, K, Rb, Sr, Zr, Nb, Ba, LEE, Pb, Th et moins élevées en Mg, Ca, Sc, Mn, Fe. Si on tranfère de la croûte supérieure à la croûte inférieure la matière correspondant à 12,5% de granite de type S, la différence de composition entre ces deux croûtes disparaît. Un exemple typique de fusion partielle granitique en système sous-saturé en eau est fourni par le métamorphisme varisque de métasédiments dans la zone d'Ivrée (Italie du Nord). D'après ce bilan chimique établi parSchnetger (1988), le passage des roches du faciès des amphibolites à celui des granulites s'accompagne de la production d'environ 35% de magma granitique. L'anomalie négative en Eu de la croûte supérieure est partout le double de l'anomalie positive de la coûte inférieure. Cette différence, qui s'est accrue depuis l'Archéen jusqu'aujourd'hui, s'explique par le passage de restites riches en Ca dans le manteau supérieur. La composition d'ensemble de la croûte continentale ne s'est toutefois pas modifiée depuis l'Archéen, comme le montre l'exemple du Groenland.

---

, 57% (60% 40% ), -43%. , (Bohlen & Mezger, 1989). . Taylor & McLennan (1985) Si, K, Rb, Sr, Zr, Nb, Ba, LREE, Pb, Th Mg, Ca, Sc, Mn, Fe. , 12,5% S, , . — , , . Schnetger (1988) , 35%. , . , , , , , . , .

     

Chemical composition of stars in the galactic halo

The chemical compositions of the atmospheres of six metal-poor stars are analyzed. Spectra with signal-to-noise ratios of no less than 100 and a resolution of R≈17 000 were obtained using the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The abundances of Li, O, α-process elements (Mg, Si, Ca, Ti), Na, K, Sc, iron-peak elements (Cr, Mn, Fe, Ni, Cu, Zn), and s-process elements (Y, Ba) are derived. The star G251-54 ([Fe/H]=?1.55, T _eff=5541 K, logg=3.58) is deficient in some elements compared to both stars with similar metallicities and the Sun. The atmosphere of G251-54 has the following elemental abundances relative to iron: [O/Fe]=+0.47, [α/Fe]≈?0.3, [Na/Fe]=?0.60, [Sc/Fe]=?0.57, [Cr, Ni, Fe]≈0, [Zn/Fe]=+0.16, [Cu/Fe]=?0.66, [Y/Fe]=?0.70, and [Ba/Fe]=?1.35. The remaining five stars have metallicities in the range ?1.6<[Fe/H]相似文献   

Chemical composition of surface sediments of the White Sea

Contents of major elements in surface sediments of the White Sea were determined by the X-ray fluorescence method. Application of the statistical analysis (principal component method and cluster analysis) made it possible to divide the sediments into more or less homogeneous seven groups with different chemical and grain size compositions. In general, the groups corresponded to sediment lithotypes based on the classification elaborated at the Shirshov Institute of Oceanology, Russian Academy of Sciences. Contents of Si and Al are controlled by the ratio of sand-silt and pelite fractions, while variations in the content of Mn (and Fe in part) are governed by the redistribution of elements in the course of redox processes of early diagenesis.     

Chemical composition of lunar meteorites and the lunar crust

The paper presents the first analyses of major and trace elements in 19 lunar meteorites newly found in Oman. These and literature data were used to assay the composition of highland, mare, and transitional (highland-mare interface) regions of the lunar surface. The databank used in the research comprises data on 44 meteorites weighing 11 kg in total, which likely represent 26 individual falls. Our data demonstrate that the lunar highland crust should be richer in Ca and Al but poorer in mafic and incompatible elements than it was thought based on studying lunar samples and the first orbital data. The Ir concentration in the highland crust and the analysis of lunar crater population suggest that most lunar impactites were formed by a single major impact event, which predetermined the geochemical characteristics of these rocks. Lunar mare regions should be dominated by low-Ti basalts, which are, however, enriched in LREEs compared to those sampled by lunar missions. The typical material of mare-highland interface zones can contain KREEP and magnesian VLT basalts. The composition of the lunar highland crust deduced from the chemistry of lunar meteorites does not contradict the model of the lunar magma ocean, but the average composition of lunar mare meteorites is inconsistent with this concept and suggests assimilation of KREEP material by basaltic magmas. The newly obtained evaluations of the composition of the highland crust confirm that the Moon can be enriched in refractory elements and depleted in volatile and siderophile elements.     

Chemical composition of river particulates in eastern China

A total of 42 aquatic particulate sample:, (suspended matter and < 63 m surficial sediments) was collected from 11 large rivers in eastern China. Contents of both major elements (Al, Si, Ca, Mg, K, Na, Ti, Fe, Mn) and trace elements (Cu, Pb, Zn, Cd, Cr, Co, Ni, V) in the particulate samples were analyzed. The geographic variations of river particulate compositions were studied. The results showed that the Yellow River particulates contained a notably high content of Ca and a low content of Al. Except for the Yellow River, A1 contents in particulates increased from the northern rivers to the southern rivers, while K and Na decreased. Trace elements were relatively enriched in the southern river particulates. The geographic variations seemed to be related to the weathering types and geological background within the river basins. The average composition of river particulates in China was then estimated. Based on the Chinese river data from this paper, as well as on the literature data for other main world rivers, a new estimation of the global average particulate composition was reported. Since the earlier estimations in the literature were not concerned with or at best concerned only with few of the Chinese rivers which contribute a major proportion to the global load of river particulates, this new estimation may be more reasonable.     

Chemical composition of bottled mineral waters in Estonia

Five commercially available in Estonia brands of bottled water have been analysed for 59 chemical elements by ICP-QMS and ICP-AES techniques to assess the quality of domestic mineral waters in scope of the European Groundwater Geochemistry Project initiated by the Geochemistry Expert Group of EuroGeoSurveys. Contents of 9 cations and anions, pH and electrical conductivity (EC) were measured in the bottled mineral waters by IC, titration and photometric methods. The data showed a significant difference between natural undiluted mineral water (Värska Originaal) characterised by the highest values of pH, EC and majority of trace elements studied, and other domestic waters sold in Estonia.     

Chemical composition of fahlores of the Kupol gold - silver deposit

The chemical study shows that the Kupol fahlores are complex compounds with significant variations in their composition and the proportions of their constituent elements. Based on their major-element composition, they are subdivided into 3 species and several inter- and intra-species varieties. This testifies that the fahlores were formed under different physicochemical conditions.     

Chemical composition of Luna 20 soil and rock fragments

Abundances of 22 elements, including 9 rare earth elements (REE), have been determined by ‘monostandard’ instrumental neutron activation analysis of samples from the Luna 20 soil and in 6 rock fragments, including a crystalline rock of highland origin, a breccia of similar composition, a glass and a feldspar grain. The soil appears to have been contaminated with W and Mo. The REE content of the soil is very low, being close to 2.3 times below the level in the Luna 16 soil. Sampling errors, for most elements, are negligible in the case of analyses performed on one or several tens of mg of soil, but they become significant on crystalline rock fragments in the 1–2 mg range.     

Chemical composition of HAL,an isotopically-unusual Allende inclusion

Thirty-seven major, minor and trace elements were determined by INAA and RNAA in samples of hibonite, black rim and portions of friable rim from an unusual Allende inclusion, HAL. The peculiar isotopic, mineralogical and textural properties of HAL are accompanied by very unusual trace element abundances. The most striking feature of the chemistry is the virtual absence of Ce from an inclusion otherwise highly enriched in REE compared to Cl chondrites. HAL is also depleted in Sr, Ba, U, V, Ru, Os and Ir, relative to other refractory elements. Of the lithophile elements determined which are normally considered to be refractory in a gas of solar composition, Sr, Ba, Ce, U and V are the most volatile in oxidizing gases. The distribution of REE between hibonite and rims seems to have been established when hibonite and other refractory minerals were removed at slightly different temperatures from a hot, oxidizing gas in which they previously coexisted as separate grains. On the basis of HAL's chemical and isotopic composition, possible locations for the chemical and mass dependent isotopic fractionation are in ejecta from the low temperature helium-burning zone of a supernova and in the locally oxidizing environment generated by evaporation of interstellar grains of near-chondritic chemical composition.     

Chemical composition and origin of the earth's primitive mantle

An attempt has been made to estimate the chemical composition of the earth's primitive mantle by a critical evaluation of data derived from ultramafic mantle samples and partial melting model calculations for mafic and ultramafic magmas of various ages.Compatible (Al, Ca, Si, Mg, Fe) and moderately incompatible (Ti, Zr, heavy and middle rare earth) elements in basaltic magma sources have not changed significantly since the early Archaean (~3.5 Byr). Estimated abundances for refractory lithophile elements (such as Al, Ca, Ti, Zr, Y, Se, REE etc.) in the primitive mantle are about 2.0 times ordinary chondrites (~ 1.1 times Cl chondrites relative to Mg). Highly incompatible volatile elements (K, Rb, Cs, Tl, Pb etc.) are depleted in the mantle throughout geological time. Abundances of Fe, Ni and Co are obtained on the basis of values for ultramafic nodules and model calculations using komatiites of various ages. The results show little (? 20%?) dispersion and there is no obvious secular variation since 3.5 Byr. Noble metals show similar effects. These data permit constraints to be placed on the timing of core formation.The estimated elemental abundances for the primitive mantle are normalized to Cl chondrites relative to Mg and plotted against the solar condensation temperature at 10^?4 atm. Above 700 K there are two parallel trends which are defined by lithophile elements (Al, Ca, REE, Ti, Mg, Si, Cr, Mn, Na, K, Rb, F, Zn etc.) and siderophile elements (W, Ni, Co, P, As, Ag, Sb and Ge) respectively. The depletion factor for the siderophile trend relative to the lithophile trend is about 0.085. Within each trend there is a continuous depletion towards lower temperature. A third trend is defined by noble metals (Ir, Os, Re, Pd, Pt and Au) with a depletion factor of about 0.003 relative to Cl chondrites. These trends are interpreted in terms of core-mantle differentiation and volatility-controlled processes operating before and during earth accretion.     

Chemical composition of the bottom sediments in the middle reaches of the Amur River

The chemical composition of the bottom sediments of the Amur River has been analyzed using modern analytical techniques. It was found that their composition and distribution patterns are controlled by several sources. The most probable sources for the bottom sediments of the studied area are siliceous magmatic or metasedimentary rocks.     

Chemical composition of planetary nebulae in the Large and Small Magellanic Clouds

The technique of nebular-gas diagnostics was used to find electronic temperatures T _e , concentrations n _e , relative ion concentrations n(A⁺ⁱ )/n(H⁺), and chemical abundances A/H for planetary nebulae in the Large and Small Magellanic Clouds. This analysis took into account inhomogeneities of the nebular-gas density in the nebulae. We determined the pre-galactic helium abundance Y _p and its rate of enrichment dY/dZ for the envelopes of nine nebulae in the Large Magellanic Cloud. Taken together with the Galaxy’s planetary nebulae and HII regions in blue compact dwarf galaxies, Y _p = 0.248 ± 0.002, dY/dZ = 2.31 ± 0.48 and Y _p = 0.247 ± 0.002, dY/dZ = 3.03 ± 0.56, respectively, when macroinhomogeneities and macro/microinhomogeneities of the gas density in galactic nebulae are taken into account.     

太行山金矿成矿流体的成分——显微红外光谱研究

太行山金矿中流体包裹体的显微红外光谱研究表明,金矿成矿流体的化学组成从简单的Ｈ２Ｏ＋ＮａＣｌ、Ｈ２Ｏ＋ＣＯ２、Ｈ２Ｏ＋ＣＯ２＋ＮａＣｌ到复杂的Ｈ２Ｏ＋ＣＯ２＋ＮａＣｌ＋Ｈ２Ｓ＋ＣＨ４和ＣＯ２＋ＣＨ４＋Ｈ２Ｏ＋ＮａＣｌ体系。首次在太行山金矿的单个流体包裹体中检测到Ｈ２Ｓ和ＣＨ４谱峰对探讨该区成矿流体的演化具有重要理论意义。金矿中存在３类物理性质和化学性质截然不同的流体包裹体,同一梓品中几乎同时出现物     

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).     

Chemical composition of the Tertiary black shales of West Sabah, East Malaysia

The X-ray fluorescence and ICP methods were used to analyze 60 outcrop samples of black shale, of which 15 were collected from Belait, 15 from the Setap Shale, 15 from Temburong, and 15 from the Trusmadi formations. The average compositions of the shales from the study area are 64.62%, 63.95%, 62.32%, 63.84% SiO2, 1.84%, 2.14%, 2.04%, 1.99% MgO, 2.55%, 3.12%, 2.89%, 2.72% K2O, 0.32%, 0.30%, 0.32%, 0.53% CaO, 5.86%, 6.06%, 7.14%, 6.60% Fe2O3, 207×10^-6, 180×10^-6, 213×10^-6, 200×10^-6 Rb, and 56×10^-6, 49×10^-6, 50×10^-6, 32×10^-6 Sr for the Setap Shale, Temburong, Belait and Trusmadi samples, respectively. The high Rb/Sr ratios of 3.8, 3.7, 4.2, and 6.1 are attributed to the lowest contents of Sr due to reducing conditions prevailing. The high Rb/K ratio sug- gests either brackish marine or rapid deposition that prevented equilibrium between Rb and K in the shales and marine waters.     

Chemical composition of gas and grains in dense interstellar clouds

This paper is a short review of the present knowledge on the composition of dense clouds where stars form, with extensions to the less dense interstellar medium and to the most likely sites of grain formation. The problem is complex and intricate, and it is still difficult to answer such fundamental questions as the lifetime of the dense clouds or the lifetime of the interstellar grains.