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Mass Fractions of S,Cu, Se,Mo, Ag,Cd, In,Te, Ba,Sm, W,Tl and Bi in Geological Reference Materials and Selected Carbonaceous Chondrites Determined by Isotope Dilution ICP‐MS 
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下载免费PDF全文 Zaicong Wang Harry Becker Frank Wombacher 《Geostandards and Geoanalytical Research》2015,39(2):185-208
Mass fractions of S, Cu, Se, Mo, Ag, Cd, In, Te, Ba, Sm, W and Tl were determined by isotope dilution sector field ICP‐MS in the same sample aliquot of reference materials using HF‐HNO3 digestion in PFA beakers in pressure bombs and glassy carbon vessels in a high‐pressure asher (HPA‐S) for comparison. Additionally, Bi was determined by internal standardisation relative to Tl. Because isobaric and oxide interferences pose problems for many of these elements, efficient chromatographic separation methods in combination with an Aridus desolvator were employed to minimise interference effects. Repeated digestion and measurement of geological reference materials (BHVO‐1, BHVO‐2, SCo‐1, MAG‐1, MRG‐1 and UB‐N) gave results with < 5% relative intermediate precision (1s) for most elements, except Bi. Replicates of NIST SRM 612 glass digested on a hot plate were analysed by the same methods, and the results agree with reference values mostly within 2% relative deviation. Data for the carbonaceous chondrites Allende, Murchison, Orgueil and Ivuna are also reported. Digestion in a HPA‐S was as efficient as in pressure bombs, but some elements displayed higher blank levels following HPA‐S treatment. Pressure bomb digestion yielded precise data for volatile S, Se and Te, but may result in high blanks for W. 相似文献
2.
Alexander N. Krot Michail I. Petaev Shoichi Itoh Timothy J. Fagan Hisayoshi Yurimoto Michael K. Weisberg Matsumi Komatsu Klaus Keil 《Chemie der Erde / Geochemistry》2004,64(3):185-239
Amoeboid olivine aggregates (AOAs) are the most common type of refractory inclusions in CM, CR, CH, CV, CO, and ungrouped carbonaceous chondrites Acfer 094 and Adelaide; only one AOA was found in the CBb chondrite Hammadah al Hamra 237 and none were observed in the CBa chondrites Bencubbin, Gujba, and Weatherford. In primitive (unaltered and unmetamorphosed) carbonaceous chondrites, AOAs consist of forsterite (Fa<2), Fe, Ni-metal (5-12 wt% Ni), and Ca, Al-rich inclusions (CAIs) composed of Al-diopside, spinel, anorthite, and very rare melilite. Melilite is typically replaced by a fine-grained mixture of spinel, Al-diopside, and ±anorthite; spinel is replaced by anorthite. About 10% of AOAs contain low-Ca pyroxene replacing forsterite. Forsterite and spinel are always 16O-rich (δ17,18O∼−40‰ to −50‰), whereas melilite, anorthite, and diopside could be either similarly 16O-rich or 16O-depleted to varying degrees; the latter is common in AOAs from altered and metamorphosed carbonaceous chondrites such as some CVs and COs. Low-Ca pyroxene is either 16O-rich (δ17,18O∼−40‰) or 16O-poor (δ17,18O∼0‰). Most AOAs in CV chondrites have unfractionated (∼2-10×CI) rare-earth element patterns. AOAs have similar textures, mineralogy and oxygen isotopic compositions to those of forsterite-rich accretionary rims surrounding different types of CAIs (compact and fluffy Type A, Type B, and fine-grained, spinel-rich) in CV and CR chondrites. AOAs in primitive carbonaceous chondrites show no evidence for alteration and thermal metamorphism. Secondary minerals in AOAs from CR, CM, and CO, and CV chondrites are similar to those in chondrules, CAIs, and matrices of their host meteorites and include phyllosilicates, magnetite, carbonates, nepheline, sodalite, grossular, wollastonite, hedenbergite, andradite, and ferrous olivine.Our observations and a thermodynamic analysis suggest that AOAs and forsterite-rich accretionary rims formed in 16O-rich gaseous reservoirs, probably in the CAI-forming region(s), as aggregates of solar nebular condensates originally composed of forsterite, Fe, Ni-metal, and CAIs. Some of the CAIs were melted prior to aggregation into AOAs and experienced formation of Wark-Lovering rims. Before and possibly after the aggregation, melilite and spinel in CAIs reacted with SiO and Mg of the solar nebula gas enriched in 16O to form Al-diopside and anorthite. Forsterite in some AOAs reacted with 16O-enriched SiO gas to form low-Ca pyroxene. Some other AOAs were either reheated in 16O-poor gaseous reservoirs or coated by 16O-depleted pyroxene-rich dust and melted to varying degrees, possibly during chondrule formation. The most extensively melted AOAs experienced oxygen isotope exchange with 16O-poor nebular gas and may have been transformed into magnesian (Type I) chondrules. Secondary mineralization and at least some of the oxygen isotope exchange in AOAs from altered and metamorphosed chondrites must have resulted from alteration in the presence of aqueous solutions after aggregation and lithification of the chondrite parent asteroids. 相似文献
3.
The EH and EL enstatite chondrites are the most reduced chondrite groups, having formed in nebular regions where the gas may
have had high C/O and/or pH2/pH2O ratios. Enstatite chondrites (particularly EH) have higher CI- and Mg-normalized abundances of halogens (especially F and
Cl) and nitrogen than ordinary chondrites and most groups of carbonaceous chondrites. Even relative to CI chondrites, EH and
EL chondrites are enriched in F. We have found that literature values for the halogen abundance ratios in EH and EL chondrites
are strongly correlated with the electronegativities of the individual halogens. We suggest that the most reactive halogens
were the most efficient at forming compounds (e.g., halides) that were incorporated into EH-chondrite precursor materials.
It seems plausible that, under the more-oxidizing conditions pertaining to the other chondrite groups, a larger fraction of
the halogens remained in the gas. Nitrogen may have been incorporated into the enstatite chondrites as simple nitrides that
did not condense under the more-oxidizing conditions in the regions where other chondrite groups formed. Literature data show
that unequilibrated enstatite chondrites have light bulk N (δ 15N ≈ −20‰) compared to most ordinary (−5 to +20‰) and carbonaceous (+20 to +190‰) chondrites; this may reflect the contribution
in enstatite chondrites of nitride condensates with δ15 N values close to the proposed nebular mean (~−400‰). In contrast, N in carbonaceous chondrites is mainly contained within
15N-rich organic matter. The major carrier of N in ordinary chondrites is unknown. 相似文献
4.
Since 1994, the Rumuruti (R) chondrites have been recognized as a new, well-established chondrite group differing from carbonaceous, ordinary, and enstatite chondrites. The first R chondrite, Carlisle Lakes, was found in Australia in 1977. Meanwhile, the number has increased to 107 (December, 2010). This group is named after the Rumuruti meteorite, the first and so far the only R chondrite fall. Most of the R chondrites are breccias containing a variety of different clasts embedded in a clastic matrix. Some textural and mineralogical characteristics can be summarized as follows: (a) the chondrule abundance in large fragments and in unbrecciated rocks is ∼35–50 vol%; (b) Ca,Al-rich inclusions are rare; (c) the olivine abundance is typically 65–78 vol%; (d) the mean chondrule diameter is ∼400 μm; (e) in unequilibrated R chondrites, low-Ca pyroxene is dominating, whereas in equilibrated R chondrites it is Ca-rich pyroxene; (f) the typical olivine in a metamorphosed lithology is ∼Fa38–40; (g) matrix olivine in unequilibrated, type 3 fragments and rocks has much higher Fa (∼45–60 mol%) compared to matrix olivines in type 4–6 lithologies (∼Fa38–41); (h) spinels have a high TiO2 of ∼5 wt%; (i) abundant different noble metal-bearing phases (metals, sulfides, tellurides, arsenides) occur. The exception is the metamorphosed, type 5/6 R chondrite La Paz Icefield 04840 which contains hornblende, phlogopite, and Ca-poor pyroxene, the latter phase typically occurring in low-grade metamorphosed R chondrites only.In bulk composition, R chondrites have some affinity to ordinary chondrites: (a) the absence of significant depletions in Mn and Na in R chondrites and ordinary chondrites is an important feature to distinguish these groups from carbonaceous chondrites; (b) total Fe (∼24 wt%) of R chondrites is between those of H and L chondrites (27.1 and 21.6 wt%, respectively); (c) the average CI/Mg-normalized lithophile element abundances are ∼0.95 × CI, which is lower than those for carbonaceous chondrites (≥1.0 × CI) and slightly higher than those for ordinary chondrites (∼0.9 × CI); (d) trace element concentrations such as Zn (∼150 ppm) and Se (∼15 ppm) are much higher than in ordinary chondrites; (e) the whole rock Δ17O of ∼2.7 for R chondrites is the highest among all meteorite groups, and the mean oxygen isotope composition is δ17O = 5.36 ± 0.43, δ18O = 5.07 ± 0.86, Δ17O = +2.72 ± 0.31; (f) noble gas cosmic ray exposure ages of R chondrites range between ∼0.1 and ∼70 Ma. More than half of the R chondrites analyzed for noble gases contain implanted solar wind and, thus, are regolith breccias. The 43 R chondrites from Northern Africa analyzed so far for noble gases seem to represent at least 16 falls. Although the data base is still scarce, the data hint at a major collision event on the R chondrite parent body between 15 and 25 Ma ago. 相似文献
5.
We use a simple model of the formation, growth, coalescence and migration of veins of basaltic melt generated by partial melting in chondritic asteroids to deduce the sizes of, and pressures within, the fluid-filled dikes reaching the surfaces of such bodies. The gas contents ( 1000 ppm of mainly CO and N2) of the asteroids were high enough that bubbles of free gas trapped in the melt veins gave the basaltic melts significant buoyancy; expansion of these gases as a dike opened to the vacuum at the surface led to fragmentation of the melts into liquid droplets which were transported upwards by the accelerating gases to the surface. The sizes of these droplets and, hence, of the pyroclastic glass beads into which they cooled, are calculated to lie in the range 30 μm to 4 mm; this range is essentially independent of the size or gas content of the asteroid parent and only weakly dependent on the internal pressure of the erupting fluid. The fate of the pyroclasts, however, does depend on all of these factors. At very low internal pressures, significant separation of the gas and liquid in a rising dike may take place and not all of the liquid will be expelled from the dike when it opens to the surface. For relatively large ( 100 km radius) asteroids with relatively low ( 300 ppm) gas contents, the larger clasts are too heavy to be lifted from the level at which magma fragmentation takes place by the gas flow and so would also remain behind to form basaltic veins. The apparent absence of basaltic veins in meteorites then implies both that internal pressures in near-surface dikes were generally greater than 0.3 MPa and that low gas contents were not common. Finally, as long as pyroclasts are lofted from the magma fragmentation level, they will be accelerated to at least 90% of the final gas speed. If this speed exceeds the escape speed from the asteroid (as happens readily for high gas contents and small asteroids), the pyroclasts will be expelled into space and lost from the meteorite record. Otherwise (low gas contents or large asteroids), they will eventually fall back to be incorporated into the surface regolith, modifying the chemical and physical properties of meteorites subsequently derived from it. 相似文献
6.
Mario Trieloff Joachim Kunz Claude J. Allgre 《Earth and Planetary Science Letters》2002,200(3-4):297-313
New noble gas data of ultramafic xenoliths from Réunion Island, Indian Ocean, further constrain the characteristics of primordial and radiogenic noble gases in Earth’s mantle plume reservoirs. The mantle source excess of nucleogenic 21Ne is significantly higher than for the Hawaiian and Icelandic plume reservoirs, similar to excess of radiogenic 4He. 40Ar/36Ar of the Réunion mantle source can be constrained to range between 8000 and 12 000, significant 129Xe and fission Xe excess are present. Regarding the relative contribution of primordial and radiogenic rare gas nuclides, the Réunion mantle source is intermediate between Loihi- and MORB-type reservoirs. This confirms the compositional diversity of plume sources recognized in other radioisotope systematics. Another major result of this study is the identification of the same basic primordial component previously found for the Hawaiian and Icelandic mantle plumes and the MORB reservoir. It is a hybrid of solar-type He and Ne, and ‘atmosphere-like’ or ‘planetary’ Ar, Kr, Xe (Science 288 (2000) 1036). 20Ne/22Ne ratios extend to maximum values close to 12.5 (Ne-B), which is the typical signature of solar neon implanted as solar corpuscular radiation. This suggests that Earth’s solar-type noble gas inventory was acquired by small (less than km-sized) precursor planetesimals that were irradiated by an active early sun in the accretion disk after nebular gas dissipation, or, alternatively, that planetesimals incorporated constituents irradiated in transparent regions of the solar nebula. Previously, such an early irradiation scenario was suggested for carbonaceous chondrites which follow common volatile depletion trends in the sequence CI–CM–CV–Earth. In turn, CV chondrites closely match Earth’s mantle composition in 20Ne/22Ne, 36Ar/22Ne and 36Ar/38Ar. This indicates that mantle Ar could well be a planetary component inherited from precursor planetesimals. However, a corresponding conclusion for mantle Kr and Xe is less convincing yet, but this may be just due to the lack of appropriate ‘meteoritic’ building blocks matching terrestrial composition. Alternatively, heavy noble gases in Earth’s mantle could be due to admixing of severely fractionated air, but this effect must have affected all mantle sources to a very similar extent, e.g. by global subduction before the last homogenization of the mantle reservoirs. 相似文献
7.
本文研究的28块陨石,均为我国第16次南极科学考察队,在南极格罗夫山地区回收。由于样品量有限,每个样品仅有一个光簿片。利用透反两用的偏光显微镜,进行陨石结构,矿物组成等一些现象观察。它们都是石质陨石,有球粒陨石和无球粒陨石。根据球粒发育程度,分为五种类型。用电子探针分析陨石中矿物的化学成份。有两块为无球粒陨石,GRV 99018为钙长辉长无球粒陨石,GRV 99027为橄辉无球粒陨石。利用Dodd(1981)和Wasson(1985)球粒陨石化学群分类原则,将26块普通球粒陨石进行化学群的分类,两者划分的结果基本吻合。前者H群有6块,L群有9块,LL群有8块,另3块陨石近于L群(GRV 99019,GRV 99021,GRV99026)。后者H群有5块,GRV 99010近于L群,它可为H/L,L群有9块,L/LL群有2个,LL群有6块,而GRV 99019,GRV 99021和GRV 99026三块陨石与三个群的数据相差较大,它们属于非平衡球粒陨石,可能是L。26块普通球粒陨石,有5个为非平衡普通球粒陨石,其它21个为平衡球粒陨石。21个平衡普通球粒陨石的岩石类型,主要为4—6。 相似文献
8.
Meteorites are the extraterrestrial rocks, which provide insights into the origin and evolution of the solar system. During the past half century, a great number of meteorites has been discovered on the Antarctic Ice Sheet, confirming that the Antarctica is the most important meteorite concentration area on the earth. Since the first four Antarctic meteorites were found in Grove Mountains in 1998, a total of 9834 meteorites have been collected by four subsequent expeditions. It opens a new field of meteorite study in China, and also accumulates a great deal of scientific samples for China. Recently, classification of Grove Mountains meteorites has been carried out for 6 years, and made following progresses: (1) 2433 meteorites, which include many special meteorites, e.g. Martian meteorites, ureilites and carbonaceous chondrites, have been classified. (2) the Antarctic meteorite curation and the sample sharing system are set up preliminarily. (3) the classification procedure, the management of meteorite samples, and the application procedure for the Antarctic meteorites are completed after the systematic classification during these years. (4) young generation researchers on meteorite are trained through the cooperation of many universities and institutes on meteorite classification. 相似文献
9.
Keilite (Fe>0.5,Mg<0.5)S, the iron-dominant cubic analog of niningerite, (Mg>0.5,Fe<0.5)S, occurs in enstatite chondrites [Shimizu, M., Yoshida, H., Mandarino, J.A., 2002. The new mineral species keilite, (Fe,Mg)S, the iron-dominant analog of niningerite. Can. Mineral. 40, 1687–1692]. I find that keilite occurs only in enstatite chondrite impact-melt rocks and impact-melt breccias. Based on the phase relations in the system MgS–MnS–CaS–FeS [Skinner, B.J., Luce, F.D., 1971. Solid solutions of the type (Ca,Mg,Mn,Fe)S and their use as geothermometers for the enstatite chondrites. Am. Mineral. 56, 1269–1296], I conclude that keilite formed from niningerite or alabandite (Mn>0.5,Fe<0.5)S by reaction with troilite (FeS) at elevated temperatures of well above 500 °C (the lowest equilibration temperature of keilite), but it is likely that the maximum temperatures during melting experienced by keilite-bearing impact-melt rocks and impact-melt breccias were considerably higher, perhaps >1500 °C, as indicted by the occurrence of euhedral enstatite that formed from a melt [McCoy, T.J., Dickinson, T.L., Lofgren, G.E., 1999. Partial melting of the Indarch (EH4) meteorite: a textural, chemical, and phase relations view of melting and melt migration. Meteorit. Planet. Sci. 34, 735–746]. Based on the classifications of the keilite-bearing meteorites as impact-melt rocks and impact-melt breccias and my own textural observations, I conclude that this elevated temperature was reached as a result of impact and not internal heating and melting, followed by fast cooling, thus, quenching in keilite. Enstatite chondrite impact-melt rocks and impact-melt breccias that do not contain keilite may have been more deeply buried after impact and, hence, cooled slowly and were annealed so that FeS exsolved from keilite, concomitant with the formation of niningerite, alabandite or various (Mn,Mg,Fe) mixed sulfides. 相似文献
10.
《Chemie der Erde / Geochemistry》2014,74(3):507-516
New bulk compositional data for 34 Allende chondrules are presented. Whole chondrules were analyzed by instrumental neutron activation analysis (INAA). The new data set is evaluated together with older INAA data on Allende chondrules and recent INAA data on Mokoia chondrules. The Ni/Co ratios of 200 chondrules are close to the CI- or solar ratio. The chondritic Ni/Co ratios require an unfractionated chondritic metal source and set a limit to the fraction of metal lost from molten chondrules. The bulk chondrule Fe/Ni and Fe/Co ratios are more variable but on average chondritic. Iridium and other refractory metals have extremely variable concentrations in chondrules. High Ir chondrules have chondritic Ir/Sc ratios. They are dominated by CAI (Ca,Al-rich inclusion) components. Low Ir chondrules have approximately chondritic Ir/Ni ratios reflecting mixing with chondritic metal. In low Ir chondrules Ir correlates and in high Ir chondrules Ir does not correlate with Ni or Co. A large fraction of Ir may have entered chondrules in variable amounts as tiny grains of refractory metal alloys.Most Allende chondrules have Ir/Sc ratios below bulk meteorite ratios. Matrix must have a complementary high Ir/Sc ratio, as bulk Allende has approximately chondritic Ir/Sc ratio. Similarly, the high average Ir/Ni ratios of Allende chondrules must be balanced by low Ir/Ni ratios in matrix to obtain the bulk Allende Ir/Ni ratio, which is close to the average solar system ratio.More recent data on single chondrules from Allende by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and ICP-OES (Inductively Coupled Optical Emission Spectrometry) show the same trends as the INAA data discussed here. 相似文献