Victor Moritz Goldschmidt (1888–1947): a pictorial tribute

A collection of 34 photographs covering the years 1904–1944 of V. M. Goldschmidt's life is presented. These photographs illustrate the importance of field observations in his scientific investigations. On the personal side they show he was an individual with strong bonds to his colleagues and their families.     

Peculiarities of α-element abundances in Galactic open clusters

A catalog compiling the parameters of 346 open clusters, including their metallicities, positions, ages, and velocities has been composed. The elements of the Galactic orbits for 272 of the clusters have been calculated. Spectroscopic determinations of the relative abundances, [el/Fe], for 14 elements synthesized in various nuclear processes averaged over data from 109 publications are presented for 90 clusters. The compiled data indicate that the relative abundances of primary α elements (oxygen and magnesium) exhibit different dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits in clusters with high, elongated orbits satisfying the criterion (Z_max² + 4e²)^1/2 > 0.40 and in field stars of the Galactic thin disk (Z_max is the maximum distance of the orbit from the Galactic plane in kiloparsec and e is the eccentricity of the Galactic orbit). Since no systematic effects distorting the relative abundances of the studied elements in these clusters have been found, these difference suggest real differences between clusters with high, elongated orbits and field stars. In particular, this supports the earlier conclusion, based on an analysis of the elements of the Galactic orbits, that some clusters formed as a result of interactions between high-velocity,metal-poor clouds and the interstellar mediumof theGalactic thin disk. On average, clusters with high, elongated orbits and metallicities [Fe/H] < -0.1 display lower relative abundances of the primary a elements than do field stars. The low [O, Mg/Fe] ratios of these clusters can be understood if the high-velocity clouds that gave rise to them were formed of interstellar material from regions where the star-formation rate and/or the masses of Type II supernovae were lower than near the Galactic plane. It is also shown that, on average, the relative abundances of the primary a elements are higher in relatively metal-rich clusters with high, elongated orbits than in field stars. This can be understood if clusters with [Fe/H] > -0.1 formed as a result of interactions between metal-rich clouds with intermediate velocities and the interstellar medium of the Galactic disk; such clouds could form from returning gas in a so-called “Galactic fountain.”     

Revised and supplemented data on Gibbs' free energies of substances at the parameters of the Earth's mantle

New (revised) data on thermodynamic properties of 60 substances are calculated by extrapolating their compressibilities and calorific properties up to 4000 K and 1 Mbar. Stability of pyrrhotite throughout the mantle supports Goldschmidt's idea about a sulphide zone between the mantle and the core. Such a zone could serve as a primary source of ores. Volatile H₂O and H₂S are stable throughout the mantle. Some hydrocarbons decompose into a mixture of methane and carbon over a wide range of pressures and temperatures. Natural oil may be regarded as a mixture of metastable hydrocarbons. FeO does not dissociate into a mixture of Fe₂O₃ and Fe at high pressure and temperature. Alkali-free carbonate magmas may arise in the mantle. The greater the proportion of iron-silicates in the mantle, the more probable is the existence of a ferrous-ferric garnet zone at great depth.     

Petrology and geochemistry of the island of Sarigan in the Mariana arc; calc-alkaline volcanism in an oceanic setting

Isotopic studies of rocks from oceanic island arcs such as the Marianas indicate that little, if any, recycling of continental material (e.g. oceanic sediments) occurs in these arcs. Because oceanic arcs are on the average more mafic than the dominantly andesitic continental arcs, an important question is whether the andesites of continental arcs are produced by a fundamentally different (more complex?) mechanism than the lavas of oceanic arcs. An excellent opportunity for study of this question is provided by the island of Sarigan, in the Mariana active arc, on which calc-alkaline andesites (including hornblende-bearing types) are exposed along with more mafic lavas. Available isotope data suggest the Sarigan lavas (including the andesites) were derived from mantle material with little or no involvement of continental components. Ratios of incompatible elements suggest that most of the Sarigan lavas were derived from similar source materials. Absolute abundances of incompatible elements vary irregularly within the eruptive sequence and indicate at least 5 distinct magma batches are represented on Sarigan. Major element data obtained on the lavas and mineral phases in them, combined with modal mineral abundances, suggest that the calc-alkaline nature of the volcanic rocks on Sarigan results from the fractional crystallization of titanomagnetite in combination with other anhydrous phases. Amphibole, although present in some samples, is mainly a late-crystallizing phase and did not produce the calc-alkline characteristics of these lavas. Gabbroic samples found in the volcanic sequence have mineralogc and geochemical characteristics that would be expected of residual solids produced during fractional crystallization of the Sarigan lavas. When combined, data on the lavas and the gabbros suggest the following crystallization sequence: olivine — plagioclase — clinopyroxene — titanomagnetite — orthopyroxene±hornblende, biotite and accessory phases. These results lead to the conclusion that calc-alkaline magmas can be generated directly from mantle sources.     

Abundances of chemical elements in the Earth’s crust

The evaluation of the abundances of chemical elements in the Earth’s crust is a pivotal geochemical problem. Its first solutions in the early 20th century formed the empirical groundwork for geochemistry and justified concepts about the unity of the material of the Universe, the genesis of the chemical elements, and the geochemical differentiation of the Earth. The accumulation of newly obtained data called for the revision of this problem, and a series of papers by A.P. Vinogradov, which were published in Geokhimiya in 1956–1962, presented reevaluated contents of elements in the continental crust. In these papers, A.P. Vinogradov relied on the classic idea of the geochemical balance of the sedimentary process. These generalizations provided the foundation for the quantitative characterization of the geochemical background of the biosphere and allowed Vinogradov to formulate the principles of the melting and degassing of material in the outer Earth’s shells during the geologic history, a concept that became universally acknowledged in modern geochemistry and geology. The composition of the Earth’s crust can also be evaluated based not on the principle of geochemical balance in the sedimentary process but on data on the actual abundances of major magmatic, metamorphic, and sedimentary rock types. The possibility of this solution was provided after the extensive research of A.B. Ronov, who managed to develop a quantitative model for the structure of the Earth’s sedimentary shell. Based on these data, A.B. Ronov, A.A. Yaroshevsky, and A.A. Migdisov published a series of papers in Geokhimiya in 1967–1985 that presented a model for the chemical structure of the Earth’s crust with regard for the material composing not only the upper part of the continental crust but also its deep-seated granulite-basite layer and the oceanic crust. The quantitative estimates thus obtained led the authors to important conclusions: first, it was demonstrated that the estimated abundances of elements in the granite-metamorphic layer of the continental crust presented in the classic works by A.P. Vinogradov are confirmed by independent materials, which are based on data on the actual abundance of rocks. Second, incredible as it was, the principle of geochemical balance in the sedimentary process in application to Ca and carbonates appeared to be invalid. This problem remains unsettled as of yet and awaits its resolution.     

Geochemical signature of provenance in sand-size material in soils and stream sediments near the Tobacco Root batholith, Montana, U.S.A.

Trace-element geochemistry of sandstones are being used to determine provenance. We have conducted preliminary and limited experiments to determine to what extent daughter sands retain the geochemical signature of parent rocks. Six sets of first-order stream sediments, soils from adjacent slopes, and a variety of parent rocks were collected from southwestern Montana, U.S.A. Sampling in a low-relief area ensured that climate and residence time of soils on slopes could be eliminated as variables. Sand-size fractions of stream sediments and soils, and the corresponding parent rocks (granodiorite, quartz monzonite, granite gneiss, biotite-tonalite gneiss and amphibolite) were analyzed for most major elements and selected trace elements. Petrologic modal analysis of the parent rocks and the 0.25–0.50-mm fraction of each sand was done to monitor major mineralogic control, if any, on chemical compositions of the samples.

Our data show that the abundances of the Si and Al in sediments do not discriminate provenance. Abundances of Ca, Mg, Fe and Ti may broadly distinguish between sands derived from metamorphic and igneous source rocks, at least in the area studied. Differences in abundances of the Ba and Th, and the ratio of La/Lu between granitic, tonalitic and amphibolitic parent rocks are preserved in the daughter sediments that we studied. However, the size of the Eu anomaly in the REE patterns of different daughter sediments is not diagnostic of parent rocks. Abundances of Co and Sc distinguish between sediments derived from felsic and mafic rocks. A better provenance discrimination is obtained if the ratios La/Sc, Th/Sc, La/Co, Ba/Sc and Ba/Co are used.

Petrologic modal data show that mineral contents and chemical compositions of parent rocks are compatible with each other. The chemical composition of the sands may be roughly correlated to the petrological modal data but the abundances of some minor and trace elements of sediments cannot be inferred from modal mineralogy. This is expected because these elements may concentrate in accessory minerals and/or may weather out into aqueous or clay mineral fractions; it is also compatible with conclusions of previous studies that some of these elements do not reside in sand-size fractions of siliciclastic sediments.     

Atmospheric chemical composition of the halo star HD 221170 from a synthetic-spectrum analysis

The atmospheric abundances of 30 chemical elements in the halo star HD 221170 are analyzed by fitting synthetic spectra to observed spectra (i) with a resolution of 60 000 and signal-to-noise ratios of about 200 taken with the 1.93-m telescope of the Observatoire de Haute Provence and (ii) with a resolution of 35 000 and signal-to-noise ratios of more than 100 taken with the 2-m telescope of the Terskol Peak Observatory. The derived parameters of the stellar atmosphere are T_eff=4475 K, log g=1.0, [Fe/H]=?2.03, V_micro=1.7 km/s, and V_macro=4 km/s. The parameters T_eff, log g, [Fe/H], and V_micro can be determined by analyzing the variations of the rms error of the mean iron abundance derived using different model atmospheres. The chemical composition of the star’s atmosphere is analyzed. The abundances of a total of 35 elements in HD 221170 have been derived in this paper and in previous studies. Overall, the abundances of elements lighter than praseodymium are consistent with the elemental abundances in the atmospheres of stars with similar metal deficits. Copper and manganese are underabundant by ?2.9 and ?2.6 dex, respectively, relative to the Sun (when the analysis includes the effects of hyperfine structure). Heavy r-process elements (starting from praseodymium) are overabundant compared to iron-group elements. This can be explained by an enrichment in r-process elements of the material from which the star was formed.     

Thallium and lead in the Allende C3V carbonaceous chondrite. A study of the matrix phase

Tl and Pb isotopic abundances have been measured in various phases from Allende and the distribution and siting of these elements in the matrix phase investigated. Matrix fractions, prepared by sieving, sedimentation, magnetic separation and acid etching, were further characterised by X-ray diffraction and SEM. Tl concentrations range from 1 ppb in coarse grained inclusions to 1560 ppb in the acid-etched carbon residues and from 32 ppb to 194 ppb in the 16 matrix fractions. Pb concentrations which range from 0.1 ppm to 3.1 ppm, are enhanced in magnetic phases and depleted in Allende pentlandite relative to the whole meteorite. The Tl-²⁰⁴Pb abundance diagram is described near the origin by the inclusions and chondrules and extends through sulphide to the non-magnetic and magnetic matrix fractions. Abundances in the finest grained matrix fractions form a linear trend which passes through the origin and the Orgueil and Murchison whole meteorite data. The deviation of magnetic matrix fractions from the above linear trend is probably related to the presence of an intimate association of an awaruite-sulphide-carbon species. 92% of the Tl in the carbon residues, which is released on hydrolysis with HCl, probably resides in an organic host molecule(s) on the macromolecular carbonaceous material, whereas the surface film of organics on the matrix grains shows no apparent enrichment of Tl.Tl and ²⁰⁴Pb abundances revealed an inverse correlation with grain size and a distribution within the grains rather than as a surface layer, is indicated. Constraints placed by the data on the formational environment of the matrix grains are considered. Interstellar shock heating and rapid radiative cooling is a possible mechanism for the establishment of the observed inverse correlation of volatile abundance with grain size. Matrix data do not lend support for a recent redistribution of lead as an explanation for the apparent excess Pb in Allende. The apparent initial Pb isotopic compositions of the matrix fractions are heterogeneous and not attributable to terrestrial contamination. The very magnetic fractions have high abundances of Pb and the least radiogenic apparent initial Pb compositions, whereas the non-magnetic fractions have lower Pb abundances but more radiogenic apparent initial Pb compositions. The data also indicate that use of the predicted Tl-²⁰⁴Pb cosmothermometer, to infer accretion temperatures, is apparently not valid for individual phases of Allende.     

Development of the early continental crust. Part III. Depletion of incompatible elements in the mantle

New analyses and critical re-evaluation of older data permit another estimate of the abundances of some 42 elements in the silicate shells of the Earth, excluding the core.These data and estimations of volcanic rock production lead to a series of estimates of the mass-fractions of depleted and undepleted mantle. Most likely estimates of the latter lie in the range 0.2–0.4. The best estimates are obtained for the most incompatible elements K, Rb, Sr, Ba, Nb, Th, U.The development of the continental crust and the change in tectonic processes over time is consistent with these interpretations.     

Are C1 chondrites chemically fractionated? a trace element study

Six C1 chondrite samples and a C2 xenolith from the Plainview H5 chondrite were analyzed by radiochemical neutron activation for the elements Ag, Au, Bi, Br, Cd, Ce, Cs, Eu, Ge, In, Ir, Lu, Nd, Ni, Os, Pd, Pt, Rb, Re, Sb, Se, Sn, Tb, Te, Tl, Yb, and Zn. The data were combined with 9 earlier analyses from this laboratory and examined for evidence of chemical fractionation in C1 chondrites.A number of elements (Br, Rb, Cs, Au, Re, Os, Ni, Pd, Sb, Bi, In, Te) show small but correlated variations. Those of the first 8 probably reflect hydrothermal alteration in the meteorite parent body, whereas those of Sb, Bi, In, and Te may at least in part involve nebular processes. Br and Au show systematic abundance differences from meteorite to meteorite, which suggests hydrothermal transport on a kilometer scale. The remaining elements vary from sample to sample, suggesting transport on a centimeter scale.There is no conclusive evidence for nebular fractionation affecting C1 's. Though C1 chondrites have lower $\text{Zr}\text{Hf}$ and $\text{Ir}\text{Re}$ ratios than do other chondrite classes, these ratios vary in other classes, suggesting that those classes rather than C1's are fractionated. Three fractionation-prone REE—Ce, Eu, and Yb have essentially the same relative abundances in C1's and all other chondrite classes, and hence apparently are not fractionated in C1's. We did not confirm the large Tb and Yb variations in C1's reported by other workers.We present revised mean C1 abundances for 35 elements, based on the new data and a critical selection of literature data. Changes are generally less than 10%, except for Br, Rb, Ag, Sb, Te, Au, and the REE.The Plainview C2 xenolith has normal trace element abundances, except for 3 elements falling appreciably above the C2 range: Rb, Cs, and Bi. Hydrothermal alteration may be the reason for all 3, though nebular fractionation remains a possibility for Bi.     

Data Analysis of Chang’E-1 Gamma-Ray Spectrometer and Global Distribution of U, K, and Th Elemental Abundances

Gamma-ray spectrometer (GRS) is one of the main payloads on the Chang’E-1 (CE-1) lunar probe, mainly aimed to detect the elemental abundances and distributions on the lunar surface. At 03:58 on 28 November 2007, it performed the first observation of the lunar gamma rays. As of 24 October 2008, 2105?h of effective gamma rays spectra had been acquired by CE-1 GRS, which covers the whole surface of the moon. This paper mainly describes the data processing procedures and methods of deriving the elemental abundances by using the CE-1 GRS time series corrected spectra: first, to bin data into pixels for mapping; then, to perform a background deduction of the cumulative spectra and obtain a peak area of the elements; and finally, to use the elemental abundances inversion model to produce the elemental abundances. Based on these processing methods, the global abundance maps of U, K, and Th at a 5°×5° equal-area pixel are acquired by CE-1 GRS data. The paper gives a preliminary analysis of the uncertainties of the elemental abundances     

Core-Mantle equilibrium: Comments on a paper by R. Brett

Brett's arguments in the preceding paper are critically reviewed. It is concluded that the abundances of Ni, Co, Cu, Au and Pt in the upper mantle, the oxidation state of this region and the nature of the volatiles inferred to have been degassed from the upper mantle are not readily explained if the earth has accreted from a well mixed reservoir of preexisting metal and silicate particles in the solar nebula which were equilibrated within the earth prior to separation of the core. The data can be readily explained if it is assumed that the earth accreted inhomogeneously in a state which was initially out of overall chemical equilibrium and that equilibrium, although approached, was not finally achieved during core-segregation.     

The geochemistry of the volatile trace elements As, Cd, Ga, In and Sn in the Earth’s mantle: New evidence from in situ analyses of mantle xenoliths

The abundances of 30 trace elements, including the volatile chalcophile/siderophile elements As, Cd, Ga, In and Sn were determined by laser ablation ICP-MS in minerals of 19 anhydrous and 5 hydrous spinel peridotite xenoliths from three continents. The majority of samples were fertile lherzolites with more than 5% clinopyroxene; several samples have major element compositions close to estimates of the primitive mantle. All samples have been previously analysed for bulk-rock major, minor and lithophile trace elements. They cover a wide range of equilibration temperatures from about 850 to 1250 °C and a pressure range from 0.8 to 3.0 GPa. A comparison of results from bulk-rock analyses with concentrations obtained from combining silicate and oxide mineral data with modal mineralogy, gave excellent agreement, with the exception of As. Arsenic is the only element analysed that has high concentrations in sulphides. For all other elements sulphides can be neglected as host phases in these mantle rocks. The major host phase for Cd, In and Sn is clinopyroxene and if present, amphibole. Cadmium and In appear to behave moderately incompatibly during mantle melting similar to Yb.The data yield new and more reliable mantle abundances for Cd (35 ± 7 ppb), In (18 ± 3 ppb) and Sn (91 ± 28 ppb). The In value is similar to the Mg and CI-normalized Zn abundance of the mantle, although In is cosmochemically more volatile than Zn. The high In content suggests a high content of volatile elements in general in proto-Earth material. The lower relative abundances of volatile chalcophile elements such as Cd, S, Se and Te might be explained by sulphide segregation during core formation. The very low relative abundances of volatile and highly incompatible lithophile elements such as Br, Cl and I, and also C, N and rare gases, imply loss during Earth accretion, arguably by collisional erosion from differentiated planetesimals and protoplanets.     

月球岩浆洋演化的实验岩石学研究进展SCIEI北大核心CSCD

由于缺少直接来自月球深部的岩石样品,实验和计算模拟是认识早期月球演化过程的有效方法和手段。20世纪70年代以来,陆续开展了大量的实验岩石学和实验地球化学工作对月球岩浆洋(lunar magma ocean,LMO)演化模型进行验证和修正。但是,学界对LMO模型中的两个关键性参数,即初始物质组成和熔融深度,仍然存在不同的认识。根据月震和重力探测数据推测的平均月壳厚度的差异、月球样品含水量的研究以及新的遥感数据解译发现月表广泛分布富镁铝尖晶石(Cr#<5)等等,直接影响我们对月球初始物质组成和LMO深度以及月球深部高压矿物相的评估。本文通过整理高温高压实验岩石学和实验地球化学在研究LMO演化方面的一系列研究成果,主要聚焦以下几个科学问题:(1)月球初始物质组成中的难熔元素和挥发分含量,以及LMO深度对月壳厚度、结晶矿物的种类及含量有着决定性的影响;(2)高压矿物相石榴子石在月球深部稳定存在的可能性及其对残余岩浆中微量元素的分配行为的制约;(3)特殊类型的月球样品(包括火山玻璃、镁质岩套等)的成因机制对月球深部物质组成具有指示意义;(4)月核的不同物质组成对LMO模型的初始成分含量,特别是微量元素的限定作用。我们以最新的观测数据和月球样品的分析结果为依据,对已有的LMO演化模型进行重新评估,提出月球深部含有石榴子石的LMO演化模型的可能性,并对该方向亟需开展的工作进行探讨。     

Harold N. Fisk: a luminescent man

The publication of the “Geological Investigation of the Alluvial Valley of the Lower Mississippi River” (Fisk, 1944) was the greatest achievement of Harold N. Fisk's remarkable career. Its creative rigor and vision marked a great leap forward in understanding the alluvial and sedimentological processes of the Mississippi Valley and the fundamental value of these insights to river engineering strategies and techniques. Fisk's monumental effort shares many common elements with great strides in other disciplines made during this era. The period from the 1920s to the 1940s was marked by breakthroughs in fields such as hydraulics, medicine, chemistry, and small-particle physics that featured grand vistas of discovery. Fisk's triumph, as in other cases, can be attributed to factors that supplemented and complemented his personal scientific brilliance. He displayed less tangible elements of personality, shrewdness, and leadership that enabled him to attract interest and support for his undertakings, build a highly devoted team of associates, maintain the confidence of sponsors, and “market” his discoveries through clever media relations. This remarkable and in some respects enigmatic man was able to make the most of his opportunities in much the same way as his stellar contemporaries. Doggedness, vision, insight, personal qualities, and the availability of Federal needs and generous funding were all synergetic, crucial elements in the preparation and acceptance of the “Fisk Report.”     

Trace element concentrations in silicate spherules from oceanic sediments

The possible existence of meteoritic spherules was investigated among several silicate spherules separated from oceanic sediments and analyzed by means of INAA (instrumental neutron activation analysis).A 0.72 mg glassy spherule was found to have uniform enrichment of 4 ~ 5 for the refractory REE (rare earth elements) and Sc with substantial depletion of Ce relative to chondritic abundances. This implies that this spherule is meteoritic in origin and that the enrichment of refractory elements was established by high temperature heating in a high O/H environment, possibly at the time of entering the Earth's atmosphere.The other three analyzed spherules showed major and trace element abundances that are consistent with an origin in the oceanic environment.     

Major and trace element variation in ilmenite in the Skaergaard Intrusion: petrologic implications

Ilmenite separates from the floor (LS), roof (UBS), and wall (MBS) sequences of the Skaergaard Intrusion were analyzed for major and trace elements using DCP-AES and ICP-MS techniques. In all three sequences, FeO progressively increases, and MgO and Al₂O₃ progressively decrease with differentiation. Although trace element abundances are, in general, higher in UBS ilmenite than in MBS and LS ilmenite, all three sequences have similar trends for trace element abundance vs. crystallization. Ba, Cs, Rb, Sr, Th, U, Y, and the REEs are excluded elements in ilmenite, and remained at low abundances during differentiation. Cr, Ni, Sc, and V are included elements in ilmenite and other mafic phases, and decreased during differentiation. V contents in ilmenite, however, do not decrease significantly until the upper part of the middle zone, suggesting that magnetite did not begin to affect the magma differentiation trend until much later than when it first appears in the intrusion. Hf, Nb, Ta, and Zr, which are strongly excluded elements in silicates, are included elements in ilmenite. The element ratios Zr/Hf, Y/Ho, Nb/Ta, and U/Th are relatively constant in Skaergaard ilmenite from different parts of the intrusion, suggesting that fluid transport did not significantly effect these elements during differentiation or post-solidification cooling. Calculated partition coefficients for ilmenite in the Skaergaard Intrusion are similar to those reported from previous studies of lunar and terrestrial basalts and kimberlites, and for most elements are significantly lower than those reported for ilmenite in rhyolitic magma. Similar D_i's for Zr, Hf, Nb, and Ta suggest that ilmenite crystallization did not significantly affect Zr/Nb or Hf/Ta in the Skaergaard magma, but the ratios of Zr, Hf, Nb, or Ta to other high field strength elements, such as Th, U, Y, or the REEs, may have been altered by ilmenite fractionation.     

Geochemistry of cumulus peridotites and gabbros from the Marum ophiolite complex,northern Papua New Guinea

The layered cumulus rocks of the Marum ophiolite complex in northern Papua New Guinea range from highly magnesian dunite, wehrlite, and lherzolite through pyroxenite to norite-gabbro with minor anorthosite and ferronorite-gabbro near the top of the sequence. Most of the cumulates, particularly the gabbroic rocks, are characterised by recrystallised adcumulus textures and all intercumulus melt (mesostasis) has been expelled. Trends in the cumulate sequence from Mg-rich to more Fe-, Ca- and Al-rich compositions are consistent with the formation of the layered sequence by magmatic accumulation from mafic tholeiitic magmas with varying degrees of differentiation. The cumulates are characterised by extremely low levels of ‘incompatible’ elements (K, Ba, Rb, P, Zr, Nb, Hf, Y and REE) at all levels of differentiation. REE patterns are strongly depleted in LREE; HREE abundances range from ≦0.3 chondrites in peridotite to 3 x chondrites in the norite-gabbros. The Marum cumulates resemble low-Ti peridotites and gabbros found in other orthopyroxene-bearing ophiolite sequences. The parent magmas of the Marum cumulates are inferred to have been strongly depleted in ‘incompatible’ trace elements (～ 2,000 ppm Ti, ～20 ppm Zr, 6–9 x chondrites HREE with La_N/Sm_N～0.5). These abundances are lower than found in typical MORB and back-arc basin basalts or their picritic parents. The dissimilarity of trace element abundances of the inferred Marum parent magmas with MORB-type high-alumina olivine tholeiites supports the conclusion drawn previously from the petrology of the cumulates that the parent magmas to the Marum ophiolite were not of MORB composition but resembled the strongly depleted, Ni-rich magnesian olivine-poor tholeiites and quartz tholeiites of the Upper Pillow Lavas of the Troodos ophiolite. The Marum parent magmas are believed to have been formed by shallow melting of refractory peridotite, and are chemically and genetically distinct from the LREE-enriched high-Ti lavas (Tumu River basalts) which occur in faulted contact. The geochemical data do not permit unequivocal assignment of a tectonic environment for the formation of either the Tumu River basalts or the plutonic suite; their juxtaposition results from thrust emplacement.     

Solar-system abundances of the elements

A new abundance table has been compiled, based on a critical review of all C1 chondrite analyses up to mid-1982. Where C1 data were inaccurate or lacking, data for other meteorite classes were used, but with allowance for fractionation among classes. In a number of cases, interelement ratios from meteorites or lunar and terrestrial rocks as well as solar wind were used to check and constrain abundances. A few elements were interpolated (Ar, Kr, Xe, Hg) or estimated from astronomical data (H, C, N, O, He, Ne).For most elements, the new abundances differ by less than 20% from those of Cameron (1982a). In 14 cases, the change is between 20 and 50% (He, Ne, Be, Br, Nb, Te, I, Xe, La, Gd, Tb, Yb, Ta and Pb) and in 5 others, it exceeds 50% (B, P, Mo, W, Hg). Some important interelement ratios ($\text{Na}\text{K}$, $\text{Se}\text{Te}$, $\text{Rb}\text{Sr}$, $\text{Kr}\text{Xe}$, $\text{La}\text{W}$, $\text{Th}\text{U}$, $\text{Pb}\text{U}$, etc.) are significantly affected by these changes.Three tests were carried out, to see how closely C1 chondrites approximate primordial solar system abundances. (1) A plot of solar vs Cl abundances shows only 7 discrepancies by more than twice the nominal error of the solar abundance: Ga, Ge, Nb, Ag, Lu, W and Os. Most or all apparently reflect errors in the solar data or f-values. (2) The major cosmochemical groups (refractories, siderophiles, volatiles, etc.) show no significant fractionation between the Sun and C1's, except possibly for a slight enrichment of volatiles in Cl's. (3) Abundances of odd-A nuclides between A = 65 and 209 show an almost perfectly smooth trend, with elemental abundances conforming to the slope defined by isotopic abundances. There is no evidence for systematic fractionation of the major cosmochemical groups from each other. Small irregularities (10–15%) show up in the Ag-Cd-In and Sm-Eu regions; the former may be due to a ~ 15% error in the Ag abundance and the latter, to a 10–20% fractionation of Eu during condensation, to contamination of C1 chondrites with interplanetary dust during regolith exposure, or to a change from s-process to r-process dominance.It appears that the new set of abundances is accurate to at least 10%, as irregularities of 5–10% are readily detectable. Accordingly, Cl chondrites seem to match primordial solar-system matter to ? 10%, with only four exceptions. Br and I are definitely and B is possibly fractionated by hydrothermal alteration, whereas Eu seems to be enriched by nebular condensation or regolith contamination.