The abundances of titanium,zirconium and hafnium in stony meteorites     

Masako Shima 《Geochimica et cosmochimica acta》1979,43(3):353-362

The concentrations of Ti, Zr and Hf have been determined, by a stable isotope dilution method, in 27 chondrites, seven achondrites and standard rock samples BCR-1 and W-1.Among all chondrites investigated, enstatite chondrite Abee is lowest in Ti atomic ratio compared with Si while all carbonaceous chondrites show higher values. The Zr contents are higher in CII and CIII chondrites, relative to the other groups of chondrites. There is a clustering of Ti and Zr within each group. The $\text{Zr}\text{Hf}$ ratios in CII, CIII. E and H chondrites are essentially the same, while that in the CI chondrite is lower and in L, LL and unequilibrated chondrites are higher.The concentrations of Ti, Zr, Hf and $\text{Ti}\text{Zr}$, $\text{Zr}\text{Hf}$ ratios in achondrites are variable, even among members of the same group.Based on these results, condensation models for these elements are discussed. The variable results for Ti, Zr and Hf in achondrites may be due to the reheating recrystallization and metamorphic processes.‘Cosmic atomic abundances’ of Ti, Zr and Hf are calculated as 2470, 11.2 and 0.185. respectively for Si = 10⁶ atoms.  相似文献   

Trace and major elements in the sea-surface microlayer     

N.J. Pattenden  R.S. Cambray  K. Playford 《Geochimica et cosmochimica acta》1981,45(1):93-100

Sea-surface microlayer samples were obtained in the North sea, by collecting droplets ejected by bubbles bursting at the sea-surface. The samples were analysed for some trace and major elements, mainly by neutron activation and atomic absorption spectrophotometry, and the results were compared with those from samples of bulk seawater taken at the same time. For any element X, the results may be expressed as a concentration factor related to Na, thus: $\text{CF =}\text{ratio of X and Na concentrations in microlayer sample}\text{similar ratio in corresponding bulk seawater sample}$The CF values for trace elements showed wide fluctuations from sample to sample. The only two elements for which relatively unambiguous CF values were obtained were Sc (from 2.5 to 100) and Pb (from 140 to 410). Other CF values were obtained for Co (up to 76). Zn (<50), La (up to 3000) and Ce (up to 500). The major ions Mg, Cl, K, Ca, Br, gave CF values between 0.54 and 2.2 in all cases measured. It is concluded that large enrichments of some trace elements can occur in the surface microlayer, but enrichment of major ions has not been observed.Concentrations of about 30 trace elements in particulate form in bulk seawater were measured in the course of the study.  相似文献   

$\text{Ca}\text{Al}$ ratio and composition of the Earth's upper mantle     

H Palme  K.G Nickel 《Geochimica et cosmochimica acta》1985,49(10):2123-2132

Undifferentiated meteorites (chondrites) have the same relative abundances of refractory lithophile elements (Ca, Al, Ti, Sc, REE, etc.), despite variable absolute concentrations. The reasonable assumption of chondritic ratios among refractory elements in the bulk Earth is used to constrain the chemical composition of the upper mantle in the following way: Correlations of the compatible refractory elements Ca, Al, Ti, Sc and Yb with MgO are worldwide very similar in suites of spinel-lherzolite xenoliths from basaltic rocks. Such suites represent upper mantle material depleted to differing degrees by extraction of partial melts. From these refractory elements vs. MgO correlations, ratios of pairs of refractory elements were calculated at various MgO contents. Chondritic $\text{Al}\text{Ti}$ and $\text{Sc}\text{Ti}$ ratios were only obtained for MgO contents below 36%. A chrondritic $\text{Sc}\text{Yb}$ ratio requires an MgO content above 35%. We therefore accept 35.5% as the most reasonable MgO content of undepleted upper mantle. This MgO content is slightly below the spinel-lherzolite with the lowest measured MgO content (36.22%). The corresponding Al₂O₃ content of 4.75% is higher than in previous estimates of upper mantle composition. The concentrations of other elements were obtained from similar correlations at a MgO content of 35.5%. The resulting present upper mantle composition is enriched in refractory elements by a factor of 1.49 relative to Si and Cl and by a factor of 1.12 for Mg relative to Si and Cl. These enrichments are in the same range as those for the Vigarano type carbonaceous chondrites. The Mg/Mg + Fe ratio of 89 is slightly lower than previous estimates.The $\text{Ca}\text{Al}$ ratio in spinel lherzolite suites is, however, uniformly higher worldwide than the chondritic ratio by about 15%. Orogenic peridotites as well as komatiites appear to have similar non-chondritic $\text{Ca}\text{Al}$ ratios. It is therefore suggested that this non-chondritic $\text{Ca}\text{Al}$ ratio is a characteristic of the upper mantle, possibly since the Archean. A minor fractionation of about 4% of garnet in an early, global melting event (deep magma ocean?) is presented as the most likely cause for the high $\text{Ca}\text{Al}\text{-}\text{ratio}$. In this case the addition of 4% of such a garnet component to the undepleted present upper mantle would be required to obtain the composition of the primordial upper mantle. The $\text{Ca}\text{Al}\text{-}\text{ratio}$ of this primordial mantle would be 15% higher than that of the undepleted present upper mantle, resulting in an enrichment of refractory elements of 1.70 ($\text{Al}\text{Si}$ relative to Cl) for the primordial upper mantle.  相似文献   

Evaluation of fractionation effects during the early stages of primary migration     

Cs. Sajgo  J.R. Maxwell  A.S. Mackenzie 《Organic Geochemistry》1983,5(2):65-73

A stepwise extraction technique, based on that of Beletskaya (1972), has been aplied to sedimentary rock samples of variable grain size and maturity from a Neogene sequence in the Pannonian Basin (S.E. Hungary). The resulting chloroform extracts, claimed by Beletskaya (1978) to sample “open” and mineralogically “closed” pores, have been analysed by gas chromatography and gas chromatography-mass spectrometry. Differences in the concentrations of the two extracts and the concentrations of their hydrocarbon fractions, and in the distributions of $\text{n}$-alkanes and steroid hydrocarbons suggest that either the “open” pores are impregnated with mature oil which has migrated from depth, or that movement of organic material from the “closed” to “open” pores occurs with considerable fractionation based on both polarity and molecular size. The implications of these differences for source rock-oil correlation studies are discussed and an assessment of mechanisms for primary migration is given.  相似文献   

Arsenic and antimony in geothermal waters of Yellowstone National Park,Wyoming, USA     

Robert E. Stauffer  John M. Thompson 《Geochimica et cosmochimica acta》1984,48(12):2547-2561

A total of 268 thermal spring samples were analyzed for total soluble As using reduced molybdenum-blue; 27 of these samples were also analyzed for total Sb using flame atomic absorption spectrometry. At Yellowstone the $\text{Cl}\text{As}$ atomic ratio is nearly constant among neutral-alkaline springs with Cl > 100 mg L^?1, and within restricted geographic areas, indicating no differential effects of adiabatic vs. conductive cooling on arsenic. The $\text{Cl}\text{As}$ ratio increases with silica and decreases with decreasing $\text{Cl}\text{ΣCO}{}_3$; the latter relationship is best exemplified for springs along the extensively sampled SE-NW trend within the Lone Star-Upper-Midway Basin region. The relationship between $\text{Cl}\text{As}$ and $\text{Cl}\text{ΣCO}{}_3$ at Yellowstone suggests a possible rock leaching rather than magmatic origin for much of the Park's total As flux. Condensed vapor springs are low in both As and Cl. Very high $\text{Cl}\text{As}$ ratios ( > 1000) are associated exclusively with highly diluted (Cl < 100 mg L^?1) mixed springs in the Norris and Shoshone Basins and in the Upper White Creek and Firehole Lake areas of Lower Basin. The high ratios are associated with acidity and/or oxygen and iron; they indicate precipitation of As following massive dilution of the Asbearing high-Cl parent water.Yellowstone Sb ranged from 0.009 at Mammoth to 0.166 mg L^?1 at Joseph's Coat Spring. Within basins, the $\text{Cl}\text{Sb}$ ratio increases as the $\text{Cl}\text{ΣCO}{}_3$ ratio decreases, in marked contrast to As. Mixed springs also have elevated $\text{Cl}\text{Sb}$ ratios. White (1967) and Weissberg (1969) previously reported stibnite (Sb₂S₃), but not orpiment (As₂S₃), precipitating in the near surface zone of alkaline geothermal systems.  相似文献   

The major-element chemistry of suspended matter in the Amazon Estuary     

E.R. Sholkovitz  N.B. Price 《Geochimica et cosmochimica acta》1980,44(2):163-171

Suspended matter from the surface waters of the Amazon Estuary were collected during May and June 1976 on the ‘R/V Alpha Helix’, and their major-element compositions (Al, Si, Ti, K, Mg, Ca, P, Fe and Mn) were measured.Between salinities of 0 and 10%. the suspended material, predominantly terrigenous in derivation, decreases in load from 500 to 3 mg/l, but has a chemical composition which remains essentially constant. With the onset of a large amount of biological productivity at approximately 10%. salinity, there are large increases in the ratios of $\text{Si}\text{Al}$, $\text{P}\text{Al}$, $\text{Ca}\text{Al}$, $\text{Mg}\text{Al}$, $\text{Ti}\text{Al}$ and $\text{Mn}\text{Al}$ which are maintained at higher salinities. Calculations of “excess” concentrations of elements held in the non-terrigenous components of the suspended material further support our main conclusion that Si, P, Ca, Mg, Ti and Mn are incorporated into the skeletal and organic phases of marine phytoplankton (predominately diatoms) of the Amazon Estuary. The data suggest, but with less certainty, that Fe and K follow the above elements.This study has demonstrated that the chemical composition of river-introduced suspended matter can be significantly altered by biological activity within estuarine waters as can be the geochemical cycle of inorganic elements.  相似文献   

$\text{Sr}\text{Ca}$ and $\text{Mg}\text{Ca}$ ratios in polygenetic carbonate allochems from a Michigan marl lake     

Thomas N Treese  Robert M Owen  Bruce H Wilkinson 《Geochimica et cosmochimica acta》1981,45(3):439-445

Rapid accumulation of CaCO₃ is occurring in Littlefield Lake, a marl lake located in central Michigan. The sediment, which is 95% CaCO₃, primarily consists of eight different genetic groups of carbonate allochems. These include calcite muds, sands, algal oncoids and Chara encrustations, as well as the dominant aragonitic gastropods Valvota tricarinota. Gyraulus deflectus and Amnicola integra. and the dominant aragonitic pelecypod Sphaerium partumeium. Samples of each of these groups were analyzed for Ca, Sr and Mg. Molar $\text{Mg}\text{Ca}$ ratios are primarily controlled by allochem mineralogy, with calcitic forms having $\text{Mg}\text{Ca}$ ratios 5–10 times larger than aragonitic (shelled) forms. The $\text{Sr}\text{Ca}$ ratios are primarily controlled by biochemical fractionation, and are significantly lower than $\text{Sr}\text{Ca}$ ratios of inorganically precipitated aragonite from other settings. Partition coefficients were determined for both Sr and Mg for each carbonate allochem group and, based on comparisons with results reported by other workers, the partition coefficients determined here are generally considered ‘typical’ or representative values for biogeneous freshwater carbonates. An analysis of variance of the data indicates that most genera and species of carbonate-secreting organisms in marl lakes have highly characteristic $\text{Sr}\text{Ca}$ and $\text{Mg}\text{Ca}$ ratios. These ratios can potentially serve as geochemical tracers in future investigations of lacustrine carbonate diagenesis. Both Sr and Mg are influenced by grain size and/or surface area, probably due to the presence of these elements in non-lattice-held (exchangeable) positions.  相似文献   

Uranium and thorium microdistributions in stony meteorites     

Ghislaine Crozaz 《Geochimica et cosmochimica acta》1979,43(1):127-136

Uranium distributions have been determined in seventeen meteorites using fission track techniques. In seven cases, Th was also determined by a new method using fast neutrons. The actinides are generally concentrated in phosphates, usually whitlockite and/or chlorapatite. Wherever whitlockite and chlorapatite coexist, chlorapatite is richer in uranium. U concentrations in a given phosphate phase are highly variable from meteorite to meteorite and sometimes also show large variations in the same meteorite. A clinopyroxene phase enriched in U (0.2–0.3 ppm) is usually found in Ca-rich achondrites. The $\text{Th}\text{U}$ ratios of phosphates differ considerably from whole rock values indicating that these elements were fractionated during the meteorite formation.  相似文献   

Al-Sm-Eu-Sr systematics of eucrites and Moon rocks: Implications for planetary bulk compositions     

Paul H Warren 《Geochimica et cosmochimica acta》1983,47(9):1559-1571

Analysis of the Eu and Sr “anomalies” of eucrites and lunar rocks allows constraints to be placed on the bulk compositions of the eucrite parent body (EPB) and the Moon. The elements Al, REE, and Sr, all are essentially incompatible with the major minerals of these small, low-?(O₂) bodies, except for plagioclase, into which Al, Sr, and Eu tend to concentrate. Therefore, the hypothesis that Al, REE, and Sr in the EPB and the Moon are all in proportions close to those in the bulk solar system (i.e., chondrites) leads to certain predictions about the concentrations of these elements in samples affected by plagioclase fractionation. The predictions are almost ideally fulfilled by eucrites and lunar samples. For the EPB, the ratios $\text{REE}\text{Al}$, $\text{Sr}\text{Al}$, and $\text{Sr}\text{REE}$ are constrained to be probably within 10%, almost certainly within 20%, of the chondritic ratios. For the more complicated Moon, the constraints are less precise: $\text{REE}\text{Al}$ is very probably within 25% of chondritic; $\text{Sr}\text{Al}$ and $\text{Sr}\text{REE}$ are probably within 35% of chondritic. These findings are proof that there is a strong similarity between the bulk compositions of the planets and the compositions of chondritic meteorites.The eucrites' Sm-Eu-Sr systematics are also valuable sources of constraints on the distribution coefficients for Eu and Sr into plagioclase, at low ?(O₂). From the slope of data for noncumulate eucrites on a Eu-Sm plot, D(Eu,pl/liq) can be inferred to be 1.1_?0.1^0.2. From the slope on a Sr-Sm plot, D(Sr,pl/liq)) can be inferred to be 1.5 ± 0.3. In the case of D(Eu), this is in excellent agreement with experimental data. In the case of D(Sr), the empirical result is probably more appropriate for eucritic systems than most experimental data, which, due to compositional effects, scatter widely.  相似文献   

Chemical classification of iron meteorites—IX. A new group (IIF), revision of IAB and IIICD,and data on 57 additional irons     

Alfred Kracher  John Willis  John T Wasson 《Geochimica et cosmochimica acta》1980,44(6):773-787

Structural observations and concentrations of Ni, Ga, Ge and Ir allow the classification of 57 iron meteorites in addition to those described in the previous papers in this series; the number of classified independent iron meteorites is now 535. INAA for an additional six elements indicates that five previously studied irons having very high $\text{Ge}\text{Ga}$ ratios are compositionally closely related and can be gathered together as group IIF. A previously unstudied iron, Dehesa, has the highest $\text{Ge}\text{Ga}$ ratio known in an iron meteorite, a ratio 18 × higher than that in CI chondrites. Although such high $\text{Ge}\text{Ga}$ ratios are found in the metal grains of oxidized unequilibrated chondrites, their preservation during core formation requires disequilibrium melting or significant compositional and temperature effects on metal/silicate distribution constants and/or activity coefficients. In terms of $\text{Ge}\text{Ga}$ ratios and various other properties group IIF shows genetic links to the Eagle Station pallasites and $\text{CO}\text{CV}$ chondrites. Klamath Falls is a new high-Ni, low-Ir member of group IIIF that extends the concentration ranges in this group and makes these comparable to the ranges in large igneous groups such as IIIAB. Groups IAB and IIICD have been revised to extend the lower Ni boundary of group IIICD down to 62 mg/g. The iron having by far the highest known Ni concentration (585 mg/g), Oktibbeha County, is a member of group IAB and extends the concentration ranges of all elements in this nonmagmatic group. Morasko, a IAB iron associated with a crater field in Poland, is paired with the Seeläsgen iron discovered 100 km away. All explosion craters from which meteorites have been recovered were produced by IAB and IIIAB irons.  相似文献   

Ammonia-ammonium leaching of deep-sea manganese nodules     

K.N Han  M Hoover  D.W Fuerstenau 《International Journal of Mineral Processing》1974,1(3):215-230

Ammonia-ammonium leaching of samples of nodules from several different locations was carried out after reduction of the nodules under $\text{CO}\text{CO}{}_2$ gas mixtures at 400, 600, and 800°C. In accordance with thermodynamic analysis, nickel, copper and cobalt oxides in the nodules are preferentially reduced with a $\text{60}\text{40}$ gas mixture of $\text{CO}\text{CO}{}_2$. After an initial reduction step with $\text{CO}\text{CO}{}_2$ at 600°C, leaching at room temperature and atmospheric pressure with aqueous ammonia-ammonium carbonate and ammonia-ammonium sulfate solutions yielded high extractions of copper and nickel (> 80%), and close to 50% for cobalt. The nature of the pores in nodules from different locations appears to affect the extraction process. A lower reduction temperature is required to obtain the same extraction of nickel, copper and cobalt in a sulfate system than is necessary in a carbonate system. However, a higher manganese content results in the sulfate leaching solutions as compared to the carbonate system, where essentially none of the manganese and iron are extracted.  相似文献   

Matrix corrections in trace-element analysis by X-ray fluorescence: An extension of the Compton scattering technique to long wavelengths     

R.W. Nesbitt  H. Mastins  G.W. Stolz  D.R. Bruce 《Chemical Geology》1976,18(3):203-213

Mass absorption coefficients (A₂) for a series of standard rocks, have been calculated in the wavelength region 0.492–3.03 $\text{a}\text{?}$. Plots of these data against the intensity of the Compton scattered peak [(I) Compton] give an excellent correlation for the wavelengths 0.429 $\text{a}\text{?}$ to the Fe-absorption edge (1.74 $\text{a}\text{?}$); the data confirm the observations of Reynolds. Hence, routine measurement of one peak will give the mass absorption coefficient of a sample in an analytically important region (Sn/1bK_α to Ni/1bK_α). A₂ has also been directly measured on three of the samples and systematic differences between calculated and measured are attributed to the measuring technique. At wavelengths longer than the Fe-absorption edge, (up to 3.03 $\text{a}\text{?}$) A₂ can be estimated using a combination of (I) Compton and Fe/1bK_α c.p.s. This technique enables meaningful matrix corrections to be carried out on the elements Co, Mn, Cr, V, Ti, Sc (K spectra) and Ba (L spectra). Cr and Ba results are presented for some standard rocks.  相似文献   

The distribution of trace elements in carbonaceous chondrites     

Hans-Josef Knab 《Geochimica et cosmochimica acta》1981,45(9):1563-1572

12 carbonaceous chondrites, amongst them representatives of nearly all known petrologic types were analyzed for twenty trace elements by spark source mass spectrography combined with the isotope dilution method. Data on different element groups (refractory, moderately volatile and volatile) show that the distribution of the trace elements in the carbonaceous chondrites, with the exception of Renazzo, can be well explained by Anders' two-component model. This is also valid for the highly metamorphosed CV5 chondrite Karoonda.Furthermore, it is observed that the $\text{Zr}\text{Hf}$-ratios in the carbonaceous chondrites increase with increasing petrologic type which is interpreted as the result of mixing two components with different $\text{Zr}\text{Hf}$-ratios  相似文献   

The rare alkalies in hydrothermal alteration at Wairakei and Broadlands,geothermal fields,N.Z.     

Reiner Goguel 《Geochimica et cosmochimica acta》1983,47(3):429-437

Drillcores and waters from Wairakei and Broadlands geothermal areas New Zealand have been analyzed for Li, Rb, Cs, Na, K, Mg, Ca, Al, Ti, Mn, and Be. The drillcores were altered to various degrees at temperatures below 300°C in slightly alkaline chloride water, probably derived from rock-water interaction in untapped horizons at higher temperature. It changes its composition as it leaches Ca and Na from the rock and adds K, Rb, Cs and Li. Evaluation of these changes in relation to the dimensions of the altered zone under observation suggests that a high mass ratio of water to rock (e.g., 100) and a period of up to 1 million years are responsible for the present stage of alteration.Increase of K and Rb in the altered rocks is a result of the formation of abundant adularia in addition to illite. The $\text{K}\text{Rb}$ ratio of the rock decreases during alteration but remains higher than that of the fluid. Only clay materials and zeolites that preferentially absorb Rb give slightly lower $\text{K}\text{Rb}$ ratios than the fluid.The mineral phases responsible for the uptake of lithium during alteration are chlorite (300 ppm Li) and quartz (up to 430 ppm Li). Li uptake in quartz is considered to be the mechanism by which Al-rich quartz crystallises from alumino-silicates. $\text{Li}\text{Al}$ atomic ratios of 0.3–0.57 and Al concentrations up to 3000 ppm have been observed.Relatively small concentrations of Cs are found in potassic minerals (e.g. 10 ppm Cs in adularia, 44 ppm Cs in illite). However, 240 ppm Cs are found in wairakite from Wairakei equilibrated at 235°C. Lower equilibration temperatures may lead to higher cesium concentrations. This effect, in conjunction with a more concentrated hydrothermal fluid, could explain a content of 4500 ppm Cs in wairakite extracted from a drillcore taken in the El-Tatio geothermal field in Chile.  相似文献   

A statistical model of proton binding by humus     

E.M. Perdue  J.H. Reuter  R.S. Parrish 《Geochimica et cosmochimica acta》1984,48(6):1257-1263

A model that considers both the carboxyl and weakly acidic groups of humus as continuous binding site distributions in which individual ligand concentrations are normally distributed with respect to the log $\text{K}$ values for proton binding is proposed. The concentration, mean log $\text{K}$ value, and variance for the log $\text{K}$ distribution of each class of functional groups are estimated by nonlinear regression analysis of titration data. The values obtained for those parameters are chemically reasonable and the extent of proton binding between pH 4.0 and pH 10.8 is accurately described by the model.  相似文献   

Are C1 chondrites chemically fractionated? a trace element study     

Mitsuru Ebihara  Rainer Wolf  Edward Anders 《Geochimica et cosmochimica acta》1982,46(10):1849-1861

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.  相似文献   

An empirical NaKCa geothermometer for natural waters     

R.O. Fournier  A.H. Truesdell 《Geochimica et cosmochimica acta》1973,37(5):1255-1275

An empirical method of estimating the last temperature of water-rock interaction has been devised. It is based upon molar Na, K and Ca concentrations in natural waters from temperature environments ranging from 4 to 340°C. The data for most geothermal waters cluster near a straight line when plotted as the function $\text{log (}\text{Na}\text{K}\text{) + β log [ √}\text{(Ca)}\text{Na}\text{]}$ vs reciprocal of absolute temperature, where β is either $\text{1}\text{3}$ or $\text{4}\text{3}$ depending upon whether the water equilibrated above or below 100°C. For most waters tested, the method gives better results than the $\text{Na}\text{K}$ methods suggested by other workers. The ratio $\text{Na}\text{K}$ should not be used to estimate temperature if $\text{√ (}\text{M}{}_{\mathrm{Ca}}\text{)}\text{M}{}_{\mathrm{Na}}$ is greater than 1. The $\text{Na}\text{K}$ values of such waters generally yield calculated temperatures much higher than the actual temperature at which water interacted with the rock.A comparison of the composition of boiling hot-spring water with that obtained from a nearby well (170°C) in Yellowstone Park shows that continued water-rock reactions may occur during ascent of water even though that ascent is so rapid that little or no heat is lost to the country rock, i.e. the water cools adiabatically. As a result of such continued reaction, waters which dissolve additional Ca as they ascend from the aquifer to the surface will yield estimated aquifer temperatures that are too low. On the other hand, waters initially having enough Ca to deposit calcium carbonate during ascent may yield estimated aquifer temperatures that are too high if aqueous Na and K are prevented from further reaction with country rock owing to armoring by calcite or silica minerals.The Na-K-Ca geothermometer is of particular interest to those prospecting for geothermal energy. The method also may be of use in interpreting compositions of fluid inclusions.  相似文献   

The partitioning of copper and molybdenum between silicate melts and aqueous fluids   总被引：4，自引：0，他引：4  

Philip A Candela  Heinrich D Holland 《Geochimica et cosmochimica acta》1984,48(2):373-380

The partitioning of copper and molybdenum between silicate melts and aqueous fluids has been determined at 750°C, and 1.4 Kb. The experiments were conducted in a $\text{1}\text{2}$ inch ID, rapid quench, cold seal pressure vessel. The aqueous and glass phase run products were analyzed by atomic absorption spectrophotometry and ion microprobe, respectively. The vapor/melt partition coefficient for copper, $\text{D}{}^{\mathrm{<mtext>v</mtext><mtext>l</mtext>}}{}_{\mathrm{Cu}}$, defined as the ratio of the concentrations of copper in the vapor to copper in the melt was found to be $\text{D}{}^{\mathrm{<mtext>v</mtext><mtext>l</mtext>}}{}_{\mathrm{Cu}}\text{= (9.1 ± 2.5)m}{}^{\mathrm{v}}{}_{\mathrm{Cl}}$ at NNO up to at least 4.5 moles of chlorine per kg of solution. The partition coefficient for molybdenum is equal to 2.5 ± 1.6 at NNO and QFM; its value is independent of the fluorine concentration of the melt up to at least 1.7 wt. percent fluorine, and of the chlorine concentration up to at least 4.5 moles of chlorine per kg of solution. Copper is probably present in the univalent state in both the silicate melt and in the associated aqueous phase at NNO; the most important aqueous complex of copper is probably CuCl⁰. Molybdenum is probably present in the aqueous phase as one or more molybdate species.  相似文献   

The compositional classification of chondrites: IV. Ungrouped chondritic meteorites and clasts     

Gregory W. Kallemeyn  John T. Wasson 《Geochimica et cosmochimica acta》1985,49(1):261-270

Six specimens of unusual chondritic materials were analyzed by neutron activation for 30 elements in order to assess their degree of chondritic compositional pristinity and to search for evidence of genetic links to other chondrites. Five have highly recrystallized textures; the other, the Cumberland Falls chondrite, has suffered minor metamorphic recrystallization. Acapulco and Allan Hills A77081, are closely related and have subpristine compositions; they are more distantly related to Enon which has an altered composition. Udei Station appears to be a IAB meteorite even though its $\text{FeO}\text{(FeO + MgO)}$ ratio is slightly above the IAB field. The highly weathered meteorite Tierra Bianca is closely related to IAB but has a δ¹⁸O value 5 standard deviations higher than the IAB mean and is designated ungrouped. Udei Station and Tierra Bianca have altered compositions; rare earth element patterns indicate loss of a phosphate phase. The elemental composition of the Cumberland Falls chondrite is virtually identical to that of LL chondrites and its O-isotope composition is closely similar to those of some unequilibrated ordinary chondrites including LL Semarkona. The $\text{FeO}\text{(FeO + MgO)}$ ratios in its olivine are generally much lower than those in pyroxene, a relationship we show to be indicative of in situ reduction resulting from exchange with the aubritic host. The names winonaites and forsterite chondrites have no taxonomic utility.  相似文献   

Anomalies in rare earth distributions in seawater: Gd and Tb     

Hein J.W. De Baar  Peter G. Brewer  Michael P. Bacon 《Geochimica et cosmochimica acta》1985,49(9):1961-1969

We have measured profiles of the rare earth elements (REE) in Atlantic and Pacific Ocean waters. The data, normalized versus shales, exhibit a pronounced anomaly in Gd relative to its neighbors Eu and Tb in the REE series such that the Gd concentrations are high by 30–50%. Closer inspection reveals that the anomaly is made up of both elevated Gd and depressed Tb concentrations, likely associated with solution chemistry shifts in the transition from an exactly half filled 4f electron shell. Anomalies in Gd and Tb solution complexation are also indicated by the Turner-Whitfield-Dickson speciation model. The overall trend of heavy REE(III) enrichment in seawater and the $\text{Gd}\text{Tb}$ anomaly described here tend to support scavenging as an important removal mechanism for the REE from seawater.  相似文献