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1.
A measurement procedure for determining of Ru, Pd, Ir, Pt and Au mass fractions in ferromanganese deposits by inductively coupled plasma‐mass spectrometry after acid digestion and anion exchange preconcentration is presented. To eliminate incomplete recovery after sorption preconcentration of the platinum‐group elements (PGE) and Au, a standard addition method was used. Detection limits ranged from 0.02 ng (Pd, Ir) to 0.19 ng (Ru). The measurement results for ferromanganese nodule reference material NOD‐A‐1 and NOD‐P‐1 agree with earlier reported values. Intermediate precision of PGE concentration data for nodule reference materials in this work was 5–24% (1s) and could reflect sample heterogeneity.  相似文献   

2.
In this paper, the analytical dual‐porosity dual‐permeability poromechanics solution for saturated cylinders is extended to account for electrokinetic effects and material transverse isotropy, which simulate the responses of chemically active naturally fractured shale under time‐dependent mechanical loading and ionic solution exposure. The solution addresses the stresses, fracture pore pressure, matrix pore pressure, fluid fluxes, ion concentration evolution, and displacements due to the applied stress, pore pressure, and solute concentration difference between the sample and the circulation fluid. The presented solution will not only help validate numerical simulations but also assist in calibrating and interpreting laboratory results on dual‐porosity dual‐permeability shale. It is recommended that the analytical solutions of radial and axial displacements be used to match the corresponding laboratory‐recorded data to determine shale dual permeability and chemo‐electrical parameters including membrane coefficient, ions diffusion coefficients, and electro‐osmotic permeability.  相似文献   

3.
Lithium separation technique for three reference materials has been established together with precise determination of lithium isotope using a Neptune multi collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). The solutions of lithium element standard reference materials, potassium, calcium, sodium, magnesium and iron single element, were used to evaluate analytical methods applied. Three separate stages of ion-exchange chromatography were carried out using organic cation-exchange resin (AG 50W-X8). Lithium was enriched for the three stages using different eluants, which are 2.8 M HCl, 0.15 M HCl and 0.5 M HCl in 30% ethanol, respectively. The columns for the first and second stages are made of polypropylene, and those for the third stage are made of quartz. Total reagent volume for the entire chemical process was 35 mL for three reference materials. The recovery yielded for the three stages is 98.9–101.2% with an average of 100.0%, 97.6–101.9% with an average of 99.9%, and 99.8–103.3% with an average of 100.6%, respectively. The precision of this technique is conservatively estimated to be ±0.72–1.04‰ (2σ population), which is similar to the precision obtained by different authors in different laboratories with MC-ICP-MS. The δ7Li values (7Li/6Li relative to the IRMM-016 standard) determined for andesite (AGV-2) and basalt (BHVO-2) are 5.68‰ (n=18), 4.33‰ (n=18), respectively. The δ7Li value (7Li/6Li relative to the L-SVEC standard) determined for IRMM-016 is –0.01‰ (n=15). All these analytical results are in good agreement with those previously reported. In addition, the results for the same kinds of samples analyzed at the MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, are consistent with those obtained at the Plasma Laboratory, University of Maryland, within analytical uncertainty. According to these experiment results, it is concluded that this proposed procedure is a suitable method for determining the lithium isotopic composition of natural samples.  相似文献   

4.
Three synthetic reference glasses were prepared by directly fusing and stirring 3.8 kg of high‐purity oxide powders to provide reference materials for microanalytical work. These glasses have andesitic major compositions and are doped with fifty‐four trace elements in nearly identical abundance (500, 50, 5 µg g?1) using oxide powders or element solutions, and are named ARM‐1, 2 and 3, respectively. We further document that sector‐field (SF) ICP‐MS (Element 2 or Element XR) is capable of sweeping seventy‐seven isotopes (from 7Li to 238U, a total of sixty‐eight elements) in 1 s and, thus, is able to quantify up to sixty‐eight elements by laser sampling. Micro‐ and bulk analyses indicate that the glasses are homogeneous with respect to major and trace elements. This paper provides preliminary data for the ARM glasses using a variety of analytical techniques (EPMA, XRF, ICP‐OES, ICP‐MS, LA‐Q‐ICP‐MS and LA‐SF‐ICP‐MS) performed in ten laboratories. Discrepancies in the data of V, Cr, Ni and Tl exist, mainly caused by analytical limitations. Preliminary reference and information values for fifty‐six elements were calculated with uncertainties [2 relative standard error (RSE)] estimated in the range of 1–20%.  相似文献   

5.
This article proposes a methodology to analyse the composition of very small carbonate samples such as larval fish otoliths. The chemical composition of otoliths, which are carbonate structures in the inner ear, is often used to explore population dynamics in fishes. Recent advances in laser ablation‐inductively coupled plasma‐mass spectrometry have suggested its potential application to this field. In this study, analyses were performed using a 193 nm ArF Resonetics LA system, coupled to an Agilent 7700X‐ICP‐MS, with the following ablation parameters: a beam diameter of 5 μm, energy of 3 mJ, 2.7 J cm?2, laser repetition rate of 10 Hz and translation speed of 2.5 μm s?1. NIST SRM 610 glass was used as the primary calibration material. Performing this protocol, characterisation of a USGS GP‐4 reference material was achieved with suitable precision and accuracy, but the USGS MACS‐3 reference material appeared more heterogeneous under the ablation conditions tested. Calibration was performed using two different beam diameters (5 and 11 μm). Capelin (Mallotus villosus) otoliths measuring between 10 and 20 μm in diameter were tested. Even though a smaller beam diameter and lower energy were used compared with those normally employed to analyse larger otoliths, the method was successful.  相似文献   

6.
Viscoelastic or creep behaviour can have a significant influence on the load transfer (t–z) response at the pile–soil interface, and thus on the pile load settlement relationship. Many experimental and theoretical models for pile load transfer behaviour have been presented. However, none of these has led to a closed‐form expression which captures both non‐linearity and viscoelastic behaviour of the soil. In this paper, non‐linear viscoelastic shaft and base load transfer (t–z) models are presented, based on integration of a generalized viscoelastic stress–strain model for the soil. The resulting shaft model is verified through published field and laboratory test data. With these models, the previous closed‐form solutions evolved for a pile in a non‐homogeneous media have been readily extended to account for visco‐elastic response. For 1‐step loading case, the closed‐form predictions have been verified extensively with previous more rigorous numerical analysis, and with the new GASPILE program analysis. Parametric studies on two kinds of commonly encountered loading: step loading, ramp (linear increase followed by sustained) loading have been performed. Two examples of the prediction of the effects of creep on the load settlement relationship by the solutions and the program GASPILE, have been presented. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

7.
In this study, we report both 143Nd/144Nd and 147Sm/144Nd values in twelve minerals (apatite, titanite, monazite and eudialyte) based on analyses over 4 years using LA‐MC‐ICP‐MS. The positive correlation between the measured βSm and βNd (r2 = 0.9981) over this time in our laboratory demonstrates the excellent long‐term stability of the method. Compared with the normal method, Sm and Nd signal intensities were improved by a factor of 2.9 with the use of X skimmer and Jet sample cones in combination with the addition of nitrogen at 3–6 ml min?1 to the central gas flow. The enhancement of signal intensity benefits the accurate in situ determination of the Sm‐Nd isotopes of samples poor in these elements. 143Nd/144Nd values were also determined in two manganese nodules and GSMC Co‐rich crust with low mass fractions of Nd (94–293 μg g?1). Generally, most of the obtained Sm‐Nd isotopic compositions in these geological materials are consistent with published values. ‘External reproducibility’ (2s) of 143Nd/144Nd and 147Sm/144Nd was typically better than 0.06‰ and 2.5‰, respectively, demonstrating that the Durango, Otter Lake, NW‐1 and MAD apatites, the Khan, and OLT‐1 titanites, MGMH#117531 monazite and LV01 eudialyte are promising candidate reference materials for in situ Sm‐Nd isotopic determinations. The Trebilcock, Mae Klang and 44069 monazites are only suitable for in situ Nd isotopic determinations because of their heterogeneous Sm/Nd compositions. The heterogeneous Sm‐Nd composition of titanite BLR‐1 demonstrates that it is not a suitable reference material for in situ Sm‐Nd isotopic determinations. Deep‐sea samples (NOD‐A‐1 and NOD‐P‐1 manganese nodule, GSMC Co‐rich crust) with low mass fractions of Nd also show homogenous Nd isotopic compositions. Sm‐Nd isotopic ratios of a monazite (MQG‐22) from the North China Craton were measured as a case study and gave a 147Sm‐143Nd isochron age of 1792 ± 35 Ma (MSWD = 3.2) consistent with the published metamorphic age of the host metasedimentary rocks. The results for both candidate reference materials and geological samples demonstrate that the in situ LA‐MC‐ICP‐MS analytical protocol described is feasible and robust for research in geological evolution.  相似文献   

8.
Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti‐in‐quartz (TitaniQ) geothermometer applicable to geological conditions up to ~ 20 kbar. We present a new method for determining 48Ti mass fractions in quartz by LA‐ICP‐MS at the 1 μg g?1 level, relevant to quartz in HP‐LT terranes. We suggest that natural quartz such as the low‐CL rims of the Bishop Tuff quartz (determined by EPMA; 41 ± 2 μg g?1 Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are insignificant, thus allowing for the use of 48Ti as a normalising mass. Average titanium mass fraction from thirty‐three analyses of low temperature quartz from the Czech Erzgebirge is 0.9 ± 0.2 μg g?1 (2s) using 48Ti as a normalising mass and Bishop Tuff quartz rims as a reference material. The 2s average analytical uncertainty for individual analyses of 48Ti is 8% for 50 μm spots and 7% for 100 μm spots, which offers much greater accuracy than the 21–41% uncertainty (2s) incurred from using 49Ti as an analyte.  相似文献   

9.
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10.
Matrix‐matched reference materials are necessary for accurate microbeam U‐Pb dating and Hf isotopic determination. This study introduces the RMJG rutile as a new potential reference material, which was separated from Palaeoproterozoic pelitic granulites collected in Hebei Province, China. LA‐ICP‐MS measurements indicate the RMJG rutile has extremely low Th (< 0.003 ± 0.01 µg g?1) and common Pb contents, but high Hf (102 ± 34 µg g?1), U (61 ± 11 µg g?1), and radiogenic Pb (~ 20 µg g?1) contents. Moreover, the rutile yields relatively constant U‐Pb ages and Hf isotopic data. The LA‐ICP‐MS analyses suggest that this rutile has a concordant U‐Pb age with a statistical mean 206Pb/238U and 207Pb/235U ages of 1749.9 ± 32.1 Ma and 1750.0 ± 26.4 Ma, respectively (2s), which are statistically indistinguishable from its ID‐TIMS ages (1750.6 ± 8.4 and 1750.1 ± 4.7 Ma). Precise determination of the 176Hf/177Hf ratio by MC‐ICP‐MS in solution mode (0.281652 ± 0.000006) is in good agreement with the statistical mean of the LA‐MC‐ICP‐MS measurements (0.28166 ± 0.00018). Therefore, the limited variations of RMJG U‐Pb age and Hf isotopic composition together with its extremely low common Pb and high Hf, U and Pb contents make it an ideal calibration and monitor reference material for LA‐ICP‐MS measurements.  相似文献   

11.
To assess the homogeneity of and provide the first Sr‐Nd‐Hf‐Pb isotopic reference values for the Chinese Geological Standard Glasses CGSG‐1, CGSG‐2, CGSG‐4 and CGSG‐5, we measured these isotopes in several measurement sessions over the course of nearly 3 years. The results were obtained by high‐precision MC‐ICP‐MS and TIMS. Our investigation indicates that these CGSG glass reference materials are homogenous with regard to Sr‐Nd‐Hf‐Pb isotopic distribution and are therefore suitable geochemical materials for Sr‐Nd‐Hf‐Pb isotope measurements. Clear differences in Sr‐Nd‐Hf‐Pb isotopic composition were observed between the glasses and the original powdered rock reference materials (CGSG‐2 and GSR‐7, and especially CGSG‐5 and GSR‐2) because of flux addition during preparation of the glasses. The new Sr‐Nd‐Hf‐Pb isotope data provided here might be useful to the geochemical community for in situ and bulk analysis.  相似文献   

12.
The three‐dimensional disposition of cordierite and biotite crystals in a hornfels from the contact aureole of the Bugaboo Batholith is quantified using high‐resolution X‐ray micro‐computed tomography and global as well as scale‐dependent pattern statistics. The results demonstrate a random distribution of cordierite and biotite crystal sizes for all scales across the entire rock volume studied indicative of interface‐controlled prograde metamorphic reaction kinetics. The reaction considered responsible for the mineral assemblage and the formation of cordierite and biotite in the hornfels is Ms + Chl + Qtz = Crd + And + Bt + . Rock‐specific phase equilibria point to metamorphic conditions of ~520 –550 °C and 3 kbar for this reaction. The common approach to approximate the shape of crystals as spherical underestimates the influence of the Strauss hard‐core process on rock texture and may be misinterpreted to reflect ordering of crystal sizes by inhibition of nucleation and growth commonly associated with diffusion‐controlled reaction kinetics. According to our findings, Strauss hard‐core ordering develops at length scales equal to and less than the average major axis of the crystal population. This is significantly larger than what is obtained if a spherical crystal geometry would be assumed, and increases with deviation from sphericity. For the cordierite and biotite populations investigated in this research, Strauss hard‐core ordering developed at length scales of up to ～2.2 and 1.25 mm, respectively, which is almost 1 mm longer than the scales that would be obtained if a spherical geometry would have been assumed. Our results highlight the importance of a critical assessment of the geometrical model assumptions commonly applied in the three‐dimensional analysis of crystal size distributions, and underline the need for a quantitative understanding of interface processes in order to appreciate their role in the kinetics of contact metamorphic reactions and rock texture formation.  相似文献   

13.
Niobium and Ta concentrations in MPI‐DING and USGS (BCR‐2G, BHVO‐2G, BIR‐1G) silicate rock glasses and the NIST SRM 610–614 synthetic soda‐lime glasses were determined by 193 nm ArF excimer laser ablation and quadrupole ICP‐MS. Measured Nb and Ta values of MPI‐DING glasses were found to be consistently lower than the recommended values by about 15% and 25%, respectively, if calibration was undertaken using commonly accepted values of NIST SRM 610 given by Pearce et al. Analytical precision, as given by the 1 s relative standard deviation (% RSD) was less than 10% for Nb and Ta at concentrations higher than 0.1 μg g?1. A significant negative correlation was found between logarithmic concentration and logarithmic RSD, with correlation coefficients of ‐0.94 for Nb and ‐0.96 for Ta. This trend indicates that the analytical precision follows counting statistics and thus most of the measurement uncertainty was analytical in origin and not due to chemical heterogeneities. Large differences between measured and expected Nb and Ta in glasses GOR128‐G and GOR132‐G are likely to have been caused by the high RSDs associated with their very low concentrations. However, this cannot explain the large differences between measured and expected Nb and Ta in other MPI‐DING glasses, since the differences are normally higher than RSD by a factor of 3. Count rates for Nb and Ta, normalised to Ca sensitivity, for the MPI‐DING, USGS and NIST SRM 612–614 glasses were used to construct calibration curves for determining NIST SRM 610 concentrations at crater diameters ranging from 16 (im to 60 μm. The excellent correlation between the Nb/Ca1μgg‐1 signal (Nb represents the Nb signal intensity; Ca1μg g‐1 represents the Ca sensitivity) and Nb concentration, and between the Ta/Ca1μg g‐1 signal (where Ta represents the Ta signal intensity; Ca1μg g‐1 represents the Ca sensitivity) and Ta concentration (R2= 0.9992–1.00) in the various glass matrices suggests that matrix‐dependent fractionation for Nb, Ta and Ca was insignificant under the given instrumental conditions. The results confirm that calibration reference values of Nb and Ta in NIST SRM 610 given by Pearce et al. are about 16% and 28% lower, respectively. We thus propose a revision of the preferred value for Nb from 419.4 ± 57.6 μg g?1 to 485 ± 5 μg g?1 (1 s) and for Ta from 376.6 ± 77.6 μg g?1 to 482 ± 4 μg g?1 (Is) in NIST SRM 610. Using these revised values for external calibration, most of the determined average values of MPI‐DING, USGS and NIST SRM 612–614 reference glasses agree within 3% with the calculated means of reported reference values. Bulk analysis of NIST SRM 610 by standard additions using membrane desolvation ICP‐MS gave Nb = 479 ± 6 μg g?1 (1 s) and Ta = 468 ± 7 μg g?1 (1 s), which agree with the above revised values within 3%.  相似文献   

14.
We present multitechnique U‐Pb geochronology and Hf isotopic data from zircon separated from rapakivi biotite granite within the Eocene Golden Horn batholith in Washington, USA. A weighted mean of twenty‐five Th‐corrected 206Pb/238U zircon dates produced at two independent laboratories using chemical abrasion‐isotope dilution‐thermal ionisation mass spectrometry (CA‐ID‐TIMS) is 48.106 ± 0.023 Ma (2s analytical including tracer uncertainties, MSWD = 1.53) and is our recommended date for GHR1 zircon. Microbeam 206Pb/238U dates from laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and secondary ion mass spectrometry (SIMS) laboratories are reproducible and in agreement with the CA‐ID‐TIMS date to within < 1.5%. Solution multi‐collector ICP‐MS (MC‐ICP‐MS) measurements of Hf isotopes from chemically purified aliquots of GHR1 yield a mean 176Hf/177Hf of 0.283050 ± 17 (2s, n = 10), corresponding to a εHf0 of +9.3. Hafnium isotopic measurements from two LA‐ICP‐MS laboratories are in agreement with the solution MC‐ICP‐MS value. The reproducibility of 206Pb/238U and 176Hf/177Hf ratios from GHR1 zircon across a variety of measurement techniques demonstrates their homogeneity in most grains. Additionally, the effectively limitless reserves of GHR1 material from an accessible exposure suggest that GHR1 can provide a useful reference material for U‐Pb geochronology of Cenozoic zircon and Hf isotopic measurements of zircon with radiogenic 176Hf/177Hf.  相似文献   

15.
The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton(NCC) remain unclear whether the protolith was sourced from ultramafic rocks or chemical sedimentary sequences. Here we present integrated petrographic and geochemical studies to characterize the protoliths and to gain insights on the ore-forming processes. Iron ores mainly contain low-Ti magnetite(TiO_2 ~0.1 wt%) and serpentine(Mg#=92.42–96.55), as well as residual olivine(Fo=89–90), orthopyroxene(En=89–90) and hornblende. Magnetite in the iron ores shows lower Al, Sc, Ti, Cr, Zn relative to that from ultramafic Fe-Ti-V iron ores, but similar to that from metamorphic chemical sedimentary iron deposit. In addition, interstitial minerals of dolomite, calcite, apatite and anhydrite are intergrown with magnetite and serpentine, revealing they were metamorphic, but not magmatic or late hydrothermal minerals. Wall rocks principally contain magnesian silicates of olivine(Fo=83–87), orthopyroxene(En=82–86), humite(Mg#=82–84) and hornblende [XMg=0.87–0.96]. Dolomite, apatite and anhydrite together with minor magnetite, thorianite(Th-rich oxide) and monazite(LREE-rich phosphate) are often seen as relicts or inclusions within magnesian silicates in the wall rocks, revealing that they were primary or earlier metamorphic minerals than magnesian silicates. And olivine exists as subhedral interstitial texture between hornblende, which shows later formation of olivine than hornblende and does not conform with sequence of magmatic crystallization. All these mineralogical features thus bias towards their metamorphic, rather than magmatic origin. The dominant chemical components of the iron ores are SiO_2(4.77–25.23 wt%), Fe_2O_3 T(32.9–80.39 wt%) and MgO(5.72–27.17 wt%) and uniformly, those of the wall rocks are also SiO_2(16.34–48.72 wt%), Mg O(16.71–33.97 wt%) and Fe_2O_3 T(6.98–30.92 wt%). The striking high Fe-Mg-Si contents reveal that protolith of the Zhaoanzhuang iron deposit was more likely to be chemical sedimentary rocks. The distinct high-Mg feature and presence of abundant anhydrite possibly indicate it primarily precipitated in a confined seawater basin under an evaporitic environment. Besides, higher contents of Al, Ti, P, Th, U, Pb, REE relative to other Precambrian iron-rich chemical precipitates(BIF) suggest some clastic terrestrial materials were probably input. As a result, we think the Zhaoanzhuang iron deposit had experienced the initial Fe-Mg-Si marine precipitation, followed by further Mg enrichment through marine evaporated process, subsequent high-grade metamorphism and late-stage hydrothermal fluid modification.  相似文献   

16.
Mineral inclusions are ubiquitous in metamorphic rocks and elastic models for host‐inclusion pairs have become frequently used tools for investigating pressure–temperature (P–T) conditions of mineral entrapment. Inclusions can retain remnant pressures () that are relatable to their entrapment P–T conditions using an isotropic elastic model and P–T–V equations of state for host and inclusion minerals. Elastic models are used to constrain P–T curves, known as isomekes, which represent the possible inclusion entrapment conditions. However, isomekes require a temperature estimate for use as a thermobarometer. Previous studies obtained temperature estimates from thermometric methods external of the host‐inclusion system. In this study, we present the first P–T estimates of quartz inclusion entrapment by integrating the quartz‐in‐garnet elastic model with titanium concentration measurements of inclusions and a Ti‐in‐quartz solubility model (QuiG‐TiQ). QuiG‐TiQ was used to determine entrapment P–T conditions of quartz inclusions in garnet from a quartzofeldspathic gneiss from Goodenough Island, part of the (ultra)high‐pressure terrane of Papua New Guinea. Raman spectroscopic measurements of the 128, 206, and 464 cm?1 bands of quartz were used to calculate inclusion pressures using hydrostatic pressure calibrations (), a volume strain calculation (), and elastic tensor calculation (), that account for deviatoric stress. values calculated from the 128, 206, and 464 cm?1 bands’ hydrostatic calibrations are significantly different from one another with values of 1.8 ± 0.1, 2.0 ± 0.1, and 2.5 ± 0.1 kbar, respectively. We quantified elastic anisotropy using the 128, 206 and 464 cm?1 Raman band frequencies of quartz inclusions and stRAinMAN software (Angel, Murri, Mihailova, & Alvaro, 2019,  234 :129–140). The amount of elastic anisotropy in quartz inclusions varied by ~230%. A subset of inclusions with nearly isotropic strains gives an average and of 2.5 ± 0.2 and 2.6 ± 0.2 kbar, respectively. Depending on the sign and magnitude, inclusions with large anisotropic strains respectively overestimate or underestimate inclusion pressures and are significantly different (<3.8 kbar) from the inclusions that have nearly isotropic strains. Titanium concentrations were measured in quartz inclusions exposed at the surface of the garnet. The average Ti‐in‐quartz isopleth (19 ± 1 ppm [2σ]) intersects the average QuiG isomeke at 10.2 ± 0.3 kbar and 601 ± 6°C, which are interpreted as the P–T conditions of quartzofeldspathic gneiss garnet growth and entrapment of quartz inclusions. The P–T intersection point of QuiG and Ti‐in‐quartz univariant curves represents mechanical and chemical equilibrium during crystallization of garnet, quartz, and rutile. These three minerals are common in many bulk rock compositions that crystallize over a wide range of P–T conditions thus permitting application of QuiG‐TiQ to many metamorphic rocks.  相似文献   

17.
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18.
This paper is intended to give some information about how to build a model necessary for bending analysis of rectangular and circular plates resting on a two‐parameter elastic foundation, subjected to combined loading and permitting various types of boundary conditions. The formulation of the problem takes into account the shear deformation of the plate and the surrounding interaction effect outside the plate. The numerical model based on an 18‐node zero‐thickness isoparametric interface element interacting with a thick Reissner–Mindlin plate element with three degrees of freedom at each of the nine nodes, which enforce C0 continuity requirements for the displacements and rotations of the midsurface, is proposed. Stiffness matrices of a special interface element are superimposed on the global stiffness matrix to represent the stiffening elastic foundation under and beyond the plate. Some numerical examples are given to illustrate the advantages of the method presented. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

19.
In this contribution, we report Hf isotopic data and Lu and Hf mass fractions for thirteen Chinese rock reference materials (GBW07 103–105, 109–113 and 121–125, that is GSR 1–3, 7–11 and 14–18, respectively) that span a broad compositional range. Powdered samples were spiked with a 176Lu‐180Hf enriched tracer and completely digested using conventional HF, HNO3 and HClO4 acid dissolution protocols. Fluoride salts were dissolved during a final H3BO3 digestion, and chemical purification was performed using a single Ln resin. All measurements were carried out on a MC‐ICP‐MS. This work provides the first comprehensive report of the Lu‐Hf isotopic composition of Chinese geochemical rock reference materials, and results indicate that they are of comparable quality to the well‐characterised and widely used USGS and GSJ rock reference materials.  相似文献   

20.
The anomaly response characteristics of the vertical line‐source 3D borehole‐to‐surface model are simulated by an adaptive finite element method. The calculation shows that the anomaly in the radial direction is pressed and the closer to the source, the more pronounced, the anomaly is stretched in the direction perpendicular to the radius. Adding a B pole in the Y direction can offset the effect of stretching to some extent. The anomaly that is closer to the source of the profile is clearer than the anomaly that is far from the source. The research results are of great significance for guiding the practical application of the borehole‐to‐surface electrical method.  相似文献   

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