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1.
Two reference samples, Albite AL-I and Iron Formation sample IF-G were analysed for their chemical composition by the International Working Group "Analytical Standards of Minerals, Ores and Rocks" (GIT-IWG). AL-I was processed in 189 kg and IF-G and 760 kg. 103 GIT-IWG laboratories participated in this collaborative study along with 171 geoanalysts. This study lasted 15 months (September 1982 - December 1983) and is the second undertaken by the GIT-IWG. Over 2400 units of data were collated. As a result of this international study, the major and minor elements have been well characterized in both the samples; however, more data on trace elements will be very welcome for a better definition of trace elements, although working values have been proposed for about forty trace elements in each sample. The first and the second collaborative studies undertaken by GIT-IWG demonstrate well the immense analytical potential of the GIT-IWG.  相似文献   

2.
The "Five-Mode Method" for evaluation of compiled data has been applied to three well-established GIT-IWG rock reference samples: Anorthosite AN-G, Basalt BE-N and Granite MA-N. Results are compared to the accepted values, and where the two values are not in accord, a new procedure, the Graphical Moving Mode, is introduced. It is used to provide a clearer picture of the nature of the distribution of the raw data for each constituent, and, possibly to demonstrate the advantages of using the modal approach.  相似文献   

3.
The selenium content of fifty two geochemical reference samples, issued by several reference material producers (ANRT, GIT-IWG, USGS, NIST and GSJ) has been determined by continuous hydride generation and atomic absorption spectrometry. Selenium(VI) in the digested solutions was pre-reduced to selenium(IV) by heating in 6 mol l−1 HCl solution. The limit of detection was 3 ng g−1 selenium in common geological samples. Some samples which contain a large amount of heavy metals were analysed by the standard addition technique. The agreement between the reported results and published data is satisfactory.  相似文献   

4.
The concentrations of 26 elements have been investigated in seven BCS certified reference samples using three varieties of neutron activation analysis. The ANRT granite GS-N was used as the comparator reference material while the USGS basalt BHVO-1 and the GIT-IWG basalt BE-N were analysed concurrently to assess the analytical accuracy.  相似文献   

5.
The molybdenum (Mo) contents of fifty three geochemical reference materials issued by ANRT, GIT-IWG, NIST and GSJ, have been determined by atomic absorption spectrometry, using a graphite furnace atomiser, after extraction of Mo dithiol with isoamyl acetate. Detection limits for this method (0.01 μg g−1) are ten times smaller than for most classical methods. The agreement between the present results and published data is satisfactory.  相似文献   

6.
This compilation report describes the field location, mineralogy, preparation and homogeneity testing of two new GIT-IWG reference materials: Whin Sill dolerite (WS-E) from England and Pitscurrie microgabbro (PM-S) from Scotland. The elemental composition of these two new reference materials has been established by an international cooperative analysis programme involving participation by 104 laboratories. A full assessment of these analytical results is presented, from which working values have been derived for the major elements as well as for 45 trace elements in WS-E and 44 trace elements in PM-S. Furthermore, isotopic ratios are presented for both samples, particularly for 87Sr/86Sr and 143Nd/144Nd.  相似文献   

7.
Abbey's select laboratories method has been applied to the reported data for major and minor elements in the proposed GIT-IWG reference sample IF-G. The final values obtained by this method have been compared with the recommended values published by Govindaraju in 1984. Slightly different percentages are suggested for MgO, K2O and Fe2O3T. The importance of applying the Abbey method by participants in co-operative studies is emphasized. Such an application gives a better understanding of data treatment and of the degree of reliability of published final values; furthermore the objective score obtained for laboratory quality will stimulate participating laboratories to improve their analytical methods and procedures. As an illustration some improvements in the laboratory of the authors are mentioned.  相似文献   

8.
We have developed a new database named GeoReM ( http://georem.mpch-mainz.gwdg.de ) for reference materials and isotopic standards of geochemical and mineralogical interest. Reference samples include rock powders originating from the USGS, GSJ, GIT-IWG, synthetic and natural reference glasses originating from NIST, USGS, MPI-DING, as well as mineral (e.g., 91500 zircon), isotopic (e.g., La Jolla, E&A, NIST SRM 981), river water and seawater reference materials. GeoReM is a relational database, which strongly follows the concept of the three EARTHCHEM databases. It contains published analytical and compilation values (major and trace element concentrations, radiogenic and stable isotope ratios), important metadata about the analytical values, such as uncertainty, uncertainty type, method and laboratory. Sample information and references are also included. Three different ways of interrogating the database are possible: (1) sample names or material types, (2) chemical criteria and (3) bibliography. Some typical applications are described. GeoReM currently (October 2005) contains more than 750 geological reference materials, 6000 individual sets of results and references to 650 publications.  相似文献   

9.
The indium (In) and tellurium (Te) contents of fifty nine geological reference materials, issued by several reference material producers (USGS, CRPG, ANRT, GIT-IWG and GSJ) have been determined by graphite furnace atomic absorption spectrometry, after aqua regia and HF digestion, and extraction of iodide complexes with trioctylmethylammonium (TOMA) - metyl isobutyl ketone (MIBK). Although the interferences from most elements can be minimised by the addition of palladium solution as the matrix modifier, large concentrations of Bi, Cu, Pb or Sn suppress the absorbance of In and/or Te. Samples for analysis were therefore restricted to those in which the concentrations of these interfering elements did not cause a significant interference. The limit of detection was 0.2 ng g−1 In and Te for 1 g test portions. The agreement between the reported results and published data is satisfactory.  相似文献   

10.
Abundances of twenty four trace elements, including Y and fourteen rare earth elements (REE), are reported for eighty six geological reference materials and four proficiency testing samples. Analytical data were obtained by ICP-MS using solution nebulisation after mixed acid digestion (HF-HClO4) under pressure. Analysed samples cover a wide range of element concentrations and mineralogical compositions, including samples for which there are few previously published data. Precision for elemental determinations in nearly 90% of the samples analysed is better than 5%. Accuracy, estimated by comparison with data from compilations is better than 6% for well characterized reference materials. Results obtained for samples that are low in trace elements are often significantly lower than compiled reference values. A critical discussion of the compiled data sets, especially for Y and the REEs, indicates that some reference values seem to be erroneous.  相似文献   

11.
The report discusses some history of analytical problems that resulted in early standards. Geologic samples of economic interest and general information are discussed by country of origin, whereas geochemical samples are mentioned by samples types and by their intended use. Numerous topics and problems for reference samples and their data are discussed.  相似文献   

12.
Reliable rock reference materials for Au, Pd and Te are scarce. We report here our analytical data on these three elements in 46 NIM, IGGE and GSJ reference samples in order to accumulate analytical data on these samples.  相似文献   

13.
Two rock samples from the San Marcos Gabbro and the Lakeview Mountain Tonalite of the Southern California Batholith were prepared as U.S. Geological Survey reference samples. These samples were chosen to supply reference data for rocks having intermediate silica contents in the range of 45-60 percent. Unpublished data by members of the U.S. Geological Survey and some published data are summarized, and provisional estimates of the major and minor oxide and traceelement contents are given.  相似文献   

14.
All data reported by 200 analysts (106 laboratories) are presented for the four ANRT samples: Diorite DR-N, Serpentine UB-N, Bauxite BX-N and Disthène DT-N. Recommended values are given for the major and minor elements. As far as the as trace elements are concerned, DR-N has been characterized for 35 elements whereas the other three samples have been for only 20 elements. Wherever possible, brief comments have been inserted so as to explain our way of assigning recommended or proposed values.
After more than a decade of existence the total number of data reported for all the four samples reach only 3200 units which are not sufficient enough for a valid evaluation of compiled data. It is also pointed out that these samples are most likely to be available even during the next century as they have been prepared in large quantities of the order of one ton. A plea is therefore made for contribution of more data particularly for trace elements and for major elements which are present as trace elements in UB-N, BX-N and DT-N.  相似文献   

15.
Five samples from Suriname have been analysed for their chemical composition by 18 laboratories. The proposed reference samples are four soil samples and one lateritic bauxite. The samples were analyzed for major and minor elements as well as for 36 trace elements. More data are needed for better characterization of these samples, particularly for trace elements.  相似文献   

16.
New apatite (U-Th)/He (AHe) and apatite fission-track (AFT) data were acquired for cratonic basement samples from an 80 m span of drillcore in northeastern Kansas. The short depth interval over which the samples were collected indicates that they should have undergone thermal histories that would be indistinguishable using low temperature thermochronometry techniques. Individual AHe dates from four samples range from 99 to 464 Ma. Three samples yield dates <300 Ma that display a correlation with apatite eU (9-34 ppm) and a weaker correlation with grain size. eU concentration maps of apatites from these samples reveal low to moderate zonation in eU. Results for a fourth sample are characterized by dates >300 Ma, higher eU (39-113 ppm), and substantial data dispersion uncorrelated with eU and grain size. These apatites have strong and variable eU zonation. AFT dates for five samples range from 242 to 291 Ma. The sample with the highest eU apatites and oldest AHe dates yields the youngest AFT results. These results are “inverted”, with AHe dates distinctly older than the corresponding AFT date.We explore both the causes of data dispersion and the overall compatibility of this cratonic dataset. We find that geologically reasonable thermal histories can (1) explain the distribution of the moderate eU AHe data when accounting for the influence of radiation damage, grain size, and eU zonation on apatite He diffusivity, (2) reproduce the observed dispersion in the high eU AHe data when using a viable range of eU zonation and grain size, and (3) explain the AFT data for the same samples. The AHe and AFT data are mutually consistent, and viable thermal histories successfully predict the observed pattern of older AHe than AFT dates for the high eU apatites. Together these results suggest that appropriately accounting for the known controls on apatite He diffusivity can explain the observed dispersion and “inverted” AHe and AFT results in some thermochronometry datasets. A range of AHe dates should be especially common in cratonic data, because small differences in apatite He diffusivity are amplified by the thermal histories that typify cratonic settings. We use these results to develop some guidelines for interpreting dispersed AHe datasets. First, date-eU and date-grain size correlations should be evaluated, and if these patterns occur they can be used to better resolve the thermal history. Second, for samples that yield inexplicably large dispersion of AHe dates uncorrelated with eU and crystal size, the appropriate strategy is either to reject these samples from the suite used for thermal history interpretation or to acquire additional data to help decipher the significance of the age distribution.  相似文献   

17.
Since 1967–68, two mica reference samples, Biotite Mica-Fe and Phlogopite Mica-Mg, were made available to several geochemical laboratories. The analytical data reported during the past ten years by 142 geoanalysts belonging to 74 international laboratories are presented and assessed for deriving preferred values. Reaomrmended or proposed values are assigned for major, minor and several trace elements. The biotite Mica-Fe is better characterized for its chemical composition than the Phlogopite Mica-Mg. Both the samples are also proposed as geochronological standards. Because very few mica reference samples have been processed in large quantities, the international geochemiaal community is invited to contribute further useful data.  相似文献   

18.
Regional geochemical data from the 1:250,000 map series of Great Britain produced by the Institute of Geological Sciences are processed using a computer system developed for the National Geochemical Data Bank. The system, which can be used for the selective or complete retrieval of data and for statistical analysis and plotting, incorporates a procedure for determining accuracy and precision. Changes in accuracy are monitored by analysis of standards and the redetermination of sub-sets of samples using an instrumental neutron activation method. Samples are assigned random numbers in the field and are re-ordered sequentially prior to preparation and analysis in order to determine systematic errors occurring within batches of samples.Sampling, sub-sampling and analytical precision are monitored using analysis of variance methods on the results obtained on duplicate samples and analyses. The system for the efficient processing of this information is described and examples of the different types of error presented.  相似文献   

19.
沉积物中黑碳的提取和测定方法 : 误差分析和回收率实验   总被引：6，自引：0，他引：6  
介绍了从沉积物中提取黑碳的一种误差较小的改进方法，并对实验误差及引起误差的原因进行了详尽的分析和探讨，同时给出了方法的回收率。经过未均匀处理样品的平行实验，得到实验结果的总体偏差为8．89％，其中个别样品的偏差可达10％－20％；在样品进行了均匀处理后，得到平行实验的总体偏差为3．29％，HCl-HF单步处理的总体偏差为1．96％，而K2Cr2O7氧化处理单步实验的总体偏差为2．50％。其中回收率实验表明，黑碳的回收率可达80％以上。由此可见，所取样品具有代表性，是准确测定沉积物黑碳含量的前提。  相似文献   

20.
The preparation of two chromium ores as reference materials is described and the procedures used in the measurement of the homogeneity of the samples are outlined. Statistical analysis of the data submitted by 32 laboratories that resulted in the certification of the samples is presented. Certified values have been assigned for 11 constituents in the one sample and for 10 in the other sample. Provisional values have been assigned for FeO in both samples and CaO in one of the samples.  相似文献   

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