排序方式： 共有6条查询结果，搜索用时 15 毫秒
1
1.
New Thorium Isotope Ratio Measurements in Silicate Reference Materials: A‐THO,AGV‐2, BCR‐2, BE‐N,BHVO‐2 and BIR‐1 
下载免费PDF全文
下载免费PDF全文 Marion Carpentier Abdelmouhcine Gannoun Christian Pin Olgeir Sigmarsson 《Geostandards and Geoanalytical Research》2016,40(2):239-256
A two‐step Th isolation protocol, involving micro‐columns of TRU‐Spec extraction chromatography material and AG1 resin, was evaluated. The MC‐ICP‐MS procedure included 232Th tailing characterisation and correction, and calibrator bracketing using an in‐house standard solution (ThS1) to correct for instrumental mass bias and Faraday cup to secondary electron multiplier relative gain. Repeated analyses of reference solutions (UCSC Th ‘A’, WUN, OU Th ‘U’, IRMM‐36) were consistent with published data. Six reference materials (A‐THO, BCR‐2, AGV‐2, BHVO‐2, BE‐N and BIR‐1) were processed. The average 230Th/232Th values obtained for these samples are in excellent agreement with published data. In addition, we report the first 230Th/232Th values for BE‐N and BIR‐1. The intermediate precisions for rock samples ranged from ± 0.24 to ± 0.49% (2 RSD) and were similar to those achieved for synthetic solutions, thereby supporting the overall validity of the chemical separation, data acquisition and reduction procedures. Counting statistics on the 230Th isotope was the most significant source of uncertainty. The intermediate precision of the mean 230Th/232Th for the Th‐depleted BIR‐1 (5.64 × 10?6 ± 0.27%, 2 RSD) is in the range of the analyses of other reference materials analysed in this study. 相似文献
2.
Sr and Pb isotopic composition of five USGS glasses (BHVO-2G, BIR-1G, BCR-2G, TB-1G, NKT-1G) 总被引：2，自引：0，他引：2
Marlina Elburg Pieter Vroon Bas van der Wagt Arnaud Tchalikian 《Chemical Geology》2005,223(4):196-207
Sr isotopic compositions and Rb / Sr ratios of three USGS glasses (BHVO-2G, BIR-1G, BCR-2G) are identical to those of the original USGS reference materials. NKT-1G and TB-1G give values of 0.70351 and 0.70558, respectively. Pb isotopic ratios were measured by the standard-sample bracketing technique on an MC-ICP-MS, which give results that are comparable in accuracy and reproducibility to double spike analyses. However, assessment of the reproducibility of the technique is hampered by inhomogeneous contamination of all USGS reference materials analysed. This contamination is likely to be the reason why the USGS glasses do not all have the same Pb isotopic composition as their unfused originals. Powdered glasses, distributed for characterisation of the glasses by bulk analytical techniques, do not all have the same Pb isotopic compositions as the solid glass material, and can therefore not be used for this purpose. 相似文献
3.
鸟瞰航摄历史遗迹景观的技术分析 总被引：2，自引：0，他引：2
介绍了国内利用超轻型飞机航空摄影考古的首次试验,通过对历史遗迹的分析,取得良好的应用效果。本次试验采用国产的超轻型飞机蓝鹰AD-200Y型,携带常规照相机,在内蒙古自治区以呼和浩特市为中心的局部地区,进行20个架次飞行,从低航空高度环绕历史遗迹,多角度视野,进行航拍鸟瞰地表历史遗迹景观照片799张。这些照片反映历史遗迹的整体面貌,是地面田野考古无法做到的事。为考古研究提供了不可多得的资料。其技术工艺流程：①确定历史遗迹项目；②地形图分析历史遗迹基础地理环境(地理位置,地形地貌)；③分析交通气象状况；④航空摄影技术设计；⑤超轻型飞机技术完善；⑥照相机和胶卷选型；⑦拟定飞行安全措施；⑧飞行基地起降跑道选择；⑨航摄飞行实施和指挥；⑩历史遗迹鸟瞰景观数字化图像分析。 相似文献
4.
5.
The geochemistry of Re-Os and the recent use of Re as a non-traditional stable isotope both need accurate and precise quantification of 187 Re/185 Re ratios. This paper reports rhenium isotopic data obtained from the analysis of a standard solution and geological samples by MC-ICP-MS. We show that measured isotopic ratios are modified by matrix effects that cannot be accounted for by the standard solution bracketing technique. The bias resulting from measurements on a spiked (185 Re-enriched) sample is shown to alter the apparent Re concentration by several percent. When spiking samples and calibrators with tungsten, simultaneous measurement of tungsten and rhenium isotopes compensates for the matrix-induced modification of mass bias. Rhenium and tungsten are shown to have different fractionation factors. This may be due to the fact that the two elements fractionate in a different but systematic way, or that the reference isotopic ratios used for elemental Re and W are incoherent with one another. The consistency of fractionation through time can be used to obtain an empirical relationship between W and Re measured ratios from a standard solution to obtain a sample's fractionation-corrected 187 Re/185 Re spiked ratio on samples containing pg g−1 levels of Re, even if some matrix capable of affecting mass bias remains in the final solution. 相似文献
6.
1