1,721,040 research outputs found
Comments on and re-evaluation of the paper “18O/16O ratio measurements of inorganic and organic materials by elemental analysis-pyrolysis-isotope ratio mass spectrometry continuous-flow techniques” by Fourel et al. (2011) Rapid Commun. Mass Spectrom. 25, 2691-2696
No full textOxygen and hydrogen isotope fractionation in precipitation. A simple approach for teaching
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Melt inclusions in minerals of lamproitic rocks: microthermometric data and late silicate melt evolution
No full text87Sr/86Sr Isotope Ratio as a Tool in Archaeological Investigation: Limits and Risks
No full textDuring the last forty years, the use of strontium isotopes in archaeology and biogeochemical research has spread widely. These isotopes, alone or in combination with others, can contribute to trace past and present environmental conditions. However, the interpretation of the isotopic values of strontium is not always simple and requires good knowledge of geochemistry and geology. This short paper on the use of strontium isotopes is aimed at those who use this tool (archaeologists, but not only) but who do not have a thorough knowledge of mineralogy, geology, and geochemistry necessary for a good understanding of natural processes involving these isotopes. We report basic knowledge and suggestions for the correct use of these isotopes. The isotopic characteristics of bio-assimilable strontium depend not so much on the isotopic characteristics of the bulk rock as, rather, on those of its more soluble minerals. Before studying human, animal and plant remains, the state of conservation and any conditions of isotopic pollution should be carefully checked. Samples should be collected according to random sampling rules. The data should be treated by a statistical approach. To make comparisons between different areas, it should be borne in mind that the study of current soils can be misleading since the mineralogical modification of soil over time can be very rapid
Restitic xenoliths at Cerro de Hoyazo (SE Spain): an example of crustal anatexis and melt extraction during deformation
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Oxygen Isotope Phosphoric Acid Fractionation Factor and Uncertainty on the δ18O Measurements of Calcite
No full textAt present, the isotope ratio 18O/16O (in the text expressed as δ18O) of carbonate ((Formula presented.) is usually determined by isotope ratio mass spectrometry measuring the (Formula presented.) produced dissolving the (Formula presented.) -bearing substance in concentrated (Formula presented.). As with any analytical data, the δ18O values of carbonate are also affected by uncertainty which must be considered mainly when data from different laboratories are compared. Usually, scientific papers report only repeatability and/or reproducibility of analytical results, which, have scarce significance for data comparison. With the aim of evaluating the overall uncertainty for new analytical data for low-Mg calcites, in this paper we reconsidered the δ18O data, which are reported in the literature. Two kinds of uncertainty must be taken into account: (1) that due to the calibration of the delta values using international standards (prediction uncertainty), (2) that due to small differences in the chemistry of low-Mg calcites. The two uncertainties must be added when comparing data produced in the same or different laboratories. We found that this overall uncertainty cannot be lower than about 0.2‰. Thus, uncertainty lower than 0.2‰, sometimes reported in the literature, is misleading
Geochemical features of the H2S-bearing waters of the Tabiano baths, Parma province, Italy.
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