Pb isotopes ratios

The Pb isotope ratios are consistent with young mineralisation (less than 800 My), Neo-Proterozoic to Palaeozoic and are similar to lead isotope ratios of epigenetic mineralisation. This suggests a radiogenic lead contribution from the upper crust. The isotopic curves generated by the plumbo-tectonic model of Zartman and Doe (1980) show that the isotopic ratios are below 800 Ma and correspond to crustal values. 

Sandstone around the uranium deposits typically has radiogenic ° PbF° Pb isotope ratios (>30) (Fig. 5), with Pb isotopic compositions that are unsupported by the amount of U in the sandstone. This is consistent with the introduction of this Pb... 

Year Three Complete analysis of trace elements by ICP-MS at Lawrence University analysis of major elements by XRF at Macalester College (up to 100 samples) determination of Sr, Nd, and Pb isotopic ratios of a selection of Wolf and Darwin samples by TIMS at Cornell (up to 30 samples). Interpretation of geochemical data, modeling of melting parameters. Presentation of results at Fall AGU meeting by undergraduate student(s). Preparation for fieldwork. 

Equation 5-61 involves only Pb isotopic ratios and is called the Pb-Pb isochron. There are a few advantages of this Pb-Pb isochron compared to the individual U-Pb isochrons. One is that Pb isotopic ratios can be measured more accurately than U/Pb ratios. Hence, the above equation has the advantage of Ar-Ar method compared to the K-Ar method. Secondly, if there was recent (such as yesterday or in the last million years) U loss or gain or Pb loss, the loss or gain would not affect the Pb isotopic composition and hence would not affect Pb-Pb dating (but it would affect U-Pb isochrons). Pb gain would affect the Pb-Pb isochron. 

Figure 2. Comparison of TIMS and time of flight ICP-MS Pb isotope ratios from...

Sr, Nd and Pb isotopic ratios of mafic rocks (Fig. 1.7) show large and continuous variations. However, various regions exhibit rather restricted and distinct isotopic signatures (Conticelli et al. 2002 and references therein). Oxygen isotopic data are also variable in the volcanic rocks from central-southern Italy. Data on whole rocks have brought to the conclusion... 

Radiogenic isotope data have added important information on evolution of mantle sources. The continuous trends of Sr-Nd-Pb isotope ratios along the Italian peninsula, from Etna-Iblei to Tuscany, have been interpreted as a result of contamination of upper mantle by different types of upper... 

Mafic rocks from the Sicily Province display variable abundances of incompatible elements, which increase from tholeiites to alkali basalts and nephelinites. However, all the rocks show low LILE/HFSE ratios, typical of intraplate basalts, in contrast with the high LILE/HFSE compositions of volcanism from the Aeolian arc and the Italian peninsula. They have a relatively restricted range of Sr-Nd isotopic compositions, but variable Pb isotopic ratios, which fall along a trend connecting HIMU and intermediate compositions between DMM and EMI mantle. 

ICP-MS analysis of human tissue [245] has been described in several reports. Microwave digestion was commonly used for sample preparation. Analysis of tissues can provide information on essential elements as well as toxic elements. Pb isotope ratios depend on the source of lead. Therefore, ICP-MS isotopic... 

ICP-MS is widely used to assess drinking water quality. Environmental Protection Agency (EPA) methods 200.8 and 1638 for the analysis of drinking and waste waters use ICP-MS [307-309]. Sources of Pb in drinking water can be assessed from Pb isotope ratios. In one study, Pb/ Pb, Pb/ Pb, Pb/ Pb isotope ratios in tap water were compared to those of plumbing materials [310]. The authors were able to conclude that the copper pipe and solder were the main sources of Pb. 

ICP-MS isotope ratio measurements of house dust samples were used to assess potential sources of Pb [342]. Street dust and soil outside the house showed similar Pb isotope ratios, but lead paint in the house had a different isotopic pattern. Sources of lead outside the home were found to contribute as much to lead in most of the house dusts as did lead from lead-based paints inside the house. 

Semlali, R. M., Van Oort, F., Denaix, L., and Loubet, M. (2001). Estimating distributions of endogenous and exogenous Pb in soils by using Pb isotopic ratios. Environ. Sci. Technol. 35, 4180-4188. 

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