Continental crust neodymium/strontium

The fractionated igneous and sedimentary rocks in Figure 20 have Rb/Sr and Eu/Sr ratios that are much higher than those in current estimates for the upper continental crust. The latter can be constrained by the strontium isotope ratios of continental run-off (—0.712), and its model neodymium age (—1.8 Ga). According to this method, a minimum time-integrated upper crustal Rb/Sr ratio of 0.14 is indicated. 

Sr/ Sr = 0.70450. The isotope ratios of strontium and neodymium in igneous, metamorphic, and sedimentary rocks of the continental crust form points in... 

The beta decay scheme of rhenium-187 to osmium-187 maybe applied to the study of sulfide minerals of molybdenum and osmium-rich minerals such as iridosmine. Together with rubidium/strontium, samarium/neodymium, lutetium/hafnium, and uranium/lead methods, it has been used to examine mantle differentiation and the accretion of continental crust. In molybdenites, rhenium concentrations vary from a few ppm to as much as 1.88%. The element has two naturally occurring isotopes, and these are the stable rhenium-185 with a relative abundance of 37.398% and the radioactive rhenium-187 with a relative abundance of62.602%. This decays as follows ... 

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