Rb sr dating validating my windows xp

The possibility of isotopic fractionation as an explanation for differences in Sr has been proposed to both authors on many occasions.It therefore seems worthwhile to point out that isotopic fractionation does occur during the mass spectrometric ratio measurement. When diffusive isotope fractionation of Sr isotopes is repeated a sufficient number of times by within-mantle processes on isotopically-anomalous mantle xenoliths (each of which originally had low Sr ratios.When mixed with variable amounts of terrestrial nonradiogenic strontium, these remnants generate mixing lines indistinguishable from age-indicative Rb-Sr isochrons.When we produced the formula for K-Ar dating, it was reasonable enough to think that there was little to no argon present in the original state of the rock, because argon is an inert gas, does not take part in chemical processes, and so in particular does not take part in mineral formation.Strontium, on the other hand, does take part in chemical reactions, and can substitute chemically for such elements as calcium, which is commonly found in igneous rocks.

So how can Rb-Sr ‘isochrons’ be explained in the context of a young Earth?In the reasoning that follows, the reader may recognize a sort of family resemblance to the reasoning behind step heating in the Ar-Ar method, although the two are not exactly alike. When an igneous rock is first formed, its minerals will contain varying concentrations of rubidium and strontium, with some minerals being high in rubidium and low in strontium, others being high in strontium and low in rubidium.We can expect these differences to be quite pronounced, because rubidium and strontium have different chemical affinities: as we have noted, rubidium substitutes for potassium, and strontium for calcium.If Rb-Sr ‘isochrons’ are actually the result of mixing lines, the collinear relationship between different isotopic compositions to begin with.In proper usage, the phrase ‘isotope fractionation’ refers exclusively to the physical separation of one isotope of an element from another isotope of the same element.

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