An isotope fractionation mechanism for the nonradiogenic origin of excess strontium-87 by John Woodmorappe Summary This new model for 87Sr accumulation eliminates the need for either long-term decay of 87Rb, or the acceleration of 87Rb decay by many orders of magnitude. When mixed with variable amounts of terrestrial nonradiogenic strontium, these remnants generate mixing lines indistinguishable from age-indicative Rb-Sr isochrons. Although the unreliability of the Rb-Sr method for dating is readily demonstrated, 1 , 2 it is important that alternative models are developed to explain the observed patterns of strontium isotopes. The ratios of 88Sr, 86Sr, and 84Sr, relative to each other, are commonly believed to be invariant throughout Earth materials. However, the ratio of 87Sr relative to the other Sr isotopes varies widely. [PUNIQGOOGLESNIPMIX-1
Dating - Rubidium—strontium method Britannica. Because rubidium is concentrated in crustal rocks, the continents have a much higher abundance of the... Rubidium dating - toysthatteachbothell. The rubidium-strontium dating method is often used in geologic studies.
radiometric dating explained
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