Rb sr dating problems


For allegedly older samples K-Ar is used to "date" the standard and as such it still has the same problems as K-Ar dating.Oxygen isotopes may serve as a guide to evaluate whether equilibria are preserved in the Sm–Nd and/or Rb–Sr systems in eclogites that experience retrograde metamorphism.Furthermore, the same method can produce different ages on different parts of the same rock.Sometimes these are close but other times they are very different.Evidence for Isotopic Fractionation does show up in isotopic data so it is a factor that needs to be considered.Water flow through rocks is important because all parent substances and many daughter substances are water soluble.The isotopic make-up of original material is important, as is mixing of magma with surrounding material.

No meaningful isochrons are found from the Rb–Sr dating (even in the pure, primary minerals), implying that these systems were disturbed during retrograde metamorphism and the diffusion rate of Sr is faster than those of Sm–Nd and O in mafic minerals.To date rocks or other objects, scientists typically use radiometric dating.In short, the ratio of radioactive and stable isotopes in the sample are determined and the measured rate at which the isotopes decay is used as an indicator of the age of the sample.We are told that of all the radiometric dates that are measured, only a few percent are anomalous.This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points.However, it is typically unknown and simply assumed whether these ratios of elements are the result of radioactive decay over time or other processes that have taken place in the rock.

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