Rb sr method of dating
A figure expressible in billions of years is ideal.
In the Rb-Sr method, we used Sr, and it will be equally valid.
Source of text: This review was assembled by Dan Snyder from the references below.
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The reader who has not read the article on the Rb-Sr method will find this present article almost completely incomprehensible, and should go back and read it. During fractional crystallization, Sr tends to be come concentrated in plagioclase, leaving Rb in the liquid phase.Hence, the Rb/Sr ratio in residual magma may increase over time, resulting in rocks with increasing Rb/Sr ratios with increasing differentiation. If the initial amount of Sr is known or can be extrapolated, the age can be determined by measurement of the Rb and Sr concentrations and the Sr ratio.The walls of the canyon are mostly cut into horizontal rock layers of Paleozoic age (green in Figure 1, above).
There is an angular unconformity at the bottom of the Paleozoic layers.
The table below shows some sets of three isotopes which can be treated like rubidium and strontium for the purposes of dating; the table also shows the half-life of the parent and its decay mode.