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05-Dec-2019 12:41# #
Thus, assigning age significance to a result requires studying the metasomatic and thermal history of the rock, any metamorphic events, and any evidence of fluid movement.
Therefore, given sufficient time for significant production (ingrowth) of radiogenic For example, consider the case of an igneous rock such as a granite that contains several major Sr-bearing minerals including plagioclase feldspar, K-feldspar, hornblende, biotite, and muscovite.
Each of these minerals has a different initial rubidium/strontium ratio dependent on their potassium content, the concentration of Rb and K in the melt and the temperature at which the minerals formed.
A Rb-Sr date which is at variance with other geochronometers may not be useless, it may be providing data on an event which is not representing the age of formation of the rock.
The Rb-Sr dating method has been used extensively in dating terrestrial and lunar rocks, and meteorites.
This then causes orthoclase and biotite, both K rich minerals into which Rb can substitute, to precipitate.