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The ideal scenario according to Bowen's reaction series would see a granite melt begin crystallizing a cumulate assemblage of plagioclase and hornblende (i.e.; tonalite or diorite), which is low in K (and hence Rb) but high in Sr (as this substitutes for Ca), which proportionally enriches the melt in K and Rb.

This then causes orthoclase and biotite, both K rich minerals into which Rb can substitute, to precipitate.

Rb-Sr ages of glauconite pellets commonly fall short of the presumed age of deposition by 10-20%, according to current estimates of the geologic time scale.

Rb dating site

Consequently, in pellets where tightly bound, nonexchangeable Rb and Sr have remained a closed chemical system since deposition, removal of the exchangeable cations with ammonium acetate (NH OAc) can raise the apparent age to coincide with the expected depositional age.

In other cases the age of pelletal glauconite remains younger than the depositional age after chemical treatment.

Whole rocks define an isochron of age 4.486±0.020 Ga .

This is in agreement with the results for H- and E-type chondrites.

Analyses for chondrules from Soko Banja yield a very good isochron of age 4.452±0.020 Ga and strontium initial ratio 0.69954±0.00024, and give an interval for metamorphism of (37±10)×10Sr system is also disturbed in Guidder and Ensisheim, probably as a consequence of shock.

These results are discussed in comparison with our former studies, and in relation with thermal metamorphism in the LL chondrite parent body(ies).

The resulting Rb-Sr ratios and Rb and Sr abundances of both the whole rocks and their component minerals will be markedly different.

This, thus, allows a different rate of radiogenic Sr to evolve in the separate rocks and their component minerals as time progresses.

Direct mineral dating is critical for thorough understanding of the genesis of hydrothermal mineralizations, ore forming processes and events of fracturing and related fluid-rock interaction.

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