Rb sr dating

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Furthermore, magnesium-isotope anomalies within inclusions of the Allende meteorite show a linear relationship between Al is invoked.As for strontium anomalies in meteorites, straightforward uniformitarian explanations fail once again.Many new Rb-Sr age determination analyses are reported for the crystalline complex of southern Peninsular India. Data are still insufficient for a reliable geochronology. The oldest rocks have been found in Kerala, the Nilgiri Hills and southern Mysore. The age of the Dharwar System remains uncertain, although the lavas near Chitradurga give an isochron at 2345 ± 60 m.y. The Closepet Granite presents difficulties arising from its poor definition, but contains components between 24 m.y. occur in Kerala and western Tamizhagam, and could be present in Mysore, where an event at this time is recorded by biotite. have been dated, and a lower Palaeozoic event reflected in mineral ages of about 500 m.y., known to have affected all Ceylon and much of the east coast of India, has been found as far north as Coimbatore. The craton of Mysore-Hyderabad has an age of at least 2585 ± 40 m.y., which is the apparent age of the Peninsular Gneiss over a wide area.This is particularly true of the inferred stellar nucleosynthetic processes, most of which have difficulty accounting for the abundance of However, for some unknown reason, the strontium isotope anomalies are not correlated with those for magnesium.Which strontium isotopes themselves are out of balance cannot be unambiguously answered either.

It has been known for several decades that the lighter elements (notably carbon, oxygen, hydrogen and sulphur) undergo isotopic fractionation under the influence of their physical and chemical environment, and much research has been conducted to understand this behaviour.It therefore seems worthwhile to point out that isotopic fractionation does occur during the mass spectrometric ratio measurement.Strontium isotope measurements are therefore routinely corrected by measuring the (fractionated) Sr) using the appropriate mass dependence of fractionation.There is no real evidence yet of any major reflection of the Vijayan retrogressive metamorphism of Ceylon at 1140 m.y., except possibly in the intrusion of the Sivamalai soda-syenite.However, the known mineral ages of about 1690, 16 m.y.

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