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Rb sr dating ppt airport, presentation on theme: "rb-sr and sm-nd dating 8/30/12"— presentation transcript:

Rb-Sr can then be used on the altered mineralogy to date the time of this alteration, but not the date at which the rock formed. This of course assumes that the Pb in the galenas was also derived predominantly from uranium decay. This, thus, allows a different rate of radiogenic Sr to evolve in the separate rocks and their component minerals as time progresses.

This is well known for the Cenozoic time-scale but, due to poorer preservation of carbonate sequences in the Mesozoic and earlier, it is not completely understood for older sequences. The application of Sr isotope stratigraphy is generally limited to carbonate samples for which the Sr seawater curve is well defined.

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.

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Isotopes in the Earth Sciences. The application of Sr isotope stratigraphy is generally limited to carbonate samples for which the Sr seawater curve is well defined. Total precipitation shows areas of active precipitation on the map, refreshed 12 times a day.

By using this site, you agree to the and. Instead, they contended that the scatter of points could be contained between two lines radiating from the diagram's origin, lines that essentially represented isochrons for uraninites and galenas from the Ranger and Nabarlek uranium deposits in the same geological region.

Several preconditions must be satisfied before a Rb-Sr date can be considered as representing the time of emplacement or formation of a rock.

There is truly something for everyone! The slope of the line dictates the age of the sample. Concurrently, the crust will become enriched in Rb relative to Sr. Calculating the age[ edit ] The age of a sample is determined by analysing several minerals within the sample. The ideal scenario according to would see a granite melt begin crystallizing a assemblage of plagioclase and hornblende i.