Radioactive dating of rock samples

Furthermore, the seven samples from the small amphibolite unit near Clear Creek, which should all be the same age because they belong to the same metamorphosed basalt lava flow, yielded K-Ar model ages ranging from 1060.4±28 Ma to 2574.2±73 Ma.

This includes two samples only 0.84 meters apart that yielded K-Ar model ages of 1205.3±.2±73 Ma.

U-Pb radioisotope dating is now the absolute dating method of first choice among geochronologists, especially using the mineral zircon.

A variety of analytical instruments have also now been developed using different micro-sampling techniques coupled with mass spectrometers, thus enabling wide usage of U-Pb radioisotope dating.

The radioisotope methods, long touted as irrefutably dating the earth's rocks as countless millions of years old, have repeatedly failed to provide reliable and meaningful absolute ages for Grand Canyon rock layers.The "age" or "date" is calculated from the amount of the daughter isotope produced by radioactive decay of the parent isotope.In Grand Canyon, the "date" of metamorphism of the basalt lavas to form these Brahma amphibolites has been determined as 1690-1710 Ma (million years ago), based on U-Pb dating of minerals in the overlying Vishnu Schist and underlying Rama Schist that formed during the metamorphism.Even when the calculated error margins are taken into account the different radioisotope dating methods yield completely different "ages" that cannot be reconciled—1240±84 Ma (Rb-Sr), 1655±40 Ma (Sm-Nd), and 1883±53 Ma (Pb-Pb) (see diagram).None of the obtained isochron "ages" corresponds to the "date" for any recognized event, neither the original lava eruptions nor the subsequent metamorphism.

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Both laboratories use standard, best-practice procedures on state-of-the-art equipment.

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