U pb dating
In order to put the rest of the argument in context, I include here a very brief review of the background to Harris’s claims.Throughout the world, there is a sudden extinction of a large number of taxa, including the dinosaurs, at the geological boundary known as the K-T (Cretaceous – Tertiary) boundary.Zircon geochronology is a critical tool for establishing geologic ages and time scales of processes in the Earth's crust.However, for zircons compromised by open system behavior, achieving robust dates can be difficult.At the Koongarra uranium deposit, Australia, there is ample evidence of open system behaviour, or repeated migration, of U and Pb — ore textures, mineral chemistry, supergene alteration, uranium/daughter disequilibrium, and groundwater and soil geochemistry.Yet U-Th-Pb isotopic studies of the uranium ore, host rocks and soils have produced an array of false ‘isochrons’ that yield ‘ages’ which are geologically meaningless.Subsequent work has identified the Chicxulub crater as being the site of the bolide event which most closely corresponds in time to the K-T boundary (6) .by Andrew Snelling As with other radiometric ‘dating’ methods, the U-Pb and Pb-Pb isochron methods have been questioned in the open literature, because often an excellent line of best fit between ratios obtained from a set of good cogenetic samples gives a resultant ‘isochron’ and yields a derived ‘age’ that has no geological meaning.
We will see by the end of this response that there is no justification for claiming that the data supports a Young Earth.
The heavens declare the glory of God; and the firmament shows His handiwork.
Day unto day utters speech, and night unto night reveals knowledge.
Zircon from the Bishop Tuff (eastern California) was dated by the U-Pb isotope dilution thermal ionization mass spectrometry (ID-TIMS) method to evaluate time scales of magmatic evolution and applicability of the method to rocks younger than 1 Ma.
The Ar sanidine age, requiring that most zircon crystallized immediately before eruption. older indicate minimum times that a small portion of the grains resided in the magma.