Two Carboniferous ages

Abstract

Using replicate measurements of a homogeneous reference zircon, the discrimination of Pb+ and UO- ions relative to U+ observed in zircon analysis with the SHRIMP ion microprobe has been established as a power law relationship. This relationship minimizes uncertainty in comparative measurement of 206Pb/238U ages in zircons. Ages thus obtained have been compared with isotope dilution thermal ionisation mass spectrometric (IDTIMS) analysis of zircons in the Paterson Volcanics (Carboniferous, Australia) and 40Ar/39Ar dating of sanidines in the Z1 tonstein (Carboniferous, Germany). No bias can be detected between the three dating methods, confirming that SHRIMP zircon 206Pb/238U ages are accurate and comparable with other well-measured Phanerozoic ages. -from Authors Show more