CHIME monazite dating: Pb analysis on an R_R = 100 mm spectrometer and correction of interferences between Th, U, and Pb with natural monazite

Abstract

This paper outlines an advanced procedure involving the chemical Th-U-total Pb isochron method (CHIME) dating of monazite using a field-emission electron probe microanalyzer (FE-EPMA) equipped with spectrometers of 100 mm Rowland circle (R R ) radius. The higher count rate of R R = 100 mm wavelength dispersive spectrometer (WDS) compared to R R = 140 mm WDS enables measurements to be taken in a shorter time. CHIME dating using R R = 100 mm WDS had previously been difficult because of lower resolution compared to that of R R = 140 mm WDS. This problem has been overcome by a new interference correction method using natural monazites.