Improvement of 40Ar/39Ar age determinations for Quaternary basaltic rocks by eliminating the peak suppression effect

Abstract

Abstract Background The peak suppression effect, which suppresses the argon isotope signal due to the incomplete cleaning of gas from geological samples during measurement, is found in volatile-rich samples using the ARGUS VI noble gas mass spectrometer and its sample preparation system. Such effect hampers getting the precise isotope ratio essential for the 40Ar/39Ar age calculation. Findings The addition of one hot-getter and three room-temperature getters to the sample preparation system can effectively eliminate the peak suppression effect for several milligrams of sample during argon measurement to yield highly plausible 40Ar/39Ar ages of Quaternary volcanic rocks. Conclusions The modified preparation system makes it possible to get highly precise zero-time isotope signals, and thereby a geologically plausible 40Ar/39Ar age, especially for a small amount of volatile-rich samples.

Keywords

• 40Ar/39Ar age
• Noble gas mass spectrometer
• Quaternary
• Peak suppression
• Getters