Automatic 40Ar/39Ar Dating Techniques Using Multicollector ARGUS VI Noble Gas Mass Spectrometer with Self-Made Peripheral Apparatus

Abstract

A new fully automatic 40Ar/39Ar laboratory with a Thermo Scientific© ARGUS VI mass spectrometer has been established in China University of Geosciences (Wuhan). We designed and developed a mini efficient preparation system (80 mL), a CO2 laser for heating samples, a crusher for extracting fluid inclusions within K-poor minerals and an air reservoir (31 L) and pipette (0.1 mL) system. The ARGUS VI mass spectrometer is operated by the Qtegra Noble Gas software, which can control the peripheral accessories, such as pneumatic valves, CO2 laser and crusher through a PeriCon (peripheral controller). The experimental procedures of atmospheric argon analyses, 40Ar/39Ar dating by laser stepwise heating and by progressive crushing in vacuo, can be fully automatically performed. The weighted mean of atmospheric 40Ar/36Ar ratios is 302.22±0.03 (1σ, MSWD=0.74, n=200), indicating that air reservoir and pipette system and the whole instrument system are very stable. This laboratory is a successful pioneer example in China to establish a new noble gas laboratory with self-made peripheral accessories expect for the mass spectrometer.