RECENT ADVANCEMENTS IN 40AR/39AR ANALYTICAL CAPABILITIES AT THE NEVADA ISOTOPE GEOCHRONOLOGY LABORATORY

The Nevada Isotope Geochronology Laboratory (NIGL) was established in 1999 and has been providing high quality ⁴⁰Ar/³⁹Ar geochronology and thermochronology data for internal and external clientele. Recently, the NIGL purchased a new NGX-600 multicollector mass spectrometer to replace the aging MAP215-50. The NGX is equipped with nine faraday cups with ATONA® amplifiers as well as an ion counting discrete dynode electron multiplier. The instrument is equipped with a novel low temperature ion source that allows for current variation between 200 and 1000 uA. In addition, the NIGL has a new SYNRAD Firestar 30W CO₂ laser that can be used for incremental heating experiments. The lower blanks on a CO₂ laser chamber allows for higher precision geochronology results and more time efficient processing but cannot provide precise temperature values for thermochronology. The NIGL retains its temperature controlled double-vacuum furnace for thermochronology experiments. Here we present the current optimized instrument sensitivity values and reproducibility of air and mineral standards. In addition, we present new results testing the instrument’s ability to provide reliable incremental heating age determinations on a range of materials, including clinopyroxene separates, single grain groundmass analyses and trace (<2mg) amounts separates or single crystals of traditional target phases.