HR: 1340h
AN: V23B-1436    [Abstracts]
TI: Multicollector 40Ar/39Ar Dating: Protocols, Reproducibility and Intercalibration of Mineral Standards
AU: * Storey, M
EM: storey@ruc.dk
AF: QUADLAB, Department of Environmental, Social and Spatial Change, Roskilde University, Universitetsvej 1, PO Box 260, Roskilde, DK-4000, Denmark
AU: Deino, A L
EM: adeino@bgc.org
AF: Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, United States
AU: Stecher, O
EM: ostecher@ruc.dk
AF: QUADLAB, Department of Environmental, Social and Spatial Change, Roskilde University, Universitetsvej 1, PO Box 260, Roskilde, DK-4000, Denmark
AB: The recent availability of commercial multi-collector noble gas mass spectrometers provides new opportunities for improved precision in 40Ar/39Ar dating, particularly for young Quaternary aged samples, where precise measurement of the 40Ar/36Ar ratio is critical. Multicollection reduces the errors introduced through signal decay and sequential measurement of different isotopes species on a single collector instrument. QUADLAB is equipped with a NU-Instruments multicollector Noblesse noble gas mass spectrometer, which is configured with a faraday detector and three ion-counting electron multipliers. The instrument has the capability to measure several noble gas isotopes simultaneously and to change measurement configurations instantaneously by the use of QUAD lenses (zoom optics). The mass spectrometer, laser and extraction line are fully automated using a modified version of the program "MASS SPEC". Detector intercalibration, deadtime determination, instrument mass fractionation and long-term data reproducibility are evaluated by repeated measurement of air aliquots from a calibrated air pipette. We present analytical protocols for the measurement of irradiated samples and results of intercalibration of different monitor minerals.
UR: http://www.quadlab.dk
DE: 1100 GEOCHRONOLOGY
DE: 1105 Quaternary geochronology
DE: 1115 Radioisotope geochronology
DE: 1194 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting