TY - JOUR
T1 - U-Pb zircon in situ dating with LA-MC-ICP-MS using a mixed detector configuration
AU - Chemale, Farid
AU - Kawashita, Koji
AU - Dussin, Ivo A.
AU - Ávila, Janaína N.
AU - Justino, Dayvisson
AU - Bertotti, Anelise
PY - 2012/6
Y1 - 2012/6
N2 - The LA-MC-ICP-MS method applied to U-Pb in situ dating is still rapidly evolving due to improvements in both lasers and ICP-MS. To test the validity and reproducibility of the method, 5 different zircon samples, including the standard Temora-2, ranging in age between 2.2 Ga and 246 Ma, were dated using both LAMC- ICP-MS and SHRIMP. The selected zircons were dated by SHRIMP and, after gentle polishing, the laser spot was driven to the same site or on the same zircon phase with a 213 nm laser microprobe coupled to a multi-collector mixed system. The data were collected with a routine spot size of 25 μm and, in some cases, of 15 and 40 μm. A careful cross-calibration using a diluted U-Th-Pb solution to calculate the Faraday reading to counting rate conversion factors and the highly suitable GJ-1 standard zircon for external calibrations were of paramount importance for obtaining reliable results. All age results were concordant within the experimental errors. The assigned age errors using the LA-MC-ICP-MS technique were, in most cases, higher than those obtained by SHRIMP, but if we are not faced with a high resolution stratigraphy, the laser technique has certain advantages.
AB - The LA-MC-ICP-MS method applied to U-Pb in situ dating is still rapidly evolving due to improvements in both lasers and ICP-MS. To test the validity and reproducibility of the method, 5 different zircon samples, including the standard Temora-2, ranging in age between 2.2 Ga and 246 Ma, were dated using both LAMC- ICP-MS and SHRIMP. The selected zircons were dated by SHRIMP and, after gentle polishing, the laser spot was driven to the same site or on the same zircon phase with a 213 nm laser microprobe coupled to a multi-collector mixed system. The data were collected with a routine spot size of 25 μm and, in some cases, of 15 and 40 μm. A careful cross-calibration using a diluted U-Th-Pb solution to calculate the Faraday reading to counting rate conversion factors and the highly suitable GJ-1 standard zircon for external calibrations were of paramount importance for obtaining reliable results. All age results were concordant within the experimental errors. The assigned age errors using the LA-MC-ICP-MS technique were, in most cases, higher than those obtained by SHRIMP, but if we are not faced with a high resolution stratigraphy, the laser technique has certain advantages.
KW - Faraday cups
KW - MC-ICP-MS
KW - Multi-ion counting system
KW - SHRIMP
KW - U-Pb in situ zircon dating
UR - http://www.scopus.com/inward/record.url?scp=84875616193&partnerID=8YFLogxK
U2 - 10.1590/S0001-37652012005000032
DO - 10.1590/S0001-37652012005000032
M3 - Article
SN - 0001-3765
VL - 84
SP - 275
EP - 295
JO - Anais da Academia Brasileira de Ciencias
JF - Anais da Academia Brasileira de Ciencias
IS - 2
ER -