Improving Consistency in Laser Ablation Geochronology; Workshop on Data Handling in LA-ICP-MS U-Th-Pb Geochronology; San Francisco, California, 12–13 December 2009



The use of uranium-thorium-lead (U-Th-Pb) laser ablation—inductively coupled plasma mass spectrometry (LA-ICP-MS) geochronology involves rapid analysis of U- and Th-rich accessory minerals. It routinely achieves 1–2% precision for U-Th-Pb dates constituting detrital mineral age spectra and for dating igneous and metamorphic events. The speed and low setup and analysis cost of LA-ICP-MS U-Th-Pb geochronology has led to a proliferation of active laboratories. Tens of thousands of analyses are produced per month, but there is little agreement on how to transform these data into accurate U-Th-Pb dates. Recent interlaboratory blind comparisons of zircon samples indicate that resolvable biases exist among laboratories and the sources of bias are not fully understood. Common protocols of data reduction and reporting are essential for scientists to be able to compare and interpret these data accurately.

Members of the international community met prior to the 2009 AGU Fall Meeting in San Francisco to address these issues. Funded by the U.S. National Science Foundation (NSF), this collaboration between the Working Group on LA-ICP-MS U-Th-Pb Geochronology of the International Association of Geoanalysts (IAG) and the EARTHTIME and EarthChem communities was attended by 34 scientists from nine countries and multiple geochronological specialties. Attendees sought to compare and contrast the wide array of data reduction software currently used, agree on a common data reduction strategy and reporting protocol, and discuss funding agency-driven initiatives to create community databases for the wealth of data produced.