Facility Support: Multi-User Facility for U-Th-Pb Geochronology Utilizing a Laser-Ablation Multicollector ICPMS

University Of Arizona, Tucson AZ

Investigators

Abstract

EAR-0443387 Gehrels This award supports the development and operation of a U-Th-Pb geochronology lab (the Arizona LaserChron Center) that utilizes a multicollector ICP mass spectrometer (from GV Instruments) coupled with a 193 nm excimer laser (from New Wave Research). These instruments are capable of generating U-Th-Pb ages rapidly (40 per hour), with a precision of 2-3% (2-sigma), utilizing a beam size of 10 to 50 microns. This rapid throughput is optimal for applications that require generation of large data sets (e.g., detrital zircon provenance studies). The spatial resolution provided by laser ablation also provides a powerful tool for unraveling complex growth/disturbance histories commonly encountered in igneous and metamorphic terranes. The laboratory is presently able to routinely conduct U-Th-Pb age determinations on zircon, sphene, monazite, and monazite inclusions in garnet grains, and efforts to develop analytical methods for analysis of apatite, rutile, and xenotime are ongoing. We anticipate generating ~50,000 U-Th-Pb ages per year in support of ~50 different projects. Students are encouraged to use the facility, and funds are available to support student involvement. We also encourage use of the instrument in a classroom setting as it can be operated remotely with simultaneous displays of laser excavation and age calculation.