Sub-boiling system and microbalance for single grain U-Pb geochronology

点击翻译按钮获取中文摘要

Funds are requested from NSERC for the purchase of equipment that is essential for single-grain isotope dilution uranium-lead dating studies of geological materials at the Pacific Centre for Isotopic and Geochemical Research at UBC. The capability of dating single grains and parts of grains is probably the single most important advancement to have occurred in the field of high-precision U-Pb geochronology within the last 10 years, and allows for unprecedented timescale resolution and insight into orogenic, mineralization, and magmatic processes. The equipment includes (1) a PicoTrace cascading two-stage cupola-type sub-boiling system with dedicated hot plate and high-precision temperature controller, capable of producing up to 500 mL per 24 hours of ultra-pure reagents with trace metal concentrations of less than one part per trillion, and (2) a Mettler ultra-microbalance that can accurately and precisely measure the mass of low-microgram single grain samples. Low-lead blanks (less than one trillionth of a gram) are an absolute requirement to successfully carry out single grain (e.g. zircon and other accessory phases) uranium-lead isotopic dating studies and ultra-pure reagents are essential to achieving these low blanks. The closed-system design of the sub-boiling apparatus assures consistent purity and volume of product, and importantly affords an additional measure of safety compared to other sub-boiler designs currently in use. The microbalance will allow for rapid mass determinations of extremely small samples and is ideally suited to use in controlled environments such as clean laboratories, with a hand-free door opening capability and automatic calibration functions including those that correct for variations in temperature and slight vibrations. The sub-boiling system and microbalance will directly serve the needs of a large and diverse group of highly-qualified personnel at UBC, plus visiting researchers from other Canadian, U.S. and international universities, both today and during the next 20-25 years (the expected lifetime of the requested equipment).