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

请国家环境研究中心提供资金，用于在不列颠哥伦比亚大学太平洋同位素和地球化学研究中心购买对地质材料进行单颗粒同位素稀释铀铅定年研究所必需的设备。单颗粒和部分颗粒测年的能力可能是过去10年来在高精度U-Pb地质年代学领域取得的最重要的进步，并允许前所未有的时间尺度分辨率和对造山、矿化和岩浆过程的洞察。该设备包括（1）PicoTrace级联两级冲天炉式亚沸系统，配有专用热板和高精度温度控制器，能够生产每24小时高达500 mL的超纯试剂，微量金属浓度低于万亿分之一，以及（2）Mettler超微量天平，能够准确精确地测量低微克单粒样品的质量。低铅空白（小于万亿分之一克）是成功进行单颗粒（如锆石和其他副相）铀铅同位素定年研究的绝对要求，超纯试剂对实现这些低铅空白至关重要。亚沸腾装置的封闭系统设计确保了产品的一致纯度和体积，并且重要的是，与目前使用的其它亚沸腾器设计相比，提供了额外的安全措施。该微量天平可快速测定极小样品的质量，非常适合在受控环境中使用，如洁净实验室，具有免手动开门功能和自动校准功能，包括校正温度变化和轻微振动的功能。亚沸系统和微量天平将直接服务于UBC大量不同的高素质人员的需求，以及来自其他加拿大，美国和国际大学的访问研究人员，无论是今天还是未来20-25年（所需设备的预期寿命）。

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).