Collaborative Research: Development of Improved Zircon Standards for SIMS and LA-ICP-MS U-Pb Geochronology using CA-TIMS Pre-Treatment

合作研究：使用 CA-TIMS 预处理开发改进的 SIMS 和 LA-ICP-MS U-Pb 地质年代学锆石标准品

• 批准号: 0549603
• 负责人: Jeremy Hourigan
• 金额: --
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-15 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0549603&HistoricalAwards=false
• 关键词: Collaborative; Research; Development; Improved; Zircon

Partially open system behavior is a major factor limiting accuracy in zircon U-Pb geochronology. The recently developed chemical abrasion TIMS (CA-TIMS) of Mattinson (2005) involving thermal annealing of radiation damage prior to partial dissolution experiments through a series of increasingly aggressive leaching steps shows great promise as technique for complete removal (during early dissolution steps) of high-U, Pb-loss domains within near-concordant zircon populations. Microbeam techniques such as SIMS and LA-ICP-MS rely on external standardization to well-characterized zircon for which closed system behavior has been demonstrated on the basis of multi-grain TIMS analyses. The goals of this project are twofold: 1) to test the hypothesis that aliquots of zircon characterized and cleaned-up with the CA-TIMS method function as better monitors of microbeam instrument behavior than extant untreated aliquots which are affected by minor Pb loss; 2) to produce large aliquots of treated quasi-synthetic zircon standards for distribution amongst SIMS and LA-ICP-MS labs to improve the external precision of in situ analyses of unknown samples. A suite of improved zircon standards will be distributed amongst SIMS and LA-ICP-MS labs alike representing a significant service to the geochronologic community. The project provides support for an early career geoscientist (Hourigan). Furthermore, the analytical budget provides facilities support for day-to-day operation of the UCSB Isotope Ratio Mass Spectrometry Lab which is staffed by multiple graduate students. Undergraduates will benefit through participation in analytical work.

部分开放系统行为是限制锆石 U-Pb 地质年代学准确性的主要因素。 Mattinson (2005) 最近开发的化学磨损 TIMS (CA-TIMS) 涉及在部分溶解实验之前通过一系列越来越积极的浸出步骤对辐射损伤进行热退火，显示出作为完全去除（在早期溶解步骤期间）近协调锆石群内的高 U、Pb 损失域。 SIMS 和 LA-ICP-MS 等微束技术依赖于对充分表征的锆石进行外部标准化，而锆石的封闭系统行为已在多晶粒 TIMS 分析的基础上得到了证明。该项目的目标有两个：1) 测试以下假设：与受轻微 Pb 损失影响的现有未处理等分试样相比，用 CA-TIMS 方法表征和净化的锆石等分试样可以更好地监测微束仪器的行为； 2) 生产大量经过处理的准合成锆石标准品，供 SIMS 和 LA-ICP-MS 实验室分发，以提高未知样品原位分析的外部精度。一套改进的锆石标准品将在 SIMS 和 LA-ICP-MS 实验室之间分发，这为地质年代学界提供了重要的服务。 该项目为早期职业地球科学家（Hourigan）提供支持。此外，分析预算还为 UCSB 同位素比质谱实验室的日常运营提供设施支持，该实验室由多名研究生组成。本科生将通过参与分析工作受益。