Collaborative Research: Improving the Accuracy and Precision of Monazite and Allanite Geochronology via ID Th-Pb Ages for Reference Materials

合作研究：通过参考材料的 ID Th-Pb 年龄提高独居石和铜铜矿年代学的准确度和精度

• 批准号: 1050043
• 负责人: John Cottle
• 金额: $ 13.33万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2014-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1050043&HistoricalAwards=false
• 关键词: Collaborative; Research; Improving; Accuracy; Precision

Collaborative Research: Improving the accuracy and precision ofmonazite and allanite geochronology via ID Th-Pb ages for referencematerialsThe principal limitation for obtaining high-precision, accurate standard-based 208Pb/232Th ages from monazite and allanite is the lack of appropriate, well-characterized reference materials. Because both monazite and allanite are compositionally variable and SIMS, LA-ICP-MS incur instrumental mass-dependent fractionation, it is essential to closely match standards with unknowns. This proposal seeks to determine isotope dilution (ID) Th-Pb ages for the Th-rich accessory minerals monazite and allanite. Th-Pb ages currently exist for only one reference material that is commonly used-'554'. Consequently, all standard-based geochronologic measurements require an assumption that Th-Pb and U-Pb ages are equivalent. This assumption is unnecessary and, in many cases, invalid. By obtaining high-precision ID Th-Pb ages for a suite of well-characterized, community-wide reference materials, this research will provide a means of independently calibrating Th-Pb ages for minerals that can be linked to fundamental tectonic processes.Intellectual Merito Eliminates the need to assume concordance among the three decay systems (235U, 238Uand 232Th decay chains) by providing independently verified U-Pb and Th-Pb ages.o Improves precision on age measurements for a chronometer that can be directly linkedto the metamorphic and magmatic history of a terraneo Provides well-characterized standards to the community for high-precision, standardbasedgeochronology.Broader impacts1. This proposed research seeks to address the fundamental aim of the EARTHTIME initiative: "the development of the geochronological techniques necessary to produce temporal constraints with uncertainties approaching 0.1 % of the radioisotopic ages."o A website will be developed that contains the information about the reference materials and the methods for measuring the ID TIMS and ICP-MS ages. This information will be linked to the EARTHTIME website.o An educational module will be developed that can be integrated into the EARTHTIME mission for educating students about understanding geologic time. This module will demonstrate linking pressure, temperature and time histories.2. This project supports two early career scientists-John Cottle (UCSB faculty) and Emily Peterman (Stanford Postdoctoral Fellow). In addition, Peterman is a young female scientist (Ph.D. 2009).3. This study will train undergraduates (UCSB) in laboratory investigations and provide a component of graduate research for graduate students at UCSB and Stanford.4. The results of the proposed research will impact the geochronology community at large:o Thermal Ionization Mass Spectrometryo Secondary Ionization Mass Spectrometryo Electron Probe MicroAnalysiso (Laser Ablation) Inductively Coupled Plasma Mass Spectrometry

协作研究：通过ID TH-PB年龄提高了Monazite和Allanite的准确性和精确度，以进行参考材料，以获得高精度，准确的基于标准的基于标准的208pb/232年龄的主要限制，这是缺乏适当的，良好的特定的特色参考材料。由于独居石和阿兰力岩都是组成的可变和SIMS，因此LA-ICP-MS产生仪器质量依赖性分级，因此与未知数紧密匹配标准是必不可少的。该提案旨在确定富含TH的辅助矿物质矿物质和Allanite的同位素稀释（ID）TH-PB年龄。 TH-PB年龄目前仅适用于通常使用的一种参考材料。因此，所有基于标准的测量测量结果都需要假设TH-PB和U-PB年龄是等效的。这个假设是不必要的，在许多情况下，这是无效的。通过获得一套特征良好的社区范围的参考材料的高精度ID TH-PB年龄，这项研究将提供一种可以独立校准的矿物质的手段，这些矿物可以与基本的构造过程相关联。IntlectualMerito需要在三个decay decay Systems（2355U，2352222年）中进行一致的一致性（ Th-PB年龄。这项拟议的研究旨在解决Earthtime计划的基本目的：“生产时间限制所需的地年学技术的发展，不确定性接近0.1％的放射性病年龄。这些信息将链接到Earthtime网站。该模块将展示链接压力，温度和时间历史。2。该项目支持两个早期的职业科学家 - 约翰·科特尔（UCSB教职员工）和艾米莉·彼得曼（Emily Peterman）（斯坦福大学博士后研究员）。此外，彼得曼（Peterman）是一位年轻的女科学家（2009年博士）.3。这项研究将在实验室研究中培训本科生（UCSB），并为UCSB和Stanford.4的研究生提供研究生研究的组成部分。4。拟议的研究的结果将影响总体：o热电离质谱次级电离质谱质谱质谱质谱探针探针微分析（激光烧蚀）电感耦合等离子体质谱法