RII Track-4: Why are Young Volcanic Rocks Undateable: Chemistry, Environment, or Instrumentation?

地质年代学是一门利用岩石和其他矿物形成时所含的微量放射性同位素来确定地球物质年龄的科学。不同的放射性测年方法适用于不同的材料，其准确度在时间尺度上也各不相同。该奖学金使阿拉斯加费尔班克斯大学的一名早期职业研究员和一名研究生实习生能够与俄勒冈州立大学的研究人员合作。在那里，他们将使用最先进的设备来确定来自阿拉斯加阿留申和弗兰格尔弧的年轻火山岩的年龄。年轻火山岩的精确地质定年对于了解阿拉斯加火山的喷发历史、火山和地震危险性评估以及构造重建具有重要意义。该项目将调查样品的化学成分和环境以及现有测量仪器的灵敏度和精度如何影响确定年轻火山岩年龄的不确定性。这项研究将有助于开发新的方法来准确地确定年轻火山岩的年代，并提高他所在机构的PI的研究能力。通过这个项目积累的培训和合作将丰富参与的教师和学生的职业生涯。该合同将允许阿拉斯加费尔班克斯大学的研究人员与俄勒冈州立大学氩地质年代学实验室（OSU-AGL）合作，生产高精度的40Ar/39Ar地质年代学数据，以确定阿拉斯加火山岩和产物的年龄。阿留申弧线和弗兰格尔弧线由于样品中的放射化学、可用仪器的限制以及岩浆室的质量分馏过程所产生的不确定性，阻碍了这些年轻火山岩的准确测年。该项目通过使用稀有气体多收集器质谱仪和OSU-AGL提供的软件对火山岩进行系统实验，克服了其中的一些困难。研究人员将从广泛的构造-岩浆环境中选择样本，例如，单源锥、板内岩浆作用、弧转化岩浆作用和弧岩浆作用，以研究潜在的质量分馏影响。PI和他的研究生将通过在单个探测器上跳峰来使用稀有气体质谱仪来扩展他们的专业知识，并将接受现代仪器操作方面的培训，从而有可能提高他们所在机构的研究仪器和能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Description Geochronology is the field of science that determines the age of earth materials using trace radioisotopes contained in rocks and other minerals when they were formed. Different methods used for radiometric dating apply to different materials and vary in the timescales over which they are accurate. This fellowship enables an early career researcher at the University of Alaska Fairbanks and a graduate student trainee to collaborate with researchers at the Oregon State University. While there they will use state-of-the art equipment to determine the age of young volcanic rocks from Alaska's Aleutian and Wrangell arcs. Precise geological dating of young volcanic rocks is important in understanding the eruptive history of volcanoes in Alaska, volcanic and seismic hazards assessment, and tectonic reconstructions. The project will investigate how the chemistry and environments of the samples and the sensitivity and precision of available measurement instrumentation contribute to the uncertainties in determining the age of young volcanic rocks. The research will enable the development of new methods to accurately date young volcanic rocks and lead to improved research capabilities for the PI at his home institution. The training and collaborations accrued through this project will enrich the careers of the participating faculty and students. Technical Description This award will allow researchers at the University of Alaska-Fairbanks to collaborate with the Oregon State University Argon Geochronology Laboratory (OSU-AGL) to produce high-precision 40Ar/39Ar geochronology data to determine the age of volcanic rocks and products from Alaska?s Aleutian and Wrangell arcs. Accurate dating of these young volcanic rocks is hampered by uncertainties arising from radiochemistry within the samples, limitations on the available instrumentation, and mass fractionation processes in the magma chamber. This project overcomes some of these difficulties through systematic experimentation of the volcanic rocks using the noble gas multi-collector mass spectrometer and software available at the OSU-AGL. The researchers will select samples from a broad range of tectonic-magmatic settings, for example, monogenic cones, intraplate, arc-transform magmatism, and arc magmatism, to investigate potential mass fractionation influences. The PI and his graduate student will extend their expertise with the use of a noble gas mass spectrometer by peak-hopping on a single detector and will be trained in the operation of modern instrumentation with the potential to enhance the research instrumentation and capabilities at their home institution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.