SGER: Dating Volcanic Rocks Using Syngenetic Non-Silicate Minerals

SGER：使用同源非硅酸盐矿物测定火山岩年代

• 批准号: 0841426
• 负责人: Yemane Asmerom
• 金额: $ 5.26万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0841426&HistoricalAwards=false
• 关键词: SGER; Dating; Volcanic; Rocks; Using

In this Small Grant for Exploratory Research (SGER), it is proposed to test a new geochronological technique based on U-series disequilibrium of cogenetic non-silicate minerals to date young lava flows. Previous attempts to dating lavas with U-series isotopic techniques have been problematic due to the fact that silicate crystals have variable magma residence times and, in many cases, do not have the requisite U concentration and U/Th ratios. The proposed analytical plan will be focused on the mineral gypsum. Gypsum is a common cogenetic mineral in basalts often found in lava tubes. They have the required high U and low Th concentrations. Preliminary data on gypsum crystals give encouraging but mixed results. The ultimate purpose of this SGER will be to develop a set of criteria to distinguish datable materials from those that are not by using strontium, sulfur and in some cases radium isotopic data in a suitable field area. These will be used eventually to document and establish the likelihood that this new technique is feasible for a number of different rock types. If successful, results from this project will have broad applicability in the Earth Sciences.

在这个探索性研究（SGER）的小补助金，它建议测试一个新的地质年代学技术的基础上的U系列不平衡的同生非硅酸盐矿物的年轻熔岩流的日期。以前尝试用U系列同位素技术测定熔岩的年代是有问题的，因为硅酸盐晶体具有可变的岩浆停留时间，并且在许多情况下，没有必要的U浓度和U/Th比。拟定的分析计划将侧重于矿物石膏。石膏是玄武岩中常见的同生矿物，常在熔岩管中发现。 它们具有所需的高U和低Th浓度。关于石膏晶体的初步数据给出了令人鼓舞但喜忧参半的结果。 该SGER的最终目的将是制定一套标准，通过在适当的野外区域使用锶、硫和某些情况下镭同位素数据，区分可定年的材料和不可定年的材料。 这些最终将用于记录和建立这种新技术对许多不同岩石类型可行的可能性。 如果成功，该项目的成果将在地球科学中具有广泛的适用性。