Oxygen and Hydrogen Isotope Studies of Igneous Rocks and Associated Hydrothermal Alteration

火成岩及相关热液蚀变的氧和氢同位素研究

• 批准号: 0106696
• 负责人: Hugh Taylor
• 金额: $ 10.53万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106696&HistoricalAwards=false
• 关键词: Oxygen; Hydrogen; Isotope; Studies; Igneous

TaylorEAR-0106696We are attempting to show that equilibrium iron-isotope fractionations among simple iron-bearing complexes and Fe metal can be accurately calculated using a combination of force-field modeling together with available measurements of vibrational frequencies from infrared and Raman spectroscopy. This is important because of its pertinence in interpreting the exciting new results by other workers of high-precision iron isotope measurements on natural materials and between species in aqueous solution and those bound to ion-exchange resins. We are also finishing up an oxygen and radiogenic isotope study of granitic plutons in Nevada and Utah for which preliminary results have shown a systematic involvement of different source rocks during each of three stages of magmatism in the Jurassic, Cretaceous, and Cenozoic. A third goal is to complete our understanding of the remarkable oxygen isotope patterns in phenocrysts and groundmass found in the upper parts of welded ash-flow tuffs, exemplified in our studies of the Bishop Tuff (Holt and Taylor, 1998), where we showed that the low-18O zones exhibited a one-to-one correspondence with mapped fossil fumarolic structures exposed in the uppermost 70-80 meters of the tuff We are in the process of examining the exposed upper 15 meters of the 1912 ash-flow sheet in the Valley of Ten Thousand Smokes (VTTS), Alaska (where the fumaroles are known from direct observation to have terminated about 15 years after eruption), thereby linking the scientific observations made on recently active fumaroles in the VTTS with the fossil fumaroles in the Bishop Tuff.

我们试图证明，简单的含铁络合物和Fe金属之间的平衡铁同位素分馏可以使用力场模型与红外和拉曼光谱的振动频率的可用测量相结合来精确计算。 这是重要的，因为它的相关性在解释令人兴奋的新结果，由其他工作者的高精度铁同位素测量的天然材料和物种之间的水溶液和那些绑定到离子交换树脂。我们还完成了对内华达州和犹他州花岗岩体的氧和放射性同位素研究，初步结果表明，在侏罗纪、白垩纪和新生代三个岩浆活动阶段中，不同的源岩都有系统的参与。 第三个目标是完成我们对在熔结灰流凝灰岩上部发现的斑晶和基质中的显著氧同位素模式的理解，在我们对主教凝灰岩的研究（Holt和Taylor，1998年）中举例说明了这一点，我们在研究中表明，低18 O区与凝灰岩最高70-80米处暴露的映射化石火山结构呈现出一一对应的关系 我们正在研究阿拉斯加州万烟谷（VTTS）1912年火山灰流面暴露的上部15米（直接观察发现火山灰在喷发后约15年终止），从而将对VTTS中最近活跃的火山灰的科学观察与主教凝灰岩中的化石火山灰联系起来。