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: 9317036
• 负责人: Hugh Taylor
• 金额: $ 52.53万
• 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: 1994
• 资助国家: 美国
• 起止时间: 1994-01-15 至 1997-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9317036&HistoricalAwards=false
• 关键词: Oxygen; Hydrogen; Isotope; Studies; Igneous

9317036 Taylor Low-18O hotspots like Hawaii may represent recycled low-18O oceanic crust. This hypothesis will be tested by 18O/16O mapping of volcanic rocks associated with mantle plumes, initially focusing on the Samoa and Guadalupe hotspot chains. A laser fluorination apparatus is being constructed, allowing the analysis of 18O/16O on very small samples; it will be used to study detailed 18O/16O exchange behavior of aqueous fluids and coexisting minerals and volcanic glasses. Two other on-going projects will be completed: (1) Hydrothermal Effects Associated with Chegem Caldera, Caucasus Mtns., Russia. This is the most deeply erode, best exposed, young (2.8 Ma) caldera in the world; it contains a remarkable zone of 18O depletion in a 700 m- thick section of caldera-fill ash-flow tuff, where coexisting phenocrysts and volcanic glass are drastically out of 18O/16O equilibrium. (2) Hydrothermal Systems Associated with Faulting in Metamorphic Core Complexes, British Columbia. This isotopic study of some of the largest metamorphic core complexes in the world will provide new insight into the permeabilities of major fracture zones in the earth's crust, and may help us to understand the role of aqueous fluids in earthquakes.

9317036泰勒低180度热点，如夏威夷，可能代表了回收的低180度洋壳。这一假设将通过18O/16O绘制与地幔热柱有关的火山岩图来验证，最初重点放在萨摩亚和瓜达卢佩热点链上。正在建造一台激光氟化装置，允许对非常小的样品进行18O/16O的分析；它将用于研究水中流体以及共存矿物和火山玻璃的详细的18O/16O交换行为。另外两个正在进行的项目将完成：(1)与俄罗斯高加索山区切盖姆火山口有关的热液效应。这是世界上侵蚀最深、暴露最好的年轻火山口(2.8 Ma)；它在700米厚的火山口充填火山灰流凝灰岩中包含一个显著的18O贫化带，在那里共存的斑晶和火山玻璃严重违反了18O/16O平衡。(2)不列颠哥伦比亚省变质核杂岩中与断裂有关的热液系统。对世界上一些最大的变质核杂岩的同位素研究将为了解地壳主要断裂带的渗透率提供新的见解，并可能有助于我们理解水流体在地震中的作用。