Volcanic Sources of Volatile Platinum Group Elements

挥发性铂族元素的火山​​来源

• 批准号: 0538241
• 负责人: Bernhard Peucker-Ehrenbrink
• 金额: $ 27万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538241&HistoricalAwards=false
• 关键词: Volcanic; Sources; Volatile; Platinum; Group

Intellectual Merits:Preliminary data for volcanic aerosols from Vulcan Masaya, Nicaragua, indicate that platinum group element (PGE) concentrations are significantly higher than PGE concentrations in urban air. Urban air is generally considered contaminated with PGE released from automotive catalytic converters. Such aerosol particles regionally contaminate urban areas with Pt, Pd and Rh. Long range transport of such particles is the suspected cause of increasing PGE concentrations in the environment, as recorded in Greenland snow and ice since the mid 1970s. If PGE concentrations measured in volcanic aerosols from Vulcan Masaya are typical of volcanic aerosols in general, volatile PGE emissions are globally significant and merit detailed study. Magmatic fractionation of Re-Os-Ir-Rh-Ru-Pt-Pd is governed by the volatility of relevant PGE-containing complexes (e.g., oxides, hydrogen halides, sulfides) and the physicochemical properties of the magma (temperature, fugacities of relevant chemical species). Preliminary data for volcanic aerosols from Vulcan Masaya, Nicaragua, indicate that PGE abundance patterns are strongly and uniquely fractionated (i.e., high Pd/Pt, Os/Ir, Ru/Rh) compared to other important sources of PGE.These unique patterns, in conjunction with 187Os/188Os, may serve as a unique fingerprint forvolcanic sources of PGEs, provided they are typical for volcanic exhalations in general. If PGEabundance patterns are a unique geochemical indicator of PGE sources in the geologic record, they may have potential applications ranging from the identification of disputed impact layers to assessing origins of PGE concentrations in the environment.We propose to investigate volatility of Re, Os and complementary PGE at magmatic conditions by analyzing aerosol filters (gaseous and particle-bound PGE) from three well-monitored volcanic systems - Pu'u O'o vent of the Kilauea volcano, Hawaii; Vulcan Masaya, Nicaragua; Etna volcano, Italy. These sites encompass a wide spectrum of volcanic systems, i.e., archetypical mantle-plume, intraplate and subduction related volcanoes with significant SO2 fluxes. Our preliminary data from Vulcan Masaya seem to support the hypothesis that volatile PGE abundance patterns, in combination with Os isotope analyses, can be used to distinguish magmatic from anthropogenic and extraterrestrial PGE sources. We propose to analyze a suite of 60-100 samples for Re/Os/PGE and Os isotopic composition. Complementary major and trace element analyses will be carried out to place the Re/Os/PGE data in a broader geochemical context.Broader Impacts:In addition to advancing basic understanding of interaction between the extraterrestrialenvironment, the ocean, crust and mantle, this study will provide research and educationalopportunities (REU) for two undergraduate Summer Student Fellows at WHOI. The project willalso foster international collaborations with scientists in England and France. Peucker-Ehrenbrinkand Sims will continue to participate in a variety of outreach efforts to share our scientific resultswith graduate students in the MIT/WHOI Joint Program and the general public.

知识方面的优点：尼加拉瓜Vulcan马萨亚火山气溶胶的初步数据表明，铂族元素的浓度大大高于城市空气中的铂族元素浓度。城市空气通常被认为受到汽车催化转化器释放的PGE污染。这种气溶胶颗粒使城市地区受到Pt、Pd和Rh的区域性污染。这种颗粒的远距离迁移被怀疑是环境中铂族元素浓度增加的原因，自20世纪70年代中期以来，格陵兰岛的冰雪中就有记录。如果在Vulcan马萨亚火山气溶胶中测量到的PGE浓度是一般火山气溶胶的典型特征，那么挥发性PGE排放具有全球意义，值得进行详细研究。Re-Os-Ir-Rh-Ru-Pt-Pd的岩浆分馏受相关含PGE络合物（例如，氧化物、卤化氢、硫化物）和岩浆的物理化学性质（温度、相关化学物质的逸度）。尼加拉瓜Vulcan马萨亚火山气溶胶的初步数据表明，铂族元素丰度模式具有强烈而独特的分馏（即，高Pd/Pt，Os/Ir，Ru/Rh），这些特征与187 Os/188 Os一起，可以作为火山岩PGE来源的独特指纹，只要它们是火山喷流的典型特征。如果PGE丰度模式是地质记录中PGE来源的独特地球化学指标，那么它们可能具有潜在的应用，从识别有争议的影响层到评估环境中PGE浓度的来源。通过分析气溶胶过滤器在岩浆条件下的Os和补充PGE（气态和颗粒结合的PGE）来自三个监测良好的火山系统--夏威夷的基拉韦厄火山的Pu 'u O 'o喷口;尼加拉瓜的Vulcan马萨亚;意大利的埃特纳火山。这些地点包括广泛的火山系统，即，原型地幔柱，板内和俯冲相关的火山与显着的二氧化硫通量。我们的初步数据从火神马萨亚似乎支持的假设，挥发性铂族元素丰度模式，结合Os同位素分析，可用于区分岩浆的人为和地球外的铂族元素来源。我们建议分析一套60-100个样品的Re/Os/PGE和Os同位素组成。补充的主要和微量元素分析将进行放置在更广泛的地球化学背景下的Re/Os/PGE数据。更广泛的影响：除了推进外星环境，海洋，地壳和地幔之间的相互作用的基本理解，这项研究将提供研究和教育机会（REU）在WHOI的两个本科生暑期学生研究员。该项目还将促进与英国和法国科学家的国际合作。Peucker-Ehrenbrinkand西姆斯将继续参与各种外展活动，与麻省理工学院/WHOI联合项目的研究生和公众分享我们的科学成果。