Chlorine Isotope Geochemistry of Volcanic Systems

火山系统的氯同位素地球化学

• 批准号: 0711533
• 负责人: Jaime Barnes
• 金额: $ 13.89万
• 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: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711533&HistoricalAwards=false
• 关键词: Chlorine; Isotope; Geochemistry; Volcanic; Systems

Intellectual merit. To better understand the effects of recycling of surface materials to the mantle at subduction zones, it is proposed to measure the content and isotopic composition of chlorine (Cl) in magmas and aqueous fluids from volcanoes in the Central American and Marianas volcanic arcs. Ideally, the isotopic composition (37Cl/35Cl ratios) potentially can provide critical information regarding the source of the Cl in these types of samples. Earlier work by the PIs shows that different reservoirs in subducting oceanic slabs have distinctive Cl isotopic composition, but also indicate that significant isotopic variation occurs in fumarolic gases due to isotopic fractionation associated with selective outgassing of HCl from aqueous ? thereby complicating interpretation of gas samples. It is proposed to carry out systematic studies of lavas and tephras from well-characterized active volcanoes to better constrain the Cl budget at selected sites. A laboratory study will be conducted to quantify isotopic fractionation between silicate melts and coexisting aqueous vapor, with the aim of improving interpretations of Cl data for volcanic gases. Finally, time-series studies will also be conducted on gases, and perhaps lavas, at the waxing Poas volcano in an attempt to understand how Cl systematics vary in response to increased magmatic inputs over time. Broader impacts include support for an early-career female post-doctoral scientist (Jaime Barnes) and involvement of several undergraduates in data acquisition and interpretation. Results from the proposed research project will be coupled with previous data for subduction zone lavas and ongoing work on oceanic island basalts and integrated into science classes for pre-service teachers to enhance understanding of geologic processes and geochemical recycling in the Earth''s mantle.

智力上的优点。为了更好地了解在俯冲带的地幔表面物质的再循环的影响，建议测量的内容和同位素组成的氯（Cl）的岩浆和水流体中的火山在中美洲和马里亚纳火山弧。理想情况下，同位素组成（37 Cl/35 Cl比率）可能提供有关这些类型样品中Cl来源的关键信息。 PI的早期工作表明，不同的水库在俯冲洋板块有独特的氯同位素组成，但也表明，显着的同位素变化发生在philocolic气体由于同位素分馏与选择性脱气的HCl从水？从而使气体样品的解释复杂化。 有人建议进行系统的研究，熔岩和火山岩的特征良好的活火山，以更好地限制氯预算在选定的网站。 将进行一项实验室研究，以量化硅酸盐熔体和共存的水蒸气之间的同位素分馏，目的是提高火山气体的Cl数据的解释。 最后，还将进行时间序列研究的气体，也许熔岩，在不断上蜡Poas火山，试图了解如何Cl系统学的变化，随着时间的推移增加岩浆输入。更广泛的影响包括对一位职业生涯早期的女博士后科学家（海梅巴恩斯）的支持，以及几名本科生参与数据采集和解释。从拟议的研究项目的结果将与以前的数据俯冲带熔岩和正在进行的工作大洋岛屿玄武岩和纳入科学类职前教师，以提高地质过程和地球化学循环的理解在地球的地幔。