Collaborative Research: Do symmetric and asymmetric segments on the Mid-Atlantic Ridge have distinct geochemical signatures?

合作研究：大西洋中脊的对称和不对称部分是否具有不同的地球化学特征？

• 批准号: 1061264
• 负责人: Charles Langmuir
• 金额: $ 69.7万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1061264&HistoricalAwards=false
• 关键词: Collaborative; Research; Do; symmetric; asymmetric

The mid-ocean ridge in the Atlantic that separates North American and South America from Europe and Africa is one of the major tectonic plate boundaries on the planet. Only recently has it become obvious that this ridge consists of segments of alternating symmetric and asymmetric spreading, both of which are characterized by different styles of seismicity. A first order question in marine geology is: what causes these differences and do they primarily relate to differences in the mechanical or chemical properties of the crust and underlying mantle. This research sheds new light on this question. It involves an intensive field campaign to sample six adjacent mid-ocean ridge segments that alternate between symmetric and asymmetric spreading. During the campaign, deep submergence tools to identify the presence of previously undiscovered hydrothermal vents will be deployed. Samples of rock and glass dredged from the seafloor will be examined petrographically for mineral associations and to select samples for geochemical analysis. Selected samples will be analyzed for major and trace elements, volatiles, and Sr, Nd, and Pb isotopes. Melt inclusions will also be examined. These data will be used to determine whether magmatic differences that can be related to deeper mantle composition or behavior are the cause of the different types of spreading. Broader impacts of the work include strong integration of research and education. It will result in the development of a course on mid-ocean ridge science for undergraduates that includes analytical laboratory and seagoing field components, with course materials being posted on the web for dissemination. It will also directly train over 10 undergraduates, two graduate students, and two early career researchers. Samples and data collected will be made immediately available to the public and resulting geochemical analyses will be posted on a publicly accessible website. The project also involves a strong component of collaboration with French scientists.

将北美和南美洲与欧洲和非洲区分开的大西洋的大西洋中部山脊是地球上主要的构造板块边界之一。 直到最近，这个山脊才由交替的对称和不对称扩散组成，这两种山脊都以不同风格的地震性为特征。 海洋地质学中的一个第一阶问题是：是什么原因导致这些差异，它们主要与地壳和下层地幔的机械或化学特性的差异有关。 这项研究为这个问题提供了新的启示。 它涉及一项密集的现场运动，以对六个相邻的中山脊区域进行采样，这些山脊在对称和不对称扩散之间交替。 在活动期间，将部署深层浸入式工具，以确定先前未发现的水热通风孔的存在。从海底挖出的岩石和玻璃样品将在岩石岩中检查矿物质关联，并选择样品进行地球化学分析。 选定的样品将分析主要和微量元素，挥发物以及SR，ND和PB同位素。 还将检查熔体夹杂物。 这些数据将用于确定可能与更深层的地幔组成或行为相关的岩浆差异是不同类型扩散的原因。 这项工作的更广泛的影响包括强大的研究和教育。 这将导致开发有关本科生中大海岭科学的课程，其中包括分析实验室和海上野外组件，课程材料在网络上张贴在网络上进行传播。 它还将直接培训10多名本科生，两名研究生和两名早期职业研究人员。 收集的样本和数据将立即向公众提供，因此将发布的地球化学分析将发布在公共访问的网站上。 该项目还涉及与法国科学家合作的重要组成部分。