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

大西洋的大洋中脊将北美和南美洲与欧洲和非洲隔开，是地球上主要的构造板块边界之一。直到最近才变得明显的是，这个海脊由对称和非对称交替展开的部分组成，这两个部分都具有不同类型的地震活动。海洋地质学中的一个首要问题是：是什么导致了这些差异？它们是否主要与地壳和下伏地幔的机械或化学性质的差异有关？这项研究为这个问题提供了新的线索。它涉及一场密集的野外活动，以采样六个相邻的大洋中脊部分，这些部分在对称和不对称扩散之间交替。在这次行动中，将部署深度潜水工具，以确定以前未发现的热液喷口的存在。将对从海底挖出的岩石和玻璃样品进行岩石学检查，以确定矿物组合，并选择样品进行地球化学分析。将对选定的样品进行常量和痕量元素、挥发物以及锶、钕和铅同位素的分析。还将检查熔融包裹体。这些数据将被用来确定可能与更深的地幔成分或行为有关的岩浆差异是否是不同类型扩散的原因。这项工作的更广泛影响包括研究和教育的紧密结合。这将导致为本科生开发一门关于大洋中脊科学的课程，其中包括分析实验室和海洋实地部分，课程材料将在网上张贴以供传播。它还将直接培训10多名本科生、2名研究生和2名早期职业研究人员。所收集的样本和数据将立即向公众提供，并将在公众可访问的网站上公布所得的地球化学分析结果。该项目还涉及与法国科学家合作的重要组成部分。

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.