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

大西洋的洋中脊将北美和南美与欧洲和非洲分开，是地球上主要的构造板块边界之一。直到最近才变得明显，这个脊是由交替的对称和不对称扩张段组成的，这两段都具有不同类型的地震活动特征。海洋地质学的首要问题是：是什么导致了这些差异？它们主要与地壳和地幔的机械或化学性质的差异有关吗？这项研究为这个问题提供了新的线索。它包括一个密集的实地活动，对六个相邻的海洋中脊段进行采样，这些脊段在对称和不对称扩散之间交替进行。在这次活动中，将部署深埋工具来识别以前未被发现的热液喷口的存在。从海底打捞的岩石和玻璃样本将进行岩石学检查，以确定矿物组合，并选择样本进行地球化学分析。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。熔体夹杂物也将被检查。这些数据将用于确定岩浆差异是否与更深的地幔成分或行为有关，是否是不同类型扩张的原因。这项工作的更广泛影响包括研究和教育的强有力整合。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上实地组成部分，课程材料将在网上发布以供传播。它还将直接培养10多名本科生、2名研究生和2名早期职业研究人员。收集的样本和数据将立即提供给公众，并将结果地球化学分析结果公布在一个公众可访问的网站上。该项目还涉及与法国科学家合作的一个重要组成部分。

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.