Origin and Deformation of the Ontong Java Plateau

Ontong Java Plateau（OJP）覆盖了200万平方公里的海底，由1亿立方公里的熔岩组成，这些熔岩在120 Ma左右迅速喷发。这一事件代表了从地球内部深处到地表的重大热量和质量转移。这一岩浆事件的原因和与此相关的板块变形，这一巨大的负载是安置不清楚。这些科学家最近的工作已经确定了OJP下方地幔中的地震结构，这种结构只能用与回收的海洋地壳相对应的岩石成分来解释。如果这是真的，这将表明俯冲的海洋板块在地球深处没有完全同化。至少有一部分可以在高温和高压下幸存下来，并被全球地幔环流所捕获。通过对其物理和化学特征的定量估计，验证OJP下方机械强度很强的地幔根的存在，有望进一步了解海洋岩石圈的演化以及大陆板块龙骨的形成和生存。来自日本，英国和美国的科学家团队正在部署海底地震仪，电磁仪，和Ontong Java及其周围的陆基地震站。该项目支持美国科学家和学生参与陆上地震数据的收集和对整个两栖数据集的分析。合并项目的所有地震数据将在所有团队之间共享并进行协作分析。 美国科学家将利用三维全波层析成像技术进行先进的地震分析，并对各向异性和衰减进行表征。新的结果将达到1°分辨率，比目前的~5°分辨率有了很大的提高，这导致了对OJP根部内低速分布的对比解释。教学模块将被创建，并在卡尔顿学院的前沿地球科学网站提供。数据，分析技术和解释方面将纳入本科和研究生课程。

The Ontong Java Plateau (OJP) covers 2 million km2 of seafloor, made up of 100 million km3 lavas that erupted rapidly ~120 Ma. This event represented a major heat and mass transfer from the Earth's deep interior to the surface. The cause of this magmatic event and the associated deformation of the plate on which this large load was emplaced are unclear. Recent work by these scientists has identified seismic structure in the mantle beneath the OJP that can only be explained by rock composition that would correspond to recycled oceanic crust. If true, this would suggest that subducted oceanic plates do not complete assimilate in the deep Earth. At least portions can survive the high temperatures and pressures and be caught up in global mantle circulation. Validating the presence of a mechanically strong mantle root beneath the OJP with quantitative estimates of its physical and chemical characteristics is expected to further understanding of the evolution of the oceanic lithosphere and the formation and survival of continental cratonic keels.A team of scientists from Japan, UK, and US are deploying ocean-bottom seismometers, electromagnetometers, and land based seismic stations on and around the Ontong Java between 2014-2016. This project supports US scientists and students to participate in onshore seismic data collection and analysis of the full amphibious dataset. All the seismic data for the combined projects will be shared among all the team and analyzed in collaboration. The US scientists will conduct advanced seismic analysis using 3-D full-wave tomography, and characterizations of anisotropy and attenuation. The new results would achieve 1° resolution, much improved over the current ~5° resolution that has led to contrasting interpretations of the distribution of low velocity within the OJP root. Teaching modules will be created and made available at Carleton College's On the Cutting Edge Geoscience site. Aspects of the data, analysis techniquest, and interpretation will be incorporated in undergraduate and graduate courses.