Mantle Terrains and Subduction Signals in Central America

该项目将重点提供中美洲岛弧火山地球化学特征的约束条件。先前在中美洲的研究表明，哥斯达黎加北部和尼加拉瓜南部的火山显示出的地球化学成分与两个具有不同地质历史的地幔地形之间的过渡相一致。本研究的第一部分将重点研究沿这部分弧的喷口熔岩的Pb同位素组成，目的是确定地幔地形边界，并评估下地幔是否受到大约9000万年前这部分板块经过加拉帕戈斯群岛热点的影响。本研究的第二个目标将是通过分析沉积物核心（DSDP 495）中的Ba/La、B/La、U/Th、Ba/Th和U/La，来测量过去2-3个月来弧段陆上俯冲特征的时间变化。这将提供必要的基本地层学和地球化学数据，以发展通过辐合边缘的地幔的沉积物再循环的现实模型。

9628251 Feigenson This project will focus on providing constraints on the geochemical character of island-arc volcanoes in Central America. Previous work in Central America has indicated that the volcanoes in northern Costa Rica and southern Nicaragua display geochemical compositions that are consistent with a transition between two mantle terrains with different geological histories. The first part of this study will focus on the Pb isotopic composition of the lavas from the vents along this portion of the arc with the purpose of defining this mantle terrain boundary and to evaluate if the underlying mantle was affected by the passage of this portion of the plate over the Galapagos hot-spot at about 90 million years ago. The second objective of this study will be to measure the temporal variation in the subduction signature over the last 2-3 my at the segment of the arc immediately onshore by analysing a core of sediments (DSDP 495) for Ba/La, B/La, U/Th, Ba/Th and U/La. This will provide basic stratigraphic and geochemical data necessary to develop realistic models of recycling of sediments through to the mantle at convergent margins.