Mantle Terrains and Subduction Signals in Central America

9628251 Feigenson本项目将着重于提供中美洲岛弧火山地球化学特征的制约因素。 先前在中美洲的研究表明，北方哥斯达黎加和尼加拉瓜南部的火山显示出的地球化学成分与具有不同地质历史的两种地幔地形之间的过渡相一致。 这项研究的第一部分将集中在火山口的熔岩的铅同位素组成的沿着这部分的弧的目的是确定这个地幔地形边界，并评估如果下面的地幔受到影响的通过这部分板块在加拉帕戈斯热点在约90万年前。 本研究的第二个目的是通过分析沉积物岩心（DSDP 495）的Ba/La、B/La、U/Th、Ba/Th和U/La，测量最近2-3个月内弧段海岸附近俯冲特征的时间变化。 这将提供必要的基本地层和地球化学数据，以建立沉积物在会聚边缘再循环到地幔的现实模型。

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.