Indirect Study of Subducted Oceanic Lithosphere at the Central American Margin

PIS计划绘制科科斯板块和纳斯卡板块的地图和采样特征，为推断中美洲俯冲科科斯板块的性质提供基础。基本前提是格里加尔瓦以南的纳斯卡板块以前与尼加拉瓜和哥斯达黎加部分地区的科科斯板块相邻，这一古板块边界可能在下沉板块中形成一个重要的结构。由于仍有一小块碎片未被俯冲，研究人员建议不仅要研究它，还要研究它在秘鲁附近的共轭，那里还有更多的碎片。在这个位置，可以更彻底地绘制结构图，并将结果外推到哥斯达黎加下面的俯冲板块。此外，疏浚将提供必要的样品，以测量中美洲弧下岩石圈的组成。

The PIs plan mapping and sampling features on the Cocos and Nazca plates to provide a basis for inferring the properties of the subducted Cocos plate under Central America. The basic premise is that the Nazca plate south of Grijalva was formerly contiguous with Cocos plate under Nicaragua and parts of Costa Rica and that this fossil plate boundary could form an important structure in the down-going slab. Because a small fragment remains unsubducted, the investigators propose to not only study it, but also it's conjugate off Peru, where much more remains. At that locality, the structure can be mapped more thoroughly and the results extrapolated to the subducted slab beneath Costa Rica. Further, dredging will provide essential samples to measure the composition of the lithosphere that is beneath the Central American arc.