A Submersible Study of Axial Processes, East Pacific Rise 10-12'N

最近海洋地质研究的一个主要重点是 将地壳的详细地球化学和岩石学 从岩石到沿着洋中脊的精细特征。 海底扩张过程的最初模型假设 地壳是由长而连续的轴向岩浆 钱伯斯虽然在化学上允许有微小的变化， 在这些模型中，喷发熔岩的成分被假定为 保持相当的稳定。随着详细地图系统的出现 例如Seabeam和Seabarc，一个全新的过程类别， 在脊顶水深测量中显示。新的模式出现在 这些数据表明，脊轴是由一系列 小的、离散的岩浆段或单个火山。的 从这些火山产生的熔岩似乎在许多情况下， 化学性质不同 本项目的目标是审查 沿着东部的几个部分的玄武岩化学 太平洋隆起使用研究潜水器阿尔文。先前 水面船只取样确定了玄武岩的总体变化 与重叠扩散等特征有关的化学 中心、偏移脊轴和转换断层。阿尔文现在会 用于在这些特征之间的边界处详细采样。 这些数据将被用来约束的性质和分布 地下岩浆房及其与个人的关系 形态片段沿着嵴轴。 主要研究者完全有资格完成 拟议的项目。

A major emphasis of recent marine geological studies has been to relate the detailed geochemistry and petrology of crustal rocks to the fine-scale features present along mid-ocean ridges. Initial models of the sea-floor spreading process had assumed that crust was created from long, fairly continuous, axial magma chambers. Although minor variations in chemistry were allowed in these models, the composition of the erupted lavas was assumed to be fairly constant. With the advent of detailed mapping systems such as Seabeam and Seamarc, a whole new class of processes were revealed in ridge crest bathymetry. New models emerging from these data indicate that the ridge axis is composed of a series of small, discrete magmatic segments or individual volcanoes. The lavas produced from these volcanoes appears in many cases to be chemically distinct. The objective of the present project is to examine the chemistry of basalts in several of these segments along the East Pacific Rise using the research submersible Alvin. Previous surface ship sampling has defined the gross changes in basalt chemistry related to features such as overlapping spreading centers, off-set ridge axis, and transform faults. Alvin will now be used to sample in detail at boundaries between such features. These data will be used to constrain the nature and distribution of subsurface magma chambers and their relation to the individual morphological segments along the ridge axis. The principal investigators are well qualified to complete the proposed project.