Crustal Structure at the Hess Deep: Geophysical Studies in Support of Deep Crustal Drilling

赤道太平洋东部的赫斯深海是一个裂缝 山谷提供了一个暴露的年轻地壳产生的快速- 在东太平洋海隆上蔓延在裂缝的墙壁里 一个正常的海洋地壳的一部分，可用于采样 学习基底壁中存在下地壳岩石 和裂谷底部表明在赫斯深海钻探 将提供地壳深成层的岩石， 浅地幔钻探这些深层地壳岩石的建议 被JOIDES高度评价。 本奖项将支持详细的地球物理研究， 限制该地区的地壳结构， 钻井具体而言，该项目将进行海底 地震和重力实验来阐明速度和密度 拟建钻井周围区域的结构 地点这些测量将有助于测试不同的模型 在赫斯深海， 底辟作用或低角度拆离断层作用。此外， 将对东太平洋的西侧进行短期调查 地壳隆起，与赫斯深渊共轭， 赫斯地壳形成时的扩张历史

The Hess Deep, in the eastern equatorial Pacific, is a rift valley providing an exposure of young crust produced by fast- spreading on the East Pacific Rise. In the walls of the rift valley a section of normal ocean crust is available for sampling and study. The presence of lower crustal rocks in the basal wall and rift valley floor suggests that drilling within the Hess Deep will provide rocks from the plutonic layers of the crust and shallow mantle. A proposal for drilling these deep crustal rocks has been highly ranked by JOIDES. The present award will support a detailed geophysical study to constrain the crustal structure in the region proposed for drilling. Specifically the project will undertake sea-floor seismic and gravity experiments to elucidate velocity and density structure in the region surrounding the proposed drilling locations. These measurements will help to test differing models for exposure of deep crustal layers in Hess Deep by serpentine diapirism or by low-angle detachment faulting. Additionally, a short survey will be done of the west flank of the East Pacific Rise on crust which is conjugate to Hess Deep to define the history of spreading when the Hess Deep crust was formed.