REU: SeaMARC II Investigations of the Mid-Atlantic Ridge Between 24'N and 29'N and the Australian-Antarctic Discordance

这是一个关于研究大洋中脊系统两个区域构造的两个野外项目的建议。主要工具是SeaMARC II，这些数据将由重力和磁力数据补充。第一个研究区域是北纬24至29度的大西洋中脊。沿裂谷的轴向不连续面和形态构造变化将连续覆盖至少100公里的距离。主要目标是了解沿缓慢扩张中心的火山和构造活动的变化，抵消MAR的小轴向不连续的性质，以及导致MAR分割的地幔过程。第二个项目侧重于澳大利亚-南极不协调带（AAD）。这是洋中脊系统中一个独特而鲜为人知的区域，其特征是崎岖的地形和广泛的轴向形态。地球物理数据将由疏浚计划补充。目标是(1)绘制区域图，确定该区域的构造构造和时间演化；(2)确定该区域的地球化学不连续的性质，以及AAD的标记边界的性质；(3)确定地球化学、构造构造、重力、以及AAD内外的磁场，以了解其性质、起源和演变。这些项目使用了一种重要的、相对较新的工具来探索沿洋中脊的海底结构。从这些研究中获得的数据将提供有关洋中脊系统及其构造和火山演化的重要信息。

This is a proposal for two field programs to study the tectonics of two regions of the mid-ocean ridge system. The principal tool is SeaMARC II, and these data will be complemented by gravity and magnetics data. The first region of study is the Mid-Atlantic Ridge from 24 to 29 degrees North latitude. Continuous coverage of the axial discontinuities and the morphotectonic variations along the rift valley over a distance of at least 100 km will be obtained. The main objective is to understand the variations in volcanic and tectonic activity along a slow spreading center, the nature of small axial discontinuities that offset the MAR, and the mantle processes that lead to segmentation of the MAR. The second project focuses on the Australian-Antarctic Discordance (AAD). This is a unique and poorly understood region of the mid-ocean ridge system, characterized by rugged topography and a wide range of axial morphologies. The geophysical data will be complemented by a dredging program. The objectives are (1) to map the region and determine the tectonic structure and the temporal evolution of the region, (2) to determine the nature of geochemical discontinuities in the region, and the nature of the marked boundaries of the AAD, and (3) to determine the interrelationships among geochemistry, tectonic structure, gravity, and magnetics within and outside of the AAD in an effort to understand its nature, origin and evolution. These projects use an important, relatively new tool for exploring the structure of the sea floor along mid-ocean ridges. The data obtained from these studies should provide important information about the mid- ocean ridge system and its tectonic and volcanic evolution.