Mapping a Cross-Section through Oceanic Lithosphere Exposed by Vertical Tectonics at the Vema Fracture Zone

Vema断裂带是最北端的缓慢- 沿着中大西洋伸展的长偏移转换断层 在非洲隆起的纬度上的山脊。的形态 断裂带主要是一个平面淹没，沉积物填充 山谷和变换平行的横向脊，塔2， 离谷底4公里。最近一系列的潜水员 法国潜水器Nautile已经表明， 横脊暴露了大洋的所有主要单元 地壳。这个项目试图了解为什么横脊 已经被抬升到邻近的海底之上， 这种隆起的存在，通过检查一个剖面，通过海洋 地壳暴露在横脊的北方侧翼。的 该项目将开始绘制一个200公里长的部分， 横向脊与Hydrosweep和LDGO的多光谱 近海底侧视声纳系统目标是：（1） 绘制垂直运动沿着的断层网络图 发生;（2）确定Vema横嵴是否 在组成和结构上对称;（3）映射几何形状 以及横向上浅水石灰岩帽的范围 （4）地壳厚度的走向变化 单位，地壳剖面整体;（5）成像 地壳与上地幔及地壳单元之间的接触; （6）绘制出露于该地区的席状岩脉的倾角和走向 横脊

The Vema fracture zone is the northernmost of the slow- spreading, long-offset transform faults along the Mid-Atlantic Ridge at the latitude of the bulge of Africa. The morphology of the fracture zone is dominated by a flat-flooded, sediment-filled valley and a transform-parallel transverse ridge that towers 2 to 4 km above the valley floor. A recent series of divers by the French submersible Nautile has shown that the northern flank of the transverse ridge exposes all of the principal units of the oceanic crust. This project seeks to understand why the transverse ridge has been uplifted above the adjoining seafloor, and to exploit the existence of this uplift by examining a section through the oceanic crust exposed on the northern flank of the transverse ridge. The project will begin by mapping a 200 km long section of the transverse ridge with Hydrosweep and with LDGO's multispectral near-bottom-town side-looking sonar system. The objectives are: (1) to map the network of faults along which vertical motion has occurred; (2) to determine whether Vema transverse ridge is symmetrical in composition and structure; (3) to map the geometry and extent of the shallow water limestone cap on the transverse ridge; (4) to along-strike variability in the thickness of crustal units, and the crustal section as a whole; (5) to image the contacts between crust and upper mantle and among crustal units; and (6) to map dip and strike of sheeted dikes outcropping in the transverse ridge.