Geophysical Studies near the Ascension Transform: Evolution of Ridge Segmentation and Crustal Structure - Auswertung

2004年底，流星巡航M62/4将在升降变换断层区域收集一个大型地球物理数据集，目的是研究扩张轴的分段。要讨论的具体问题包括：从扩展段中心向末端移动的地壳和上地幔结构的变化，以及具有发达的中谷和轴向高压的扩展段之间的变化；活动改造带和非活动断裂带(分别位于内角和外角)附近的地段末端之间的不对称性；大洋核杂岩的演化(通过沿拆离断层的运动挖掘出深地壳和地幔岩石的穹状暴露，其特点是上表面波纹)。将使用的工具包括：广角地震剖面，以确定地壳结构，并结合现有的重力数据，以约束最上面地幔的热结构；高分辨率地震反射研究(包括深拖缆)，以成像上层大洋地壳的结构(断裂和岩浆室)；微震活动和利用海底仪器网格进行的断层成像研究，以确定当地的三维地壳结构和断层活动及力学；条带水深测量和磁学。该提案要求提供支持，以便能够对这些数据进行全面分析。

In late 2004 Meteor cruise M62/4 will collect a large geophysical dataset in the region of the Ascension Transform fault with the aim of studying the segmentation of the spreading axis. Specific questions to be addressed are: the change in crustal and upper mantle structure moving from the centre of a spreading segment towards the end and between spreading segments with a well-developed median valley and a well-developed axial high; the asymmetry between segment ends adjacent to the active transform and the inactive fracture zone (inside and outside corners respectively); the evolution of oceanic core complexes (domal exposures of deep crustal and mantle rocks exhumed by movement along detachment faults and characterised by corrugated upper surfaces). Tools to be used include: wid-angle seismic profiles to determine crustal structure and in conjunction with existing gravity data to constrain the thermal structure of the uppermost mantle; high resolution seismic reflection studies (including a deep tow streamer) to image the structure of the upper oceanic crust (faulting and magma chambers); microseismicity and tomographic studies using a grid of ocean bottom instruments to determine local 3-D crustal structure and fault activity and mechanics; swath-bathymetry and magnetics. This proposal requests support to enable the complete analysis of these data.