A Two-Ship Multichannel Seismic Investigation of the East Pacific Rise South of the Garret Fracture Zone

这是一个由两艘船组成的多通道地震现场项目，将首次提供关于Garrett断裂带以南东太平洋隆起地壳结构的详细地球物理约束。将收集三种类型的数据：(1)沿东太平洋隆起的20条近距离、单船多通道地震反射剖面；(2)同一区域沿和平行于上升轴的25条双船扩展扩展剖面；(3)从加勒特断裂带到20.5S大重叠扩张中心沿东太平洋隆起700 km长的多通道地震反射剖面。这些数据将用于检验许多脊顶热模型预测的岩浆房大小对扩张速率的依赖性，检验地壳岩浆房与沿轴形态、分段和玄武岩地球化学变化之间的关系，并更好地解决包括莫霍和地震3层在内的海洋地壳一级地震结构，在地壳形成后的最初几十万年间发展起来的。加勒特断裂带以南的东太平洋隆起部分将成为RIDGE倡议的主要焦点。

This is a two-ship multichannel seismic field program that will provide the first detailed geophysical constraints on the crustal structure along the East Pacific Rise south of the Garrett fracture zone. Three types of data will be collected: (1) twenty closely-space, single-ship multichannel seismic reflection profiles along the East Pacific Rise; (2) twenty- five two-ship expanding spread profiles along and parallel to the rise axis in this same area; and (3) a 700-km-long multichanel seismic reflection profile along the East Pacific Rise from the Garrett fracture zone to the large overlapping spreading center at 20.5S. These data will be used to test the spreading rate dependence of magma chamber size predicted by many ridge crest thermal models, examine the relationship between crustal magma chambers and along-axis changes in morphology, segmentation and basalt geochemistry, and to resolve better how the first-order seismic structure of oceanic crust, including Moho and seismic layer 3, developed during the first few hundred thousand years after crustal formation. The section of the East Pacific Rise south of the Garrett fracture zone is to be a major focus of the RIDGE initiative.