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

这是一个双船多道地震现场计划，将首次对加勒特断裂带以南东太平洋隆起沿线的地壳结构提供详细的地球物理约束。将收集三种类型的数据：(1)沿东太平洋隆起的20条近距离单船多道地震反射剖面：(2)该地区沿隆起轴和平行于隆起轴的25条双船扩展展开剖面；(3)长700公里的多通道地震反射剖面，沿东太平洋隆起从加勒特断裂带到20.5S处的大型重叠扩张中心。这些数据将被用来检验许多山脊热模型预测的岩浆室大小的扩散率相关性，检验地壳岩浆室与形态、分段和玄武岩地球化学沿轴变化的关系，以及更好地解析洋壳的一阶地震结构，包括莫霍面和地震层3，在地壳形成后的头几十万年里发展起来的。加勒特断裂带以南的东太平洋隆起部分将成为海脊倡议的主要重点。

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.