Three-dimensional crustal structure of East Pacific Rise discontinuities from tomographic inversions.

摘要

This thesis discusses the results of seismic tomography experiments investigating the internal structure of the East Pacific Rise (EPR) and its discontinuities. The EPR is not a linear feature but is partitioned by transform faults and non-transform offsets. Within the group of ridge-axis offsets, overlapping spreading centers (OSC) are of particular interest as they are restricted to fast-spreading mid-ocean ridges such as the EPR.; Three seismic refraction surveys centered at an axial discontinuity—the 9°03'N overlapping spreading center, at the center of the fastest spreading segment at 17°30'S, and on the flanks of the same segment, are used to investigate the structure of the EPR and its variability with along-axis segmentation. Counter to earlier predictions, we observe that the 9°03'N overlapping spreading center at the distal end of the 9°N segment does not have a reduced magma supply.