Investigation of Axial Magma Chamber and its Segmentation Beneath the East Pacific Rise 9°N from Seismic Data

It is believed that the discontinuities that are readily seen along spreading centers in bathymetric data are related to magma supply within the crust. The Axial Magma Chambers (AMC) within which the magma supply is pounding have been imaged before but the resolution of the multichannel seismic data (MCS) was not sufficient to clearly define geometry of the AMC along the whole segment and deduct any relationship between the surface discontinuities and the behavior of the AMC. In the summer 2008 we conducted the first academic multi-streamer MCS survey. The survey included one 3D cross axis box at 9°50'N and several ridge parallel lines that we used for 3D (where three or more parallel lines were collected) and 2D processing. The AMC shows variation in depth that is very well correlated with the discontinuities identified in bathymetry. In the area for which we have 3D seismic data we were able to examine the AMC geometry in more detail and map changes in lineation, discontinued reflection from the top of the AMC (e.g. at 9°44'N and 9°51'N). Interestingly all these mapped changes in AMC are very closely related to locations of the bathymetrically expressed discontinuities.