ABSTRACT:

Marine gravity from satellite altimetry has become a primary tool for investigating the tectonics of the remote ocean basins as well as unexplored continental margins. Recently two new non-repeat altimeter data sets have become available, resulting in a factor of 2-4 improvement in maps of the global marine gravity field.  We use these data along with shipboard bathymetry data and earthquake focal mechanisms to constrain the magnitude of the regional stress field along the global mid-ocean ridge [Luttrell and Sandwell, JGR, 2012].  Slower spreading ridges require at least 25-40 MPa of ridge perpendicular extension while less extensional stress (10-30 MPa) is required at the faster spreading ridges.  Our modeling suggests that a deep transform valley is an essential feature of the ridge-transform spreading center.