Magnetic constraints on volcanic crustal accretion at a fast spreading mid-ocean ridge:
East Pacific Rise 9° N

Maurice A. Tivey, Ph.D.
Woods Hole Oceanographic Institution

Wednesday, January 23, 2002
3:00 p.m.–Pacific Forum

One of the primary lines of evidence for the existence of plate tectonics are the lineated magnetic anomalies found over the ocean basins and symmetrically centered over mid-ocean ridges. One of the basic tenets of plate tectonics is the concept of seafloor spreading, which was accepted based on the irrefutable evidence that magnetic reversals could be correlated between different ocean basins and tied into the geomagnetic polarity timescale. On a broad scale, there is general agreement that seafloor spreading and magnetic reversals are recorded by the ocean crust. On a fine scale, however, the details of this recording process continue to be a topic of vigorous discussion. The relationship between the accretion of volcanic lavas and the fine-scale magnetic anomaly record can be evaluated through high-resolution, near-bottom magnetic surveys, micro-bathymetric and side-scan sonar imaging, and in-situ sampling. The aim of this work is to investigate the possibility that the crustal accretion process, as represented by a lava distribution function, can be deconvolved from the observed anomaly in order to recover the geomagnetic signal.