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The geology of the Reykjanes Ridge reflects variations in the style of crustal accretion related to mantle plume processes and tectonic reconfigurations. Following a ~30° change in spreading direction, ridge segments progressively reassumed a linear orientation under the influence of a regional mantle melting anomaly. This process is incomplete, with ongoing reorganization along the southernmost part of the ridge. We investigate the ongoing impacts of this reorganization on ridge propagation, seafloor morphology, and structural fabrics using a combination of geophysical evidence to inform the regional and detailed remote-predictive geological mapping over the southernmost ~200 km of the ridge, covering ~11 M.y. of spreading history. Our results show that this area is more segmented than previously described, as we identify two new fracture zones. In this area, transforms evolved to discontinuities between ~8.2 and 4.2 Ma, associated with the evolution of the segments comprising the southern part of the Reykjanes Ridge. At ~9.7–8.2 Ma, a new segment (S2) forms at the expense of segment S3. The evolution of southern most part of the Reykjanes Ridge is related to magma supply associated with buoyant upwelling mantle cells. The elimination of transform motion coincides with reorientation of the seafloor fabric from N-trending at the active plate boundary, to a complex NE-trending fabric in off-axis. This results in dissection of axial volcanic ridges by the oblique plate boundary zone. The complex interplay between segment reorganization and short ridge jumps along the migrating discontinuities results in more crustal accretion to the North American plate overall.
Panasiuk et al. (Fri,) studied this question.