Galapagos Rise to East Pacific Rise Spreading History

Depth determined seafloor age distribution across the Galapagos Rise suggest a Nazca plate history that has involved nucleation of several transient spreading centers, multiple microplates, and significant rotation of active spreading centers. Curved fracture zones and complex topography displayed in 2 minute gridded bathymetry derived from satellite altimetry (Smith and Sandwell, 1996) imply that the transition to current East Pacific Rise (EPR) spreading involved the evolution and rotation of the Galapagos Rise as an important intermediate stage. The Galapagos Rise system accounts for most of the spreading along the early northwestern Nazca plate from ~20 million years ago (Ma) to possibly as recent as 4-5 Ma. Depth determined plate ages combined with interpretation of magnetic lineations indicate that simultaneous spreading centers were present at both the initiation and failure of the of the Galapagos Rise and spreading transitions occurred by ridge jumps to the current EPR. Magnetic lineations across the Bauer Basin suggest that it was captured between the failing Galapagos Rise and the currently active EPR. An anomalously shallow ridge crest along the Galapagos Rise indicates that ultra slow spreading may have occurred until very recent time (0-5 Ma). Dated magnetic anomalies provide an independant estimate of seafloor age for the region. Reconstruction based on bathymetry and magnetic anomalies provide an evolution for the region that yields new insight into the Galapagos Rise spreading history and the nature of ridge jump phenomenon.