Foundation Seamount-Kette Wissenschaftlicher Endbericht

Volcanism has migrated along the NW-SE trending Foundation Chain, SE Pacific, at a rate of 91#+-#2 mm/yr for the past 21 million years (Myr). The Foundation Chain is at least 1900 km long, and was erupted mostly in the interior of the Pacific plate. The linear migration rate of intraplate, often geochemically enriched, volcanism along the Foundation Chain can be explained by the theory of tectonic plate drift over a narrow, stationary plume of hot mantle material upwelling from depth. The present hotspot (or at least its eastern extent) generated by this Foundation plume is now located on, or close to the Pacific-Antarctic spreading-axis. Local spreading/microplate boundaries have migrated systematically towards the Foundation plume for at least the past 21 Myr. This process was, however, interrupted by the creation of the Selkirk microplate. The Foundation Chain has therefore erupted onto ocean crust ranging in age from #propor to# 17 Ma to #>=#0 Ma, with distances between the Foundation plume and local spreading/microplate boundaries varying from #propor to#900 km to #>=#0 km. Such interplay between the plume and local seafloor, spreading-axes and microplate boundaries - probably in combination with changing stresses in the lithosphere - apparently induced major changes in the fabric (and composition) of the Foundation Chain, e.g., the switch from individual seamounts to elongated en echelon ridges at #>=#5 Ma. It can also explain why ages for a few Foundation seamounts located at the edges of the Selkirk microplate do not lie along the overall linear trend of migrating volcanism. (orig.)Summary in GermanAvailable from TIB Hannover: F99B781+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman