En echelon volcanic elongate ridges connecting intraplate Foundation Chain volcanism to the Pacific¯Antarctic spreading center

The development of volcanic elongate ridges (VERs) could be controlled in many cases by complex processes related to interaction between mantle plumes and spreading centers. We report here measured ages for the Foundation Chain, SE Pacific, showing that volcanism along morphologically distinct VERs can develop occasionally as rapidly formed continuous lines of coeval volcanism extending from a region of intraplate volcanism to the Pacific¯Antarctic spreading center. But a significantly more dominant trend is for coeval, yet structurally disconnected, segments of Foundation Chain VERs to develop in a series of en echelon, NE¯SW elongate `zonesʹ of coeval hotspot volcanism. These elongate zones developed at intervals of approximately 1 Myr while maintaining a basically steady state orientation and size as the Pacific¯Antarctic spreading center migrated continually closer to the Foundation plume hotspot. We infer from this new information that Foundation Chain VER development was controlled by an interplay between short-lived, local factors (e.g. location of nearest spreading center segment, lithospheric stress) and long-lived attributes of the Foundation plume hotspot (e.g. size, orientation, periodicity).