The Darwin Rise: a Cretaceous Superswell?

The Japanese Guyots, Wake Guyots, and Mid?-•cific Mountains are part of a broad area of Cretaceous volcanism in the western Pacific termed the "Darwin Rise." Based on Seabeam bathymetric data we classify these drowned volcanic islands as: type "A," those that advanced to the atoll rage before f'mal submergence; type "B," those that drowned at the barrier eef stage; and type "V," those with little or no reef material on their volcanic summits. Widespread evidence for karst topography extending to depths of 200 m on the summits of A and B guyots sheds new light on events leading m the synchronous extinction of reefs on the Darwin Rise in t• mid-Cretaceous. We propose that after the formation of the reefs on the A and B guyots, the entire region was elevated at approximately the Aptian-Albian boundary (113 Ma) to form a superswell similar to that existing now in French Polynesia. •e type V guyots formed on this anomalously shallow I•thosphere. The demise of the reefs was the direct result of the rise of this superswell, although climate factors may have tabvented r ef recolonization following its later subsidence.