The Darwin Rise: A Cretaceous superswell?

The Japanese Guyots, Wake Guyots, and Mid-Pacific 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 stage before final submergence; type “B,” those that drowned at the barrier reef 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 to the synchronous extinction of reefs on the Darwin Rise in the 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. The type V guyots formed on this anomalously shallow lithosphere. The demise of the reefs was the direct result of the rise of this superswell, although climate factors may have prevented reef recolonization following its later subsidence.