Intraplate seamounts research

Thick manganese-oxide crusts precipitated from hydrothermal fluids when the volcano was active and from seawater over time since, making it hard to discern the original rock textures.

Intraplate seamount volcanism is of different types

Many chains of seamounts (submerged mountains) are of hot spot or subduction arc origin. However, some intraplate seamounts have different origins. Near-ridge seamounts erupted near the axes of mid-ocean ridges onto recently derived oceanic crust. In the north-east Pacific, these include the Vance and President Jackson seamounts near the Juan de Fuca and Gorda Ridges, respectively, and the Taney Seamounts off San Francisco, which are no longer associated with an active spreading center (map, 50 kb). Some isolated seamounts and other linear seamount chains have erupted onto much older oceanic crust, and their formation is enigmatic: they do not appear to have erupted as hot spot volcanoes or near-ridge seamounts, and they are not associated with subduction processes. Examples of these include Davidson, Pioneer, and Guide seamounts (map, 118 kb) near the California coast, and the Line Islands chain in the middle of the Pacific Ocean. Note that our work at Axial Seamount is covered in the Mid-ocean Ridge section.