Mapping the Juan Fernandez Ridge (Pacific SW): geomorphogy for understanding volcanic evolution and environmental protection

As most of the oceans worldwide, bathymetry of the Juan Fernandez Ridge (JFR) and surrounding seafloor in the Pacific SW is scarce and still deserves more efforts. Recent advances with new the AGS61 Cabo de Hornos vessel, equipped with a high resolution multibeam ecosounder allows to recognize with unprecedented detail some volcano morphologies. Main motivation for this recent survey was environmental protection of fisheries and endemic fauna, but it is also related with ongoing research about the evolution of the JFR and the competing roles played by mantle and tectonic processes. Here we describe some relevant features as a post-erosional stage at O’Higgins seamount, the oldest ca. 9 Ma component of the ridge that correspond to a paired structure, represented by a radial array of flank cones. .The large edifice has a flat surface at ca. 700 mbsl typical of guyots with also radial rift zones and is connected by a saddle with the smaller eastern seamount. On the western segment, contrasting morphology of JF5 West (Cinque Ports) and JF5 East (Duke) poses a doubt about the age progression along the chain. In fact, Duke is a perfect stellar highly eroded seamount with four rift zones while Cinque Ports is a guyot with post-erosional flank cones. Thus, detailed morphology based on bathymetry and backscatter signal is going to be used for both Earth science research and environmental issues, along with some efforts aimed to establish the extension of the continental shelf beyond the 200 miles.