Geochemistry of the Hollister Ridge: relation with the Louisville hotspot and the Pacific–Antarctic Ridge
Résumé
The Hollister Ridge is located on the western flank of the Pacific–Antarctic Ridge (PAR), between the Udintsev fracture zone (FZ) and the Eltanin fault system. It is a linear aseismic structure, 450 km long, oblique with respect to the PAR. Data show that the most recent activity is located in the central part of the chain, which can be considered as being still volcanically active. Both major/trace element and isotopic data suggest that some interaction occurred between the Pacific–Antarctic Ridge and the Hollister Ridge. The source of the Hollister Ridge samples has its own geochemical characteristics. The geochemical variations observed along the ridge can be explained by mixing between two major end-member components: (1) a PAR depleted source, and (2) a Hollister enriched source. A small contribution (20% maximum) of Louisville plume material is likely to exist in the middle of Hollister Ridge. These data unequivocally reject the possibility that the Hollister Ridge could be the present location of the Louisville hotspot. Ages and geochemistry data support the idea of an influence of intraplate deformation as a probable cause of the origin of the Hollister Ridge.