GEOCHEMISTRY OF THE HOLLISTER RIDGE - RELATION WITH THE LOUISVILLE HOTSPOT AND THE PACIFIC-ANTARCTIC RIDGE

The Hollister Ridge is located on the western flank of the Pacific-Ant arctic Ridge (PAR), between the Udintsev fracture zone (FZ) and the El tanin fault system. It is a linear aseismic structure, 450 km long, ob lique 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 isoto pic data suggest that some interaction occurred between the Pacific-An tarctic Ridge and the Hollister Ridge. The source of the Hollister Rid ge samples has its own geochemical characteristics. The geochemical va riations observed along the ridge can be explained by mixing between t wo major end-member components: (1) a PAR depleted source, and (2) a H ollister enriched source. A small contribution (20% maximum) of Louisv ille plume material is likely to exist in the middle of Hollister Ridg e. These data unequivocally reject the possibility that the Hollister Ridge could be the present location of the Louisville hotspot, Ages an d geochemistry data support the idea of an influence of intraplate def ormation as a probable cause of the origin of the Hollister Ridge. (C) 1998 Elsevier Science B.V. All rights reserved.