Processing and evaluation of our geophysical data, presently in progress, will clarify the complex interactions between the African, South-American and Antarctic lithospheric plates in the Bouvet region. The variability in space and time of the geometry of the plate boundaries and the anomalous topography of the three ridge systems, may be explained in part by the presence of widespread melting/thermal anomalies in the upper mantle below the Bouvet region, as discussed in the first paper produced by our project LIGI1997.
Southern MAR and northwestern SWIR segments, for example, show some features similar to those of fast spreading ridges (overlapping spreading centers, absence of an axial valley, anomalous shallow topography). Bouvet island is considered the surficial expression of a mantle plume MORGAN1972 an interpretation supported by the geochemistry of basalts from this region LEROEX1987.
Geochemical and isotopic work on basaltic glass and ultramafic rock samples is in progress in order to obtain information on the thermal structure and composition of the upper mantle below the entire Triple Junction area.
