The submarine Amsterdam-St. Paul (ASP) Plateau, bisected by the Southeast Indian Ridge (SEIR), is a bathymetric high rising ~2 km above the surrounding seafloor that includes the islands of Amsterdam and St. Paul; this excess volcanism is attributed to a mantle hot spot. We obtained new Sr, Nd, and Pb...
Lavas of the Rano Rahi seamount field define a Nd-Pb-Sr isotopic array that connects, and substantially
overlaps, the arrays of the nearby East Pacific Rise axis and 5.6–28 Ma lavas of the Pukapuka ridge
system, situated between the seamount field and French Polynesia. Dating of Rano Rahi samples by
⁴⁰Ar-³⁹Ar...
As the Galápagos hot spot is approached from the west along the Galápagos Spreading Center there are systematic increases in crustal thickness and in the K/Ti, Nb/Zr, ³He/⁴He, H₂O, and Na₂O content of lavas recovered from the spreading axis. These increases correlate with progressive transitions from rift valley to axial...
Within the Australian-Antarctic Discordance (AAD), a boundary exists between isotopically defined “Pacific-type” and “Indian-type” mid-ocean ridge basalt (MORB) erupted along the Southeast Indian Ridge (SEIR). This boundary has migrated westward beneath the easternmost AAD spreading segment at a minimum rate of 25 mm/yr since 4 Ma; however, its long-term history...