2006/07/28 by Naoto Hirano, Eiichi Takahashi, Junji Yamamoto +9 · 6 citations
Earth and Planetary Sciences · #Geological and Geochemical Analysis #earthquake and tectonic studies #High-pressure geophysics and materials
paper · doi:10.1126/science.1128235
openalex publication_date 2006/07/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Volcanism on Earth is known to occur in three tectonic settings: divergent plate boundaries (such as mid-ocean ridges), convergent plate boundaries (such as island arcs), and hot spots. We report volcanism on the 135 million-year-old Pacific Plate not belonging to any of these categories. Small alkalic volcanoes form from small percent melts and originate in the asthenosphere, as implied by their trace element geochemistry and noble gas isotopic compositions. We propose that these small volcanoes erupt along lithospheric fractures in response to plate flexure during subduction. Minor extents of asthenospheric melting and the volcanoes' tectonic alignment and age progression in the direction opposite to that of plate motion provide evidence for the presence of a small percent melt in the asthenosphere.