B" not D" as the source of intraplate volcanism
B" not D" as the source of intraplate volcanism (in In the footsteps of Warren B. Hamilton; new ideas in earth science, Gillian R. Foulger, Lawrence C. Hamilton, Donna M. Jurdy, Carol A. Stein, Keith A. Howard and Seth Stein)
Special Paper - Geological Society of America (May 2022) 553: 371-378
- advection
- boundary layer
- D double prime layer
- fracture zones
- interior
- intraplate processes
- lithosphere
- low-velocity zones
- lower mantle
- mantle
- mantle plumes
- mid-ocean ridges
- ocean basins
- ocean floors
- oceanic lithosphere
- plate tectonics
- plumes
- thermal circulation
- transition zones
- volcanism
- oceanic asthenosphere
- B double prime layer
- LLAMA Model
Under fast-moving oceanic plates, the asthenosphere seismic B" region becomes isolated from the convecting mantle by plate drag and acts as an advecting layer, which can serve as a long-lived source for intraplate volcanism. Geochemical enrichment of B" can occur via infiltration by melts generated from the breakdown of serpentinite at approximately 200 km depth in subducting slabs. Ocean-island chains arise when melts generated within metasomatized B" by shear melting and localized convection are released along lithospheric fractures controlled by the stress field of the plate. Intersection of metasomatized B" with ocean-ridge systems produces oceanic plateaus. A strong anisotropy anomaly (V (sub SH) /V (sub SV) >1) at depths of approximately 150 km in the Pacific asthenosphere marks a metasomatized B" domain that originated in the western paleo-Pacific basin in the Carboniferous, and that is now associated with Hawaiian volcanism. Metasomatized B" can be trapped beneath orogenic belts during continental aggregation and tapped by edge-driven convection upon rifting to produce the correlation between intraplate volcanism and the fabric of sutures in opening ocean basins such as the Atlantic Ocean basin.
