Electromagnetic evidence for volatile-rich upwelling beneath the society hotspot, French Polynesia
|Author(s)||Tada Noriko1, Tarits Pascal2, Baba Kiyoshi3, Utada Hisashi3, Kasaya Takafumi1, Suetsugu Daisuke1|
|Affiliation(s)||1 : Japan Agcy Marine Earth Sci & Technol, Yokosuka, Kanagawa, Japan.
2 : Inst Univ Europeen Mer, UMR Domaines Ocean, Plouzane, France.
3 : Univ Tokyo, Earthquake Res Inst, Tokyo, Japan.
|Source||Geophysical Research Letters (0094-8276) (Amer Geophysical Union), 2016-12 , Vol. 43 , N. 23 , P. 12021-12026|
|WOS© Times Cited||9|
|Keyword(s)||hotspot, marine magnetotellurics, three-dimensional inversion, volatiles, partial melt|
We have conducted a seafloor magnetotelluric survey that images, for the first time, three-dimensional electrical conductivity structure in the upper mantle beneath the Society hotspot. A striking feature in our model is a high-conductivity anomaly a few hundred kilometers in diameter, which is continuous from the lowest part of the upper mantle to a depth of approximately 50km below sea level. Using theoretical and experimental results from mineral physics, we interpret the high-conductivity anomaly as evidence of the melt fraction up to 2.2vol.%, which is robust regardless of assumed temperature, and the existence of carbonated silicate melt beneath the hotspot. Our results suggest that the Society hotspot is a pathway for ascending volatiles from the deeper part of the upper mantle to the surface.