Electrical conductivity constraints on the origin of the oceanic asthenosphere

Samer Naif

Presentation information

[EE] Oral

S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Tectonophysics

[S-IT25] [EE] New constraints on the asthenosphere and its role in plate tectonics

Sat. May 20, 2017 10:45 AM - 12:15 PM A02 (Tokyo Bay Makuhari Hall)

convener:William Bythewood Hawley(University of California Berkeley), Hitoshi Kawakatsu(Earthquake Research Institute, University of Tokyo), Kosuke Heki(Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University), Thorsten W Becker(Jackson School of Goesciences, The University of Texas at Austin), Chairperson:William Hawley(University of California Berkeley), Chairperson:Hitoshi Kawakatsu(Earthquake Research Institute, University of Tokyo)

11:30 AM - 11:45 AM

[SIT25-10] Electrical conductivity constraints on the origin of the oceanic asthenosphere

★Invited papers

*Samer Naif¹ (1.Lamont Doherty Earth Observatory)

Recent seafloor magnetotelluric (MT) surveys have imaged the electrical conductivity structure of the oceanic upper mantle. Most regions show high conductivities (0.02 to 0.2 S/m) between 50 and 150 km depths that are inconsistent with dry mantle. Instead, the conductivity observations require either volatiles stored in nominally anhydrous minerals or the presence of interconnected partial melts, leading to dramatically different interpretations on the origin of the asthenosphere. To determine which mechanism is more plausible, I apply several competing empirical models to estimate an upper bound on the conductivity of hydrated oceanic mantle in a thermodynamically self-consistent framework. The results indicate that a subset of the MT observations exceed the maximum conductivity of hydrated mantle regardless of which empirical model is applied.