Melting in the deep upper mantle oceanward of the Honshu slab Journal Article uri icon

DCO ID 11121/5926-1726-4418-9199-CC

in language

  • eng

year of publication

  • 2009

abstract

  • We examine the upper mantle and transition zone beneath the western Pacific using multiple ScS reverberations. A low-velocity zone (LVZ) is found above the 410-km discontinuity oceanward of the subducting Honshu slab at an average depth of 356 km, with a thickness that ranges from 50 to 75 km assuming the LVZ continues to the 410-km discontinuity, which is locally elevated. The low-velocity region is evident in previous tomographic studies, and our results suggest that the anomaly is best explained by a layer of partial melt. The layer may be entrained from above by subduction or produced in situ by the combined effects of water and temperature. A self-consistent model that explains local P-wave velocities (Obayashi, M., Sugioka, H., Yoshimitsu, J., Fukao, Y., 2006. High temperature anomalies oceanward of subducting slabs at the 410-km discontinuity. Earth and Planetary Science Letters 243, 149-158) and our observations calls for a maximum temperature anomaly of similar to 150 degrees C and a resulting maximum olivine water content after melting of 0.100 wt.%. (C) 2009 Elsevier B.V. All rights reserved

volume

  • 175

issue

  • 3-4