Abstract
Seismic velocities are calculated for two petrological models of the upper mantle, an olivine‐rich assemblage, pyrolite, and a garnet‐clinopyroxene rich, olivine bearing, assemblage, piclogite. These are compared with recent seismic profiles for various tectonic provinces. The shield data is most consistent with a cold olivine and orthopyroxene‐rich LID (the seismic lithosphere) extending to 150 km followed by a high temperature gradient and/or a change in mineralogy that serves to decrease the velocity. From 200 to 400 km the velocities follow a 1400°C adiabat. The rise‐tectonic mantle is much slower, presumably hotter and is likely to be above the solidus to depths of at least 300 km. The high Vp/Vs ratio of the lower oceanic lithosphere in the western Pacific is most consistent with eclogite.
Original language | English (US) |
---|---|
Pages (from-to) | 637-640 |
Number of pages | 4 |
Journal | Geophysical Research Letters |
Volume | 11 |
Issue number | 7 |
DOIs | |
State | Published - Jul 1984 |
Externally published | Yes |
ASJC Scopus subject areas
- Geophysics
- General Earth and Planetary Sciences