Some refractory rocks from the ultra-slow spreading Gakkel ridge (Arctic Ocean) have model ages up to 2 billion years, implying the long-term preservation of refractory domains in the asthenospheric mantle rather than their erasure by mantle convection. It is suggested that the upwelling mantle beneath mid-ocean ridges is highly heterogeneous, which make its composition difficult to be constrained by mid-ocean ridge basalts alone.
- Chuan-Zhou Liu
- Jonathan E. Snow
- Albrecht W. Hofmann
