Eclogites upper mantle

Barth MG, Foley SF, Horn 1 (2002) Partial melting in Archean subduction zones constraints from experimentally determined trace element partition coefficients between eclogitic minerals and tonahtic melts under upper mantle conditions. Precamb Res 113 323-340... 

In large part, this ability of anhydrous basaltic eclogites to seismically blend into an ultramafic mantle arises from the behavior of elastic moduli in pyroxenes. In the shallowest upper mantle, orthopyroxene is —6% slow in Vp relative to olivine and about equal in Vj. However, the bulk... 

Anderson D. L. (1979) The upper mantle transition region Eclogite Geophys. Res. Lett. 6, 433-436. 

O Hara M. I., Saunders M. L, and Mercy E. L. P. (1975) Garnet-peridotite, primary ultrabasic magma and eclogite interpretation of upper mantle processes in kimberlite. Phys. Chem. Earth 9, 571 -604. 

Pyle J. M. and Haggerty S. E. (1994) Silicate-carbonate liquid immiscibility in upper mantle eclogites evidence of natrosilicic and carbonatitic conjugate melts. Geochim. Cosmochim. Acta 58, 2997-3011. 

Schulze, D. J. 1989. Constraints on the abundance of eclogite in the upper mantle. Journal of Geophysical Research, 94, 4205-4212. 

Similar observations have been made in the younger crust of the Sierra Nevada batholith in the USA, where Ducea and Saleeby (1998) proposed that the very thin granite crust (30-40 km), underlain by peridotitic upper mantle, can be explained by the delamination of a thick eclogitic root. Boyd et al. (2004) support this view with evidence from a seismic tomographic study which shows the descent of a two layer slab comprising an eclogitic upper part and a peridotitic lower part, into the mantle. This may be the only place on Earth where dense material is currently being removed from the continental crust into the mantle. 

Deep global cycling of carbon constrained by the solidus of anhydrous carbonated eclogite under upper mantle conditions. Earth Planet. Sci. Lett., 227, 73-85. 

The basalt - gabbro (the amphibole - in the case of water presence) transition to eclogite happens in upper mantle at the continental condition. 

---