Scale length of mantle heterogeneities: Constraints from helium diffusion

H profiles in mantle xenoliths: Constraints from diffusion data

Hydrogen concentration gradients reported in olivines from several peridotite xenoliths (Demouchy, 2004; Peslier and Luhr, 2006) have been interpreted as evidence of hydrogen loss during ascent to the surface. However, a review of hydrogen diffusion data in anhydrous minerals (Ingrin and Blanchard, 2006) provides new constraints on the possible origin of these heterogeneities. The amount of hyd...

Tapping of Magmas from Ubiquitous Mantle Heterogeneities' An Alternative to Mantle Plumes?

Long-lived heterogeneities in the mantle are indicated by Nd-Sr-Pb isotopic systematics. Explanations for these variations have invoked either distinct layers in the earth that are preferentially tapped by some source regions (such as plumes rising from the base of the mantle) or small-scale heterogeneities which are ubiquitously distributed through the mantle and tapped differentially in vario...

Length scales of mantle heterogeneities and their relationship to ocean island basalt geochemistry

The upper mantle is widely considered to be heterogeneous, possibly comprising a “marble-cake” mixture of heterogeneous domains in a relatively well-mixed matrix. The extent to which such domains are capable of producing and expelling melts with characteristic geochemical signatures upon partial melting, rather than equilibrating diffusively with surrounding peridotite, is a critical question f...

Shear - Velocity Heterogeneities in the Upper Mantle

Long-period surface waves are used to map lateral heterogeneities of velocity and anisotropy in the upper mantle. The dispersion curves are expanded in spherical harmonics up to degree 6 and inverted to find the depth structure. The data are corrected for the effect of surface layers and both Love and Rayleigh waves are used. Shear wave velocity and shear polarization anisotropy can be resolved...

Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn partitioning during partial melting