The relative motions of tectonic plates are well established, but the motion of the underlying mantle is poorly known. Silver and Holt (p. 1054) determined the motion of the mantle beneath western North America by combining observations of surface deformation with uppermantle seismic-velocity anisotropy. The upper mantle is flowing to the east, opposite the westward motion of the North American...

The components of rock-forming and accessory minerals of the upper mantle, transition zone and lower mantle rocks have been involved into the processes of diamond genesis. Through their dissolving in primary carbonate melts, the mantle minerals have turned into components of the parental silicate-(±oxide)carbonate-carbon melts-solutions for diamonds and co-crystallized paragenetic minerals. The...

The formation of oblique ribs of bivalve shells usually has been attributed to processes of reaction-diffusion of morphogens from cell to cell at the mantle margin or neural activation and lateral inhibition in the mantle. In particular, such ribs appear with high rates of lateral diffusion. Nevertheless, theoretical models fail to explain either partially or wholly some varieties of oblique ri...

The present study was designed to test the hypothesis of an oxygen limitation defining thermal tolerance in the European cuttlefish (Sepia officinalis). Mantle muscle organ metabolic status and pHi were monitored using in vivo 31P NMR spectroscopy, while mantle muscle performance was determined by recording mantle cavity pressure oscillations during ventilation and spontaneous exercise. Under c...

We examine two prominent upper mantle velocity anomalies in the southwest Pacific, the Tonga slab anomaly and the corresponding ov. erlying mantle wedge anomaly, using data collected during a combined land-sea deployment of temporary seismometers. The linear geometry and small interstation spacing of the instruments yield high-resolution data along a cross section of the Tonga subduction zone, ...

Primitive, low-silica and high-alkali magmas that erupt late in the evolution of most ocean island volcanoes are highly enriched in incompatible trace elements, yet their isotopic compositions require a time-integrated mantle source history of incompatible-element depletion. Reconciling these observations has traditionally required either extremely low degrees of partial melting of depleted man...

D″ (Dee double prime), the lowermost layer of the Earth's mantle, is the thermal boundary layer (TBL) of mantle convection immediately above the Earth's liquid outer core. As the origin of upwelling of hot material and the destination of paleoslabs (downwelling cold slab remnants), D″ plays a major role in the Earth's evolution. D″ beneath Central America and the Caribbean is of particular geod...

[1] Several methods have been developed to assess the thermal state of the mantle below oceanic ridges, islands, and plateaus, on the basis of the petrology and geochemistry of erupted lavas. One leads to the conclusion that mantle potential temperature (i.e., TP) of ambient mantle below oceanic ridges is 1430 C, the same as Hawaii. Another has ridges with a large range in ambient mantle potent...

We investigate the coupled effects of mineralogy and pressure on the dynamics of axisymmetric thermochemical plumes in the lower mantle, using both high resolution numerical experiments and simple analytical theory. We focus on the effect of composition on the compressibility which has not been studied before. Our results show that the effect of mineralogy is considerable: For relatively low Si...

We review the resolution currently available with seismic tomography, in particular the ability of seismic waves to image mantle plumes, and discuss frequently asked questions about artifacts, interpretation and possible systematic errors. These aspects are discussed in more detail for two case histories offering different problems in the tomographic interpretation: Iceland and Hawaii. Regional...