The largelow-shear-wave velocity provinces (LLSVPs) atop the core-mantle boundary beneath Africa and the Pacific are the largest structures in the lower mantle, and hence severely affect the convective flow. Here, we show that anomalous splitting of Stoneley modes, a unique class of free ...
The compression behavior of the melts is fitted by the Vinet equation of state and extrapolated to higher pressure. A density crossover between the MORB melt and the mantle peridotite is suggested at the base of the lower mantle. Thus, the ultra-low velocity zone in the D″ layer may be...
Density in the upper 170 km of the mantle is about 3.3 g/cm3; this density distribution lends support to the current petrological theory that the upper mantle may be composed of some varieties of peridotite. The mean atomic weight for the lower mantle is about 21.321.5, suggesting the ...
Oceanic crust is mainly composed of Mid-Ocean Ridge Basalt (MORB), which is more silicic than pyrolite. Previous experiments32demonstrated that the natural MORB assemblage at the P–T conditions of lower mantle consists of SiO2silica (stishovite and CaCl2-type silica), calcium perovskite (CaP...
The Earth gets denser going from its outer layers in. The least dense layer is the upper mantle, with density getting larger with the successive layers of the lower mantle, outer core, and finally the inner core. Density can be calculated by dividing the mass by the volume....
It has been proposed that Earth's interior has a fundamental discontinuity at mid-mantle depths of ∼400-1000 km, marking the mantle transition zone (MTZ) between mantle layers below and above (e.g., Bullen, 1940, 1947). The lower boundary of the MTZ was later reclassified as the 660...
It is made up of iron and nickel. Where, then, is the asthenosphere? When the Earth's interior is separated into chunks based on physical characteristics, three distinct layers emerge: the lithosphere, the asthenosphere, and the lower mantle. The lithosphere occupies the crust and some of the...
Thermal expansion of silicate perovskite and stratification of the Earth's mantle A pressure of 24 GPa and temperatures of about 2,000–3,000 K correspond to the observed 670-km seismic discontinuity which separates the upper and lower m... E Knittle,R Jeanloz,GL Smith - 《Nature》 被引量...
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