lower mantle


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Related to lower mantle: crust, upper mantle, Oceanic crust, Outer core, Gutenberg Discontinuity

lower mantle

[′lō·ər mant·əl]
(geology)
The portion of the mantle below a depth of about 600 miles (1000 kilometers). Also known as inner mantle; mesosphere; pallasite shell.
References in periodicals archive ?
We predicted (1) smaller scallops, which are more vulnerable to predators, would have more eyes than larger scallops; and (2) because the upper mantle is hypothesized to be in a better position to detect predators, the upper mantle will have more eyes than the lower mantle.
Sure enough, in spots where the mantle is believed to flow downward, the researchers saw a shift in the type of seismic waves, indicating that the waves were hitting the proposed melting region between the transition zone and the lower mantle.
They wrote: "Our results suggest the lower mantle can store considerable amounts of water.
That combination makes up as much as 20 percent of the lower mantle, says Lin.
Based on the data from that test, the researchers made computer models of Earth's interior, and verified what geologists have long suspected - that a diamond-rich layer likely exists in Earth's lower mantle, just above the core.
G, 2004, Subduction zone processes and implications for changing composition of the upper and lower mantle, in Treatise on Geochemistry, ed.
That suggests that the Loa and Kea chains of volcanoes are venting material that originated in different chunks of the lower mantle.
The trough associated with the mid-oceanic ridges is deeply depressed, and on occasion extends into the lower mantle.
Washington, Sept 16 (ANI): Scientists have found that the carbon cycle, upon which most living things depend, reaches much deeper into the Earth than generally supposed, all the way to the lower mantle, after analysing the chemistry of an unusual set of Brazilian diamonds.
Others contend that propagating cracks in the lithosphere create oceanic islands, that plumes do not exist, that the upper and lower mantle are isolated and depleted, and that MORB and OIB form from the same upper-mantle reservoir.
Recently, geologist Kei Hirose of the Tokyo Institute of Technology and his colleagues mixed up blends of elements that, when heated under intense pressure, transform into the three most common minerals in Earth's lower mantle.
When they did, they found that the behaviour of the dense, alpha-lead oxide form of silica did not match up with any global seismic signal detected in the lower mantle.

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