Sentences with phrase «mantle boundary»

A review of emerging research suggests that field variations on the order of tens of millions of years may be linked to changes in heat flow across the core — mantle boundary.

An alternative suggestive and original explanation is also offered, in which pressure changes at the core — mantle boundary cause surface deformations and relative sea level variations.

Maybe it's all seismic events at the core - mantle boundary, maybe only half, maybe none and it's some blend of thermohaline events, volcanism, etc..

Then all we got left to worry about is getting scorched by the heat from seismic events at the core - mantle boundary.

If seismic events at the crust - mantle boundary are responsible as I suggested, sustained volcanism might be so well correlated with this (whether positively or negatively does not matter) that they may be inseparable.

The core - mantle boundary becomes increasingly viscous with increasing pressure at increasing depth, whence one can expect increasing «friction» leading to build - up of stress that is suddenly released on a quasiperiodic basis, possibly sychronized both with and by resonances in the cavity occupied by the mantle.

A few months after my sawtooth model of the AMO (i.e. mid-2013) I concluded that the mechanism I suggested in column 4 of that poster, namely seismic interference at the core - mantle boundary, CMB, would be too strongly damped to yield any sort of reliably oscillatory behavior, and my 2013 talk at AGU FM makes no mention of any oscillation except the 20 - year magnetic Hale cycle, which can be seen clearly even in CET back to the end of the Maunder minimum.

Since samples from the core - mantle boundary should have indistinguishable cooling rates, MG pallasites could not have cooled at this location.»

«We're getting stronger evidence that there's something unusual about the core - mantle boundary under Africa that could be having an important impact on the global magnetic field.»

Temperatures at the core - mantle boundary hover around 4,000 Kelvin (6,740 degrees F, or 3,727 degrees C), and the pressure is nearly 140 gigapascals — 1.4 million times greater than standard air pressure at sea level.

But scientists have long recorded dramatic drops in the speeds of seismic waves near the core - mantle boundary, leading some experts to speculate that this region is partially melted.

But despite widespread acceptance of the deep plume theory, geoscientists have failed to produce seismic imaging of just such a mushroom - shaped plume extending 3,000 kilometers down to the core - mantle boundary.

Ma, X., Sun, X., Wiens, D., Nyblade, A., Anandakrishnan, S., Aster, R., Huerta, A., Wilson, T., Strong scatterers near the core - mantle boundary, north of the Pacific anomaly, from PKP precursors recorded by Antarctic arrays, proc.

Pressures in the lower mantle start at 237,000 times atmospheric pressure (24 gigapascals) and reach 1.3 million times atmospheric pressure (136 gigapascals) at the core - mantle boundary.

Led by Geophysical Laboratory's Ho - kwang «Dave» Mao, the research team believes that as much as 300 million tons of water could be carried down into Earth's interior every year and generate deep, massive reservoirs of iron dioxide, which could be the source of the ultralow velocity zones that slow down seismic waves at the core - mantle boundary.

The lower mantle comprises 55 percent of the planet by volume and extends from 670 and 2900 kilometers in depth, as defined by the so - called transition zone (top) and the core - mantle boundary (below).

These seismic measurements enabled scientists to visualize these ultralow velocity zones in some regions along the core - mantle boundary, by observing the slowing down of seismic waves passing through them.

Led by Carnegie's Ho - kwang «Dave» Mao, the research team believes that as much as 300 million tons of water could be carried down into Earth's interior every year and generate deep, massive reservoirs of iron dioxide, which could be the source of the ultralow velocity zones that slow down seismic waves at the core - mantle boundary.

The scientists infer that late in the magma - ocean crystallization, iron - rich pyroxene and ilmenite, which formed late and at the crust - mantle boundary, might have begun to sink, and early - formed magnesium - rich olivine might have begun to rise.

The billion - year cycle of molten rock rising from the core - mantle boundary and falling from the crust — not unlike the motion of globules in a lava lamp — takes form, as do other geologic features of interest.

Currently, the team is focused on imaging the entire globe from the surface to the core - mantle boundary, a depth of 1,800 miles.

Tiny regions of compositionally distinct rock (red material, known as ultra-low velocity zones), collect at Earth's core - mantle boundary (tan surface), nearly halfway to the center of our planet.

Employing such reservoirs into their models is supported by geophysical observations of two, continent - sized regions — one below the Pacific Ocean and one below parts of the Atlantic Ocean and Africa — sitting atop the core - mantle boundary.

Based on their results, there appears to be a massive circular blob of partially molten rock, approximately 800 kilometers in diameter and 15 kilometers in height, along the core - mantle boundary, feeding the plume directly below the basaltic island.

This moves the small pockets of chemically distinct rocks to the edges of the hotter blobs above the core - mantle boundary.

Around the Earth's core - mantle boundary are regions called ultralow - velocity zones (ULVZs), which are characterized by liquid rock with velocities up to 30 % lower than surrounding material.

The finding, in combination with evidence from previous studies, suggests that these molten regions deep below, near the core - mantle boundary of the Earth, may cause basaltic ocean island chains to form along the surface.

And he finds that, along the core - mantle boundary, the currents are lateral, drawn toward the bases of plumes like an upside - down bathtub drain.

The new study completes that picture down to the core - mantle boundary.

This supports models where the material in the plume is a mixture of normal mantle rock and primordial rock from the dense rock anchoring the plume at the core - mantle boundary.

Previous attempts to image mantle plumes have detected pockets of hot rock rising in areas where plumes have been proposed, but it was unclear whether they were connected to volcanic hotspots at the surface or the roots of the plumes at the core mantle boundary 2,900 kilometers (1,800 miles) below the surface.

The ratio of the radii of the two spheres is identical to that between the Earth's inner core and the core - mantle boundary.

«We still haven't traced a plume all the way to the core - mantle boundary, but the evidence we have so far points to that region as the most logical source.»

The study shows that the carbon cycle extends deep into mantle, possibly all the way down to the core - mantle boundary, with billion year storage times.

The map showed the seismic speeds varied more than expected over these distances and were probably driven by heat transfer across the core - mantle boundary and radioactivity.

NASA researchers have found that several volcanic deposits on Mercury's surface require mantle melting to have started close to the planet's core - mantle boundary, which lies only 400 km below the planets surface and making it unique in the solar system.

Tomogram of the lowermost mantle (on top of core - mantle boundary, such as in our paper) centred on the equatorial region north of Australia.

This is the pressure of Mercury's core - mantle boundary.»

We don't know the character of the core - mantle boundary.

So to answer your question (which I take to be about explanation), not much until I get buy - in from others about whether my explanation (in terms of seismic events at the two mantle boundaries) is at all realistic.

Not exact matches

If the Tories are serious in their bid to claim the mantle of opposition, then they would need to win this seat, which Labour worried about losing in 2011 (given the Conservative favourable boundary changes).

Hotspots were thought to be caused by a narrow stream of hot mantle convecting up from the mantle - core boundary called a mantle plume, the latest geological evidence is pointing to upper - mantle convection as a cause.

Finally, volcanoes can be caused by «mantle plumes,» so - called «hotspots;» these hotspots can occur far from plate boundaries, such as the Hawaiian Islands.

The region is located right above the boundary between the hot liquid outer core and the stiffer, cooler mantle.

The underside of the mantle — the boundary between it and the liquid outer core — is probably rugged terrain.

This process could account for certain heat pulses in the outer core and at its boundary with the Earth's mantle.

Unlike the Earth, it has a large core and a comparatively shallow mantle, meaning that the mantle - core boundary is only around 400 km below the planet's crust.

Her research concentration is in marine geophysics, where she has used a variety of remote sensing techniques from ships and space to probe the dynamics of the mantle and overlying plates far from plate boundaries on geologic time scales.

This scenario included an increased amount of dense, silicon - rich basalt rock in the lower mantle, below the megameter boundary.

Of the many scenarios for mantle chemical composition the researchers tested, one most closely resembled the real world and included the possibility that slabs can stall at the megameter boundary.