Taxonomy term

mantle

Thirsty mantle: Subduction zones swallow more water than thought

For all the water stored in oceans, ice and other reservoirs at Earth’s surface, there’s likely even more in the planet’s interior, where it plays important roles in many geological processes, including the formation of magma and the lubrication of earthquake-producing fault zones. Uncovering just how much water is inside Earth — and the extent to which it moves back and forth between the surface and subsurface — has long been a challenge for scientists interested in understanding the planet’s water cycle. A new study peering beneath the Mariana Trench in the Western Pacific has revealed that some subduction zones might pull significantly more water into Earth’s interior than previously thought.

30 Jan 2019

Diamonds reveal water in deep mantle

Inclusions in diamonds often render them undesirable to consumers, but they can provide researchers with striking insights into Earth’s composition. Recently, scientists probing diamond samples for the presence of carbon dioxide stumbled instead upon inclusions of ice-VII — a type of crystallized water that forms at very high pressures, and has never before been found in nature.

07 Jul 2018

Young Costa Rican lavas might reflect pockets of primordial mantle

During the Archean, between 4 billion and 2.5 billion years ago, Earth’s super-heated young mantle produced a unique type of lava known as komatiite. In a new study published in Nature Geoscience, researchers looking at 90-million-year-old komatiites in Costa Rica — by far the youngest komatiites ever found — suggest the modern mantle may still harbor pockets of intense heat reminiscent of early Earth.

18 Aug 2017

When and how did plate tectonics begin on Earth?

Earth’s surface is a shifting puzzle of plates that collide and diverge, generating earthquakes, fueling volcanoes, opening ocean basins and raising mountain ranges. But when and how did this process — unique in our solar system as far as we know — begin? 
22 May 2017

Moon formed from pulverized Earth mantle

Scientists have long thought that the moon was formed when an impactor crashed into Earth, some 100 million years after the planet’s formation. But details of this collision, and how the moon formed in its aftermath, remain puzzling. Now, researchers have found new potassium isotopic evidence that suggests the moon condensed from a superheated cloud of Earth’s mantle material after an extremely violent collision vaporized the impactor and much of the proto-Earth.
 

23 Jan 2017

Small-scale factors influence mantle flow under the seafloor

In December 2011, scientists and technicians aboard the research vessel Marcus G. Langseth dropped several ocean-bottom seismometers into the deep Pacific more than 1,900 kilometers southeast of Hawaii to measure seismic activity and electrical conductivity to a depth of about 300 kilometers below the seafloor. Now, these measurements are providing new insights into how the mantle flows and deforms below the rigid tectonic plates that make up Earth’s surface.

22 Nov 2016

Junk gem reveals new diamond-forming process

Not all diamonds are gems. Those found bearing imperfections or inclusions, known as bort or junk diamonds, are often demoted to industrial uses such as in diamond-tipped drill bits. They also sometimes find their way to scientists interested in using the inclusions to study how such stones form. Now, a team studying a junk diamond from Botswana with a large black sulfide inclusion has uncovered evidence of a previously unrecognized diamond formation process that occurs in the deep mantle.

 
16 Sep 2016

Mantle convection makes Earth's crust bob

From the earthquake-prone Himalayas and Andes to the volcanically active “Ring of Fire” around the Pacific, the boundaries of Earth’s tectonic plates are often sites of considerable geologic activity. In contrast, the interiors of tectonic plates have been thought to be relatively rigid and quiet.

18 Aug 2016

Stalled slabs sometimes stopped by mineral strengthening

Subduction of tectonic plates into the mantle functions as an eons-long recycling system for Earth’s crust and lithosphere. But in some subduction zones, the downgoing slabs seem to get stuck at depths of about 1,000 kilometers, held up by some unseen barrier on their journey deeper into the lower mantle. Now, scientists propose that this barrier might be related to high-pressure-induced strengthening of minerals in the rocks surrounding subducting slabs at these depths.
09 Aug 2015

A watery surprise from Earth's depths: Mineral provides first direct evidence for water in mantle's transition zone

From a depth of more than 500 kilometers, Earth has coughed up a water-bearing mantle mineral never before found on the surface. The surprise finding suggests the planet’s interior holds more water than all its oceans combined, and could help explain how Earth’s massive tectonic plates move.

14 Jul 2014

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