Navigation Links
Tiny 3-D images shed light on origin of Earth's core
Date:12/16/2010

To answer the big questions, it often helps to look at the smallest details. That is the approach Stanford mineral physicist Wendy Mao is taking to understanding a major event in Earth's inner history. Using a new technique to scrutinize how minute amounts of iron and silicate minerals interact at ultra-high pressures and temperatures, she is gaining insight into the biggest transformation Earth has ever undergone the separation of its rocky mantle from its iron-rich core approximately 4.5 billion years ago.

The technique, called high-pressure nanoscale X-ray computed tomography, is being developed at SLAC National Accelerator Laboratory. With it, Mao is getting unprecedented detail in three-dimensional images of changes in the texture and shape of molten iron and solid silicate minerals as they respond to the same intense pressures and temperatures found deep in the Earth.

Mao will present the results of the first few experiments with the technique at the annual meeting of the American Geophysical Union in San Francisco on Thursday, Dec. 16.

Tomography refers to the process that creates a three-dimensional image by combining a series of two-dimensional images, or cross-sections, through an object. A computer program interpolates between the images to flesh out a recreation of the object.

Researchers at SLAC have developed a way to combine a diamond anvil cell, which compresses tiny samples between the tips of two diamonds, with nanoscale X-ray computed tomography to capture images of material at high pressure. The pressures deep in the Earth are so high millions of times atmospheric pressure that only diamonds can exert the needed pressure without breaking under the force.

At present, the SLAC researchers and their collaborators from HPSync, the High Pressure Synergetic Consortium at the Advanced Photon Source at Argonne National Laboratory, are the only group using this technique.

"It is pretty exciting, being able to measure the interactions of iron and silicate materials at very high pressures and temperatures, which you could not do before," said Mao, an assistant professor of geological and environmental sciences and of photon science. "No one has ever imaged these sorts of changes at these very high pressures."

It is generally agreed that the initially homogenous ball of material that was the very early Earth had to be very hot in order to differentiate into the layered sphere we live on today. Since the crust and the layer underneath it, the mantle, are silicate-rich, rocky layers, while the core is iron-rich, it's clear that silicate and iron went in different directions at some point. But how they separated out and squeezed past each other is not clear. Silicate minerals, which contain silica, make up about 90 percent of the crust of the Earth.

If the planet got hot enough to melt both elements, it would have been easy enough for the difference in density to send iron to the bottom and silicates to the top.

If the temperature was not hot enough to melt silicates, it has been proposed that molten iron might have been able to move along the boundaries between grains of the solid silicate minerals.

"To prove that, though, you need to know whether the molten iron would tend to form small spheres or whether it would form channels," Mao said. "That would depend on the surface energy between the iron and silicate."

Previous experimental work has shown that at low pressure, iron forms isolated spheres, similar to the way water beads up on a waxed surface, Mao said, and spheres could not percolate through solid silicate material.

Mao said the results of her first high-pressure experiments using the tomography apparatus suggest that at high pressure, since the silicate transforms into a different structure, the interaction between the iron and silicate could be different than at low pressure.

"At high pressure, the iron takes a more elongate, platelet-like form," she said. That means the iron would spread out on the surface of the silicate minerals, connecting to form channels instead of remaining in isolated spheres.

"So it looks like you could get some percolation of iron at high pressure," Mao said. "If iron could do that, that would tell you something really significant about the thermal history of the Earth."

But she cautioned that she only has data from the initial experiments.

"We have some interesting results, but it is the kind of measurement that you need to repeat a couple times to make sure," Mao said.


'/>"/>

Contact: Louis Bergeron
louisb3@stanford.edu
650-725-1944
Stanford University
Source:Eurekalert

Related biology technology :

1. World's First Website for Patients to Share Diagnostic-Quality Medical Images
2. First high-resolution images of bone, tooth and shell formation
3. Amnis Launches New ImageStreamX Imaging Flow Cytometer
4. Physicists capture first images of atomic spin
5. Repligen Announces FDA and EMA Approval of Re-analysis of Images from Phase 3 Trial of RG1068 for Pancreatic Imaging
6. Informed Medical Communications Highlights Opportunity in Revised PhRMA Code
7. DOE JGI Director Eddy Rubin highlights the genomics of plant-based biofuels in the journal Nature
8. Neuralstem Reports Second Quarter Financial Results and Highlights
9. Light touch: Controlling the behavior of quantum dots
10. ChanTest to Highlight the Worlds Largest Catalog of Ion Channel-Expressing Cell Lines and Discovery Services at Ion Channel Targets, Booth 5
11. Explosion Proof Fluorescent Lights Keep Paint Spray Booths and Oil Rig Workers Safe
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/24/2016)... ... May 24, 2016 , ... Media Cybernetics, global ... Media Cybernetics corporate branding reflects a results-driven revitalization for a company with a ... re-branding components include a crisp, refreshed logo and a new web presence. , ...
(Date:5/23/2016)... LONDON , May 23, 2016 ... Boost Efficiency by 40% - Frontage Implement a Single ... Enforce Quality, Compliance and Traceability Within the Bioanalytical lab ... the United States and China ... deployed across its laboratory facilities. In addition to serving as the ...
(Date:5/20/2016)... ... ... Kablooe Design, a leading provider of product design and development services to medical ... “We have worked hard to build long-term relationships,” says President and CEO, Tom KraMer. ... serving their product design and development needs through the years.” , Kablooe has earned ...
(Date:5/19/2016)... , May 19, 2016 ... will fully recover given the relentless pressures in pricing ... sure in the investors circle though - numerous opportunities ... Ahead of today,s session, ActiveWallSt.com,s presents four names in ... ), Vitae Pharmaceuticals Inc. (NASDAQ: VTAE ), ...
Breaking Biology Technology:
(Date:3/22/2016)... Ontario , PROVO and ... Newborn Screening Ontario (NSO), which operates the ... for molecular testing, and Tute Genomics and UNIConnect, ... management technology respectively, today announced the launch of a ... next-generation sequencing (NGS) testing panel. NSO ...
(Date:3/15/2016)... 15, 2016 --> ... Transparency Market Research "Digital Door Lock Systems Market - Global ... 2023," the global digital door lock systems market in terms ... and is forecast to grow at a CAGR of 31.8% ... and medium enterprises (MSMEs) across the world and high industrial ...
(Date:3/11/2016)... 2016 http://www.apimages.com ) - --> ... available at AP Images ( http://www.apimages.com ) - ... to produce the new refugee identity cards. DERMALOG will be unveiling ... in Hanover next week.   --> ... used to produce the new refugee identity cards. DERMALOG will be ...
Breaking Biology News(10 mins):