Munir Humayun, an associate professor in FSU’s Department of Geological Sciences and a researcher at the National High Magnetic Field Laboratory, co-authored a paper, “Partitioning of Palladium at High Pressures and Temperatures During Core Formation,” that was recently published in the peer-reviewed science journal Nature Geoscience.
The paper provides a direct challenge to the popular “late veneer hypothesis,” a theory which suggests that all of our water, as well as several so-called “iron-loving” elements, were added to the Earth late in its formation by impacts with icy comets, meteorites and other passing objects.
“For 30 years, the late-veneer hypothesis has been the dominant paradigm for understanding Earth’s early history, and our ultimate origins,” Humayun said. “Now, with our latest research, we’re suggesting that the late-veneer hypothesis may not be the only way of explaining the presence of certain elements in the Earth’s crust and mantle.”
To illustrate his point, Humayun points to what is known about the Earth’s composition.
“We know that the Earth has an iron-rich core that accounts for about one-third of its total mass,” he said. “Surrounding this core is a rocky mantle that accounts for most of the remaining two-thirds,” with the thin crust of the Earth’s surface making up the rest.
“According to the late-veneer hypothesis, most of the original iron-loving, or siderophile, elements” -- those elements such as gold, platinum, palladium and iridium that bond most readily with iron -- “would have been drawn down to the core over tens of millions of years and thereby removed from the Earth’s crust and mantle. The amounts of siderophile elements that we see today, then, would have been supplied after the core was formed by later meteorite bombardment. This bombardment also would have brought in water, carbon and other materials essential for life, the oceans and the atmosphere.”
To test the hypothesis, Humayun and his NASA colleagues -- Kevin Righter and Lisa Danielson -- conducted experiments at Johnson Space Center in Houston and the National High Magnetic Field Laboratory in Tallahassee. At the Johnson Space Center, Righter and Danielson used a massive 880-ton press to expose samples of rock containing palladium -- a metal commonly used in catalytic converters -- to extremes of heat and temperature equal to those found more than 300 miles inside the Earth. The samples were then brought to the magnet lab, where Humayun used a highly sensitive analytical tool known as an inductively coupled plasma mass spectrometer, or ICP-MS, to measure the distribution of palladium within the sample.
“At the highest pressures and temperatures, our experiments found palladium in the same relative proportions between rock and metal as is observed in the natural world,” Humayun said. “Put another way, the distribution of palladium and other siderophile elements in the Earth’s mantle can be explained by means other than millions of years of meteorite bombardment.”
The potential ramifications of his team’s research are significant, Humayun said.
“This work will have important consequences for geologists’ thinking about core formation, the core’s present relation to the mantle, and the bombardment history of the early Earth,” he said. “It also could lead us to rethink the origins of life on our planet.”
Munir Humayun | EurekAlert!
Live from the ocean research vessel Atlantis
13.12.2018 | National Science Foundation
NSF-supported scientists present new research results on Earth's critical zone
13.12.2018 | National Science Foundation
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Physics and Astronomy
14.12.2018 | Health and Medicine
14.12.2018 | Life Sciences