Earth Formation Theory Discredited by New Findings

Earth Formation Theory Discredited by New Findings
Late-veneer hypothesis no longer valid
By Gabriel Gache, Science News Editor
5th of May 2008, 14:27 GMT
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It is widely believed even today that most of the water on our planet along with other 'iron-loving' elements were brought to Earth during the last couple of hundred million years by asteroids, meteorites, comets and other such objects passing through the inner regions of the solar system. FSU's Department of Geological Sciences and National High Magnetic Field Laboratory researcher, Munir Humayun on the other hand thinks otherwise.

"For 30 years, the late-veneer hypothesis has been the dominant paradigm for understanding Earth's early history, and our ultimate origins. 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", says Humayun.To better explain the claims made by the study Humayun had co-authored, he is first detailing the current knowledge of the composition of our planet: "We know that the Earth has an iron-rich core that accounts for about one-third of its total mass. Surrounding this core is a rocky mantle that accounts for most of the remaining two-thirds. According to the late-veneer hypothesis, most of the original iron-loving, or siderophile, elements 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", he said.By pressing samples of rock containing palladium with the help of the Johnson Space Center 880 ton press, Humayun along with Kevin Righter and Lisa Danielson from NASA, recreated the exact conditions experienced by matter while 480 kilometers deep into the Earth. Later investigations with the inductively coupled plasma mass spectrometer from the space center's magnet laboratory revealed the exact distribution of palladium inside 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. 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", he 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. It also could lead us to rethink the origins of life on our planet", said Humayun.