Archives par mot-clé : REE

How nodules stay on top at the bottom of the sea

by Geological Society of America, January 13, 2020 in ScienceDaily


Rare metallic elements found in clumps on the deep-ocean floor mysteriously remain uncovered despite the shifting sands and sediment many leagues under the sea. Scientists now think they know why, and it could have important implications for mining these metals while preserving the strange fauna at the bottom of the ocean.

The growth of these deep-sea nodules — metallic lumps of manganese, iron, and other metals found in all the major ocean basins — is one of the slowest known geological processes. These ringed concretions, which are potential sources of rare-earth and other critical elements, grow on average just 10 to 20 millimeters every million years. Yet in one of earth science’s most enduring mysteries, they somehow manage to avoid being buried by sediment despite their locations in areas where clay accumulates at least 100 times faster than the nodules grow.

Understanding how these agglomerations of metals remain on the open sea floor could help geoscientists provide advice on accessing them for industrial use. A new study published this month in Geology will help scientists understand this process better.

“It is important that any mining of these resources is done in a way that preserves the fragile deep-sea environments in which they are found,” said lead author Adriana Dutkiewicz, an ARC Future Fellow in the School of Geosciences at The University of Sydney.

Rare-earth and other critical elements are essential for the development of technologies needed for low-carbon economies. They will play an increasingly important role for next-generation solar cells, efficient wind turbines, and rechargeable batteries that will power the renewables revolution.

REE mineral-bearing rocks found in eastern Mojave Desert

by Geological Society of America, January 2, 2020 in ScienceDaily


Scientists from the U.S. Geological Survey (USGS) have mapped a rare earth element deposit of magmatic carbonatite located in the Mountain Pass region of the eastern Mojave Desert. The new report details the geophysical and geological setting of the deposit, including a map of the deposit’s subsurface extent, to help land-use managers evaluate sites for further exploration. The report was recently published in the Geological Society of America’s online journal, Geosphere.

Rare earth elements (REEs) are critical to emerging industrial technologies including strategic defense, science and medical, automotive and transportation, and civilian electronics. However, large economic REE sources are unique and uncommon worldwide. International concerns about increasing demand and global supply vulnerability have prompted many countries, including the U.S., to explore and assess domestic REE resources. Increased efforts to characterize geologic processes related to REE deposits in the U.S. have focused attention on the world-class Mountain Pass, California, deposit located approximately 60 miles southwest of Las Vegas, Nevada.

In their study, collaborators K.M. Denton and USGS colleagues use geophysical and geological techniques to image geologic structures related to REE mineral-bearing rocks at depth. Their work suggests REE minerals occur along a fault zone or geologic contact near the eastern edge of the Mescal Range. These findings could prove as a useful guide to future exploration efforts.