The Nevada Bureau of Mines and Geology releases a new report on the state's lithium, and a new study examines plate subduction and copper mineralization.
By chance, I saw a video on YouTube explaining why 75 elements (out of 118 total periodic elements) are used in our mobile phones. Mining and minerals are core parts of geology—today more so than ever before. This edition will cover two main ingredients for electrification: lithium and copper.
Rasoul Sorkhabi
Editor, Core Elements
Nevada’s Lithium Rush
Neil Lockhart/ Shutterstock.com
The Nevada Bureau of Mines and Geology (NBMG) has published a 40-page informative report entitled Lithium in Nevada. Let’s take a look.
About Silver Peak:
Silver Peak in Nevada has been the state’s only lithium mine since 1966. Before that, Silver Peak was a silver mining town.
Today, Albemarle Corp. produces 5,000 metric tons of lithium carbonate from Silver Peak brine annually.
New reserves from Nevada:
The NBMG has estimated lithium resource base and proven reserves for 17 specific deposits in Nevada.
Of these deposits, only three are brine; the rest are clay-hosted deposits.
The data are expressed in millions of metric tons of lithium carbonate equivalent (Mt.LCE)
The report estimates 4.28 Mt.LCE lithium reserves for clay-hosted deposits and 0.36 Mt.LCE for brines.
These two sources total 5.92 Mt.LCE, which translates to 2.8 billion EV equivalent—the number of electric cars that could be produced if all of the reserves were extracted.
Top three deposits in Nevada:
Thacker Pass, operated by Lithium Americas, is the state’s largest lithium deposit. It is located at the southern end of McDermitt Caldera—which erupted 16 million years ago—on the Nevada-Oregon border. Thacker Pass’s resources base is 19.1 Mt.LCE and estimated reserves are 3.7 Mt.LCE.
Clayton Valley, operated by Century Lithium Corp., has 6.67 Mt.LCE resource base and 1.76 Mt.LCE reserves. It is located in a fault-bounded valley formed as part of the Great Basin extensional tectonics.
Rhyolite Ridge, operated by Ioneer USA Corp., hosts clay-hosted lithium and boron deposits within the Pliocene-age Cave Spring Formation. It has 3.35 Mt.LCE resource base and 0.58 Mt.LCE reserves of lithium.
Why it matters: Domestic production of lithium is key to national security and economic development.
According to the U.S. Geological Survey, batteries account for 87 percent of global lithium use. This may increase to 95 percent by 2030, mainly fueled by demand for electric vehicles.
United States imports of lithium are from Argentina (51 percent), Chile (43 percent), China (3 percent), Russia (2 percent), and others (1 percent).
“As geoscientists, we get to work on some of the biggest projects and challenges our world is facing... I thoroughly enjoy seeing how we as an industry continue to innovate and how it unlocks new opportunities globally”—Diane Woodruff, Occidental Offshore U.S.
Porphyry copper deposits (PCDs) account for 60 percent of the annual world copper production and more than 95 percent of the United States’ copper production. How the formation of these minerals is controlled by deep tectonics is an attractive problem for geologists—scientifically and economically.
Subduction zone model:
PCDs are largely associated with subduction zones, in which a dense oceanic plate subducts beneath a light, granite-rich continental plate.
Dehydration of the subducting slab produces metal-rich magmas that rise within the mantle wedge above the slab.
The rising magmas go through chemical differentiation, and PCDs are produced.
But there is a problem: This model is understandable if the subduction takes place at high angles. However, about 10 percent of subduction zones are flat-slab type, with few subducting angles, which leaves no room for a mantle wedge between the subducting slab and the overriding continent.
A new study from Arizona: Lamont and colleagues have taken on this problem, examining the Laramide Porphyry Province in Arizona.
There, during the Laramide orogeny, from Late Cretaceous to Paleocene, the Farallon oceanic plate on the Pacific side subducted beneath the North American continental plate in a flat-slab geometry.
New results: The researchers conducted geochemical and geochronological analyses of granitic intrusion in Arizona associated with PCDs.
Neodymium isotopic signatures from the sample indicate that the metals originated from an ancient Proterozoic continental crust rather than a younger mantle.
Garnet-clinopyroxene assemblage in the rock samples further support the origin of copper from the Proterozoic lower crust before the Laramide orogeny.
New model: The researchers suggest that during the flat subduction of the Farallon plate, large amounts of hot water were introduced from the subducting slab directly into the lower crust and caused “anatexis” or partial melting of crustal rocks. Anatexis was thus responsible for the generation of PCDs.
Why it matters: If this new model is correct, it implies that other flat-slab subductions may undergo similar mineralization processes.
Go deeper: Read the new study by Lamont and colleagues in Nature Geoscience.
A Message From AAPG Academy and ThinkOnward
Register now to join AAPG Academy and ThinkOnward on 12 February at 9am CST for a free webinar covering a unique approach to geoscience data management using AI.
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Here is the answer to last week’s quiz: What are the most abundant and the rarest elements in the universe and on Earth?
The most abundant element in the universe is hydrogen (92 percent)—the simplest element formed after the Big Bang. The most abundant element in the Earth’s crust is oxygen (46.6 percent), but if we consider Earth as a whole, iron tops the list (32 percent) followed by oxygen (30 percent). The rarest naturally occurring element on Earth and in the universe is astatine (At, atomic number 85), which is radioactive with short-lived isotopes (half-life of 8.1 hours). The total amount of astatine at a given time on Earth is estimated to be 25 grams.
Here is this week’s quiz question: Of the 17 rare-earth elements, which one is the rarest?
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