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posted by chromas on Thursday July 02 2020, @04:30PM   Printer-friendly
from the where-the-mother-lode-gives-birth? dept.

Geologists identify deep-earth structures that may signal hidden metal lodes

If the world is to maintain a sustainable economy and fend off the worst effects of climate change, at least one industry will soon have to ramp up dramatically: the mining of metals needed to create a vast infrastructure for renewable power generation, storage, transmission and usage. The problem is, demand for such metals is likely to far outstrip currently both known deposits and the existing technology used to find more ore bodies.

Now, in a new study, scientists have discovered previously unrecognized structural lines 100 miles or more down in the earth that appear to signal the locations of giant deposits of copper, lead, zinc and other vital metals lying close enough to the surface to be mined, but too far down to be found using current exploration methods. The discovery could greatly narrow down search areas, and reduce the footprint of future mines, the authors say. The study appears this week in the journal Nature Geoscience.

[...] The study found that 85 percent of all known base-metal deposits hosted in sediments-and 100 percent of all "giant" deposits (those holding more than 10 million tons of metal)-lie above deeply buried lines girdling the planet that mark the edges of ancient continents. Specifically, the deposits lie along boundaries where the earth's lithosphere-the rigid outermost cladding of the planet, comprising the crust and upper mantle-thins out to about 170 kilometers below the surface.

Up to now, all such deposits have been found pretty much at the surface, and their locations have seemed to be somewhat random. Most discoveries have been made basically by geologists combing the ground and whacking at rocks with hammers. Geophysical exploration methods using gravity and other parameters to find buried ore bodies have entered in recent decades, but the results have been underwhelming. The new study presents geologists with a new, high-tech treasure map telling them where to look.

Journal Reference:
Mark J. Hoggard, Karol Czarnota, Fred D. Richards, et al. Global distribution of sediment-hosted metals controlled by craton edge stability, Nature Geoscience (DOI: 10.1038/s41561-020-0593-2)

-- submitted from IRC


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  • (Score: 3, Interesting) by khallow on Thursday July 02 2020, @11:47PM

    by khallow (3766) Subscriber Badge on Thursday July 02 2020, @11:47PM (#1015590) Journal
    Consider this. The deepest mine in the world (and possibly the deepest that humans have accessed) is only 4km deep. The deepest artificial point of any sort is the Kola Superdeep Borehole [wikipedia.org] which has achieved depths of over 12 km down (there are longer oil well holes, but these are mostly horizontal and thus not deeper). If we could figure out how to mine (no doubt fully automated) at the depths we can drill to, we could triple the volume of the crust accessible to us.

    This works in spades for celestial bodies that have a far lower surface gravity than Earth. Mars has a third the gravity of Earth. One could go crudely 35 km down before one sees similar pressures. On the Moon which is a sixth the gravity, it's more like 70 km down. Ceres, the largest asteroid, could be drilled all the way to the 480 km deep center without experiencing such pressures (it has 4% of the Earth's surface gravity and the gravitational force drops roughly linearly with depth reaching zero at the center).
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