Space Mining. In Southeast Missouri?
William Jud, Geologist
Exploration Manager, Legend Minerals LLC
Fredericktown, Missouri
15 April 2024
There is a lot of interest now in mining Asteroids in Space.
As a commercial venture, this may be profitable. Rare asteroids such as 16 Psyche appear to be rich enough in Platinum-Group metals and other high-value materials that their value might exceed the enormous cost of Space Mining and generate positive cash flow.
But the problems are obvious. NASA, the National Aeronautics and Space Administration, notes that sending a pound of something into orbit costs $10,000 to many tens of thousands of dollars. The operational difficulties of chasing a live Asteroid through Space, using Robots to chip off 50 to 100 tons of rock, and bringing your catch home to market on Earth present a long list of difficulties and dangers.
There may be a better way. Mine ‘fossil’ Asteroids already on Earth.
Lines of empirical and circumstantial evidence are converging toward a Conceptual Model suggesting that a huge, 10 to 12 miles in diameter and 500 Cubic Miles in size (assuming spherical shape), probably a Chondrite, Asteroid may have impacted the Precambrian continent Columbia 1,500,000,000 years ago.
The Precambrian continent Laurentia broke away from Columbia about 1,300,000,000 years ago, moved off of the Asteroid Impact Mantle Plume, and took along the Impact Structure leaving the widening Missouri Gravity Low in the Impact Structure’s wake.
Laurentia was carried on moving Tectonic Plates and eventually became the Craton, or Precambrian ‘basement’ rocks underlying North America today. The Impact Structure and much of the Missouri Gravity Low came to rest in southeast Missouri.
Really big Impacters tend to produce wide, essentially flat, craters such as the largest craters visible on the Moon. Crater diameter tends to be 10 to 12 times the Impactor diameter.
Using the Asteroid Conceptual Model to interpret the circular feature 120 miles wide at the south end of the Missouri Gravity Low shown on the Missouri State Gravity map, and the 10:1 ratio of crater diameter to impactor diameter, gives an estimate of Asteroid diameter as 10 – 12 miles. Assuming a spherical shape and using the equation for radius and volume of 4/3 pi r3, the Asteroid volume was 500 CUBIC MILES as a first approximation.
That’s a big rock!
The enormous Asteroid punched a fracture column through the Precambrian Crust and into the underlying Asthenosphere, starting a Mantle Plume.
The Plume underplated and melted the lower Crust creating Rhyolitic Magma that erupted as the Saint Francois Volcanic Field. That’s when Asteroid minerals exploration gets difficult.
Rhyolitic magma is so hot that the normal impact-indicating materials such as Shocked Quartz, Coesite, Stishovite, Shocked Feldspar, Shocked Zircons, and Shatter Cones, were reset or melted during a vast volcanic destruction of evidence. Shocked Zircons are tough little crystals and may have survived but could be rare, hard to find, and their parent rocks may be difficult to identify.
Southeast Missouri is an Iron Metallogenic Province. Iron Oxide deposits in Precambrian rocks, and numerous filled sinkholes in Cambrian and Ordovician sedimentary host rocks mineralized with Iron Sulfide and Iron Sulfide oxidation minerals, are compatible with Iron transfer from a buried Asteroid primary source of metals.
Chondrite Asteroids’ elemental composition generally is not much different from Gneiss (pronounced “Nice”) and Schist and may not generate useful Geophysical anomalies of Gravity and Magnetism.
Magnetotellurics may work to locate deep fossil Asteroid fragments if the fragments are metals-rich and are not in the shadow of overlying secondary metallic deposits.
Proving the Asteroid Impact Conceptual Model could be as difficult as identifying and removing a single egg from a pan of scrambled eggs.
Drilling could provide proof if the Asteroid is within drilling depth. The Model is proven when drill core begins returning Asteroid rock instead of the surrounding host rock.
Now assume the buried Asteroid does exist and is found at shallow enough depth to allow mining.
Chondrite Asteroids can contain as much as 25% metals. That could be an entire CUBIC MILE OF METAL in every four cubic miles of buried Asteroid. That’s a WHOPPING ENORMOUS amount of metals that include Iron, Cobalt, Nickel, Copper, Gold, Rare Earths, Platinum Group, and others. A full Cubic Mile of recoverable METAL would probably at least double the presently known global resource of metal ORES.
When the Asteroid hit, much of it exploded upward and outward, scattering large chunks throughout a wide area. Directly below the impact, Asteroid fragments measuring many cubic miles could have been driven into the crater floor and survived as ‘fossil’ Asteroid fragments within the older Precambrian gneiss and schist under the younger Precambrian Volcanic rocks.
The huge fragments 10 – 20 or more cubic miles in size, blasted and widely scattered during impact from the estimated 500 cubic miles of the parent Asteroid, likely made their own Impact Craters, melted, recrystallized, and served as raw material that participated in magmatic assimilation and hydrothermal transport that created the Pea Ridge mine Iron ore deposit and other southeast Missouri ‘Olympic Dam-type’ Iron ore deposits including their highly enriched Breccia Pipes. Supergene Enrichment likely happened if the buried Asteroid fragments were later exposed by erosion.
So, there you have it. The Conceptual Model is certainly speculative but appears valid and is supported by available, admittedly sparse, data. Asteroids have been impacting Earth since Day One. Exploration will be difficult for the mentioned reasons. The Asteroid fragments may or may not exist. They may or may not be ore grade. Maybe they are buried 10 miles deep and are beyond mining range. Can we find them?
And maybe they do exist, are shallow and easily mined, rich, and contain gazillions of tons of valuable metals that could reverse our dwindling supply of minerals and provide vital resources for hundreds of years.
Geophysicist Anne McCafferty at the US Geological Survey in Denver, Colorado, published a study (see reference, below) that ties southeast Missouri’s several ‘Olympic Dam-type’ Iron deposits to a regional magmatic source at depth, possibly supporting the Precambrian Asteroid Impact Model as identifying a common source of metallic mineralization.
If buried mineralized Asteroids are such a fantastic potential source of metallic resources, why haven’t several been discovered already?
Because it’s a new Conceptual Model. Nobody has been looking for them.
It’s a fun time to be a Minerals Exploration Geologist!
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REFERENCES. Listed on the www.legendminerals.com website, Supporting Research page.
William Jud: Possible Precambrian Asteroid Impact Structure In Southeast Missouri
James Austin and Clive Foss: Rich, attractive and extremely dense: A geophysical review of Australian IOCGs
Anne E. McCafferty: Crustal architecture beneath the southern Midcontinent (USA) and controls on Mesoproterozoic iron-oxide mineralization from 3D geophysical models.
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Copyright 15 April 2024 by William Jud. Unlimited reproduction is authorized.