Ore resources on Mars

Mars may contain valuable ores that will be very useful to future colonists.^[1] The abundance of volcanic features together with widespread cratering are strong evidence for a variety of ores. ^[2]

How deposits are made

A strong tenet of basic geology is that ore deposits are produced with the help of large amounts of heat. On Mars, heat can come from molten rock moving under the ground and from crater impacts. Liquid rock under the ground is called magma. When magma sits in underground chambers, slowly cooling over thousands of years, heavier elements sink. These elements, including copper, chromium, iron, and nickel become concentrated at the bottom.^[3] When the mass of magma has cooled down and has mostly frozen or crystallized into a solid, a small amount of liquid remains. This liquid bears important substances such as lead, silver, tin, bismuth, antimony.^[4] When magma is fresh and hot, many elements are free to move. Later, as cooling proceeds, the elements hook up or bind with each other to form chemical compounds or minerals. Some hook up quickly, others much later. Because some elements do not fit easily into minerals (some are just too big), they often exist as free elements even after nearly all the other elements have formed minerals. These remaining elements are called incompatible elements.^[5][6] Some of them are quite useful for our species: niobium, a metal used in producing superconductors and specialty steels, lanthanum and neodymium used by Toyota to build its Prius cars, europium for television monitors and energy-efficient LED light bulbs ^[7] Sometimes minerals are so hot in the magma chamber that they are in the form of a gas. Others are mixed with water and sulfur. The gases and mineral-rich solutions eventually work their way into cracks and become valuable minerals veins. Ore minerals, including the incompatible elements, remain dissolved in the hot solution, then crystallize out when the solution cools. Hot liquids can hold much more solid in solution, just as hot tea can hold more sugar then cold tea. Deposits created by means of these hot solutions are called hydrothermal deposits. Some of the world's most significant deposits of gold, silver, lead, mercury, zinc, and tungsten started out this way.^[8][9][10] Nearly all the mines in northern Black Hills of South Dakota came to be because of hot water desposits of valuable minerals.^[11] Cracks often form when a mass of magma cools because magma, like most substances, contracts when it cools. Cracks occur both in the frozen magma mass and in the surrounding rocks, so ore is deposited in any kind of the rock that happens to be nearby, but the ore minerals first had to be concentrated by way of a hot, molten mass of magma.^[12]

Molten rock on Mars

The surface of Mars displays areas of great heat in the past with its huge volcanoes, including Olympus Mons--the largest volcano in the solar system. Even Ceraunius Tholus, one of its smaller volcanoes, nears the height of Earth's Mt. Everest.

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  Olympus Mons Region showing several large volcanoes.

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  Lower volcano is Ceraunius Tholus and upper volcano is Uranius Tholus as seen by Mars Global Surveyor Mars Orbiter Camera. Ceraunius Tholus is about as high as Earth's Mount Everest.

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  Lava flow, as seen by THEMIS. Note the shape of the edges

What's more there is strong evidence for much more widespread sources of heat in the form of dikes, which indicate that magma traveled under the ground. Dikes take the shape of walls and cut across rock layers.^[13] In some cases dikes on Mars have become exposed by erosion.

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  Possible dike in Syrtis Major quadrangleas seen by HiRISE under the HiWish program.

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  Dikes in Arabia, as seen by HiRISE, under the HiWish program. These straight features may indicate where valuable ore deposits may be found by future colonists. Scale bar is 500 meters.

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  Straight ridges may be dikes in which liquid rock once flowed. Image is of Huo Hsing Vallis in Syrtis Major, as seen by THEMIS.

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  Dike near the crater Huygens shows up as narrow dark line running from upper left to lower right, as seen by THEMIS.

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  Dikes as seen by HiRISE under the HiWish program. Image in Nilosyrtis region, in Casius quadrangle.

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  Dikes near Spanish Peaks, Colorado. Dikes like these are common on Mars

Large areas of Mars contain troughs, called fossa, which are classified as grabens by geologists. They stretch thousands of miles out from volcanoes.^[14] It is believed that dikes helped with the formation of grabens.^[15][16][17] Many, maybe most, of the grabens had dikes under them. One would expect dikes and other igneous intrusions on Mars because geologists believe that the amount of liquid rock that moved under the ground is more than what we see on the top in the form of volcanoes and lava flows.^[18] On Earth, vast volcanic landscapes are called "large Igneous Provinces" (LIP's); such places are sources of nickel, copper, titanium, iron, platinum, palladium, and chromium.^[2][19] Mars's Tharsis region contains a group of giant volcanoes, is considered to be an LIP.

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  Graben in Memnonia Fossae, as seen by HiRISE. This graben is believed to be the result of magmatic dikes rather than regional tectonic stretching. The scale bar is 1000 metres long.

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  Cerberus Fossae in the Elysium quadrangle, as seen by HiRISE

Heat from impacts

The Main asteroid belt (white) and the Trojan asteroids (green). Click on image to see more. Note how close the orbit of Mars is to the asteroid belt.

Besides heat generated by molten rock, Mars has had much heat produced when asteroids impacted its surface making giant craters. The area around a large impact may take hundreds of thousands of years to cool.^[2]

243 Ida and its moon Dactyl. Dactyl is the first satellite of an asteroid to be discovered.

During that time, ice in the ground will melt, heat, dissolve minerals, then deposit them in cracks or faults that were produced with the impact. Studies on the earth have documented that cracks are produced and that secondary minerals veins are filled in the cracks.^[20][21][22] Images from satellites orbiting Mars have detected cracks near impact craters.^[23] The surface of Mars contains abundant evidence of a wetter climate in the past along with ice frozen in the ground. NASA's Mars Odyssey actually measured the distribution of ice from orbit with a gamma ray spectrometer.ref>http://mars.jpl.nasa.nasa.gov/odyssey/newsroom/pressreleases/20020528a.html</ref> This process, called hydrothermal alteration has been found in a meteorite from Mars. Research, published in February 2011, detailed the discovery of clay minerals, serpentine, and carbonate in the veins of a Nakhlite martian meteorite.^{[24] [25]}The Phoenix lander, whose rocket engine blast actually exposed a layer of ice, watched ice melt (the ice disappeared by sublimation).^[26][27]

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  Hellas Basin Area topography. This is one of the impacts that would have taken many thousands of years to cool. A great deal of minerals could have been deposited while this area was cooling.

• False colour of Hellas Planitia.jpeg

  Hellas Basin with graph showing the great depth of the crater. It is the deepest crater on Mars.

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  Topography of the Argyre Basin, the major feature in the Argyre quadrangle. This large impact crater would have also taken many thousands of years to cool.

Direct evidence for valuable materials

Nakhla meteorite, one of many pieces of Mars that have landed on the Earth. Visible are its two sides and its inner surfaces after breaking it in 1998

It has for some time been accepted by the scientific community that a group of meteorites came from Mars. As such, they represent actual samples of the planet and have been analyzed on Earth by the best equipment available. In these meteorites, called SNCs, many valuable elements have been detected. Magnesium, Aluminium, Titanium, Iron, and Chromium are relatively common in them. In addition, lithium, cobalt, nickel, copper, zinc, niobium, molybdenum, lanthanum, europium, tungsten, and gold have been found in trace amounts. It is quite possible that in some places these materials may be concentrated enough to be mined.^[28]

The Mars landers Viking I, Viking II, Pathfinder, Opportunity Rover, and Spirit Rover identified aluminium, iron, magnesium, and titanium in the Martian soil.^[29] Opportunity found small structures, named "blueberries" which were found to be rich in hematite, a major ore of iron.^[30] These blueberries could easy be gathered up and reduced to metallic iron that could be used to make steel.

"Blueberries" (hematite spheres) on a rocky outcrop at Eagle Crater. Note the merged triplet in the upper left.

In addition,both Spirit and Opportunity Rovers found nickel-iron meteorites sitting on the surface of Mars.^[31][32] These could also be used to produce steel.^[33]

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  Heat Shield Rock was the first meteorite ever identified on another planet. It is 93% iron.

Pathfinder's Sojourner Rover is taking its Alpha Proton X-ray Spectrometer measurement of the Yogi Rock (NASA). This instrument measured the elements in the rock.

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  Viking lander took this picture of the Martian surface and analyzed the soil.

Dark sand dunes are common on the surface of Mars. Their dark tone is due to the volcanic rock called basalt. The basalt dunes are believed to contain the valuable minerals chromite, magnetite, and ilmenite.^[34] Since the wind has gathered them together, they do not even have to be mined, merely scooped up.^[35] These minerals could supply future colonists with chromium, iron, and titanium.

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  Dark dunes (probably basalt) which form a dark spot in Noachis quadrangle. Picture from Mars Global Surveyor.

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  Wide view of dunes in Noachis, as seen by HiRISE.

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  Close-up View of dunes in previous image, as seen by HiRISE. Note how sand barely covers some boulders.

What's next

Theoretically, valuable ore resources exist on Mars.^[35] Moreover, we can predict where to look for them, such as around craters and near volcanic regions. As more images are gathered, we will be able to better map the locations of smaller structures, such as dikes, that indicate intrusive (under the surface) igneous activity. Later, flying unmanned craft with gravity and magnetic measuring devices will be able to determine the exact locations of mineral deposits. These devices were employed by American scientists to discover deposits of iron, copper, niobium, and gold in Afghanistan.^[36]

See also

• Water on Mars
• Geology of Mars
• Vredefort crater
• Impact crater
• Ore genesis
• hydrothermal circulation
• Igneous differentiation
• Dike (geology)
• Franklin dike swarm
• fossa (geology)
• asteroid belt

References

1. ^ Cordell, B. 1984. A Preliminary Assessment of Martian Natural Resource Potential. The Case For Mars II.
2. ^ ^{a b c} http://news.discovery.com/space/mars-prospecting-ores-gold.html
3. ^ Namowitx, S. and D. Stone. 1975. earth science the world we live in. American Book Company. NY, NY.
4. ^ Sorrell, C. 1973. Rocks and Minerals. Golden Press. NY, NY.
5. ^ http://www.tulane.edu/~sanelson/geol1212/magmadiff.html
6. ^ http://www.newworldencyclopedia.org/entry/Ore
7. ^ www.livescience.com/technology/Rare-Earth-Elements-100614.html
8. ^ http://nevada-outback-gems.com/prospect/gold_specimen/California_quartz_veins.htm
9. ^ http://www.springerlink.com/content/r87p498m051rm18t/
10. ^ http://www.mirandagold.com/s/CoalCanyon.asp
11. ^ ISBN 0-87842-338-9
12. ^ Pirajno, F. 2004. Metallogeny in the Capricorn Orogen, Western Australia, the result of multiple ore-forming processes. Precambrian Research: 128. 411-439
13. ^ http://www.mantleplumes.org/GiantRadDykeSwarms.html
14. ^ Head, J. et al. 2006. The Huygens-Hellas giant dike system on Mars: Implications for Late Noachian-Early Hesperian volcanic resurfacing and climate evolution. Geology: 34. 285-288.
15. ^ Goudy, C. and R. Schultz. 2005. Dike intrusions beneath grabens south of Arsia Mons, Mars. Geophysical Research Letters: 32. L05201
16. ^ Mege, D. et al. 2003. Volcanic rifting at Martian grabens. Journal of Geophysical Research: 108.
17. ^ Wilson, L. and J. Head. 2002. Tharsis-radial graben systems as the surface manifestation of plume-related dike intrusion complexes: Models and implications. Journal of Geophysical Research: 107.
18. ^ Crisp, J. 1984. Rates of magma emplacement and volcanic output. J. Volcanlo. Geotherm. Res: 20. 177-211.
19. ^ Ernst, R. 2007. large Igneous Provinces in Canada Through Time and Their Metallogenic Potential. Mineral Deposits of Canada: A Synthesis of Major Depotit-Types, District metallogeny, the Evolution of Geological Provinces, and Exporation Methods: Geological Association of Canada, Mineral Division, Special Publication No. 5. 929-937.
20. ^ Osinski, G, J. Spray, and P. Lee. 2001. Impact-induced hydrothermal activity within the Haughton impact structure, arctic Canada: Generation of a transient, warm, wet oasis. Meteoritics & Planetary Science: 36. 731-745
21. ^ http://www.ingentaconnect.com/content/arizona/maps/2005/00000040/00000012/art00007
22. ^ Pirajno, F. 2000. Ore Deposits and Mantle Plumes. Kluwer Academic Publishers. Dordrecht, The Netherlands
23. ^ Head, J. and J. Mustard. 2006. Breccia Dikes and Crater-Related Faults in Impact Craters on Mars: Erosion and Exposure on the Floor of a 75-km Diameter Crater at the Dichotomy Boundary. Special Issue on Role of Volatiles and Atmospheres on Martian Impact Craters Meteoritics & Planetary Science
24. ^ http://www.spaceref.com/news/viewpr.html?pid=32629
25. ^ H. G. Changela and J. C. Bridges. Alteration assemblages in the nakhlites: Variation with depth on Mars. Meteoritics & Planetary Science, 2011 45(12):1847-1867 DOI: 10.1111/j.1945-5100.2010.01123.x
26. ^ Rayl, A. J. S. (2008-06-21). "Phoenix Scientists Confirm Water-Ice on Mars". The Planetary Society web site. Planetary Society. http://www.planetary.org/news/2008/0621_Phoenix_Scientists_Confirm_WaterIce_on.html. Retrieved 2008-06-23. 
27. ^ Confirmation of Water on Mars
28. ^ Hugh H. Kieffer (1992). Mars. University of Arizona Press. ISBN 9780816512577. http://books.google.com/books?id=NoDvAAAAMAAJ. Retrieved 7 March 2011. 
29. ^ Fairen, A. et al. 2009. Nature: 459. 401-404.
30. ^ Squyres, et al. 2004. The Opportunity Rover's Athena science investigation at Meridiani Planum. Science: 306. 1598-1703.
31. ^ Rodionov, D. et al. 2005. An iron-nickel meteorite on Meridiani Planum: observations by MER Opportunity's Mossbauer Spectrometer, European Geosciences Union in Geophysical Research Abstracts: 7. 10242
32. ^ Yen, A., et al. Nickel on Mars: constraints on meteoritic material at the surface. Journal of Geophysical Research-Planets: 111. E12S11
33. ^ Landis, G. 2009. Meteoritic steel as a construction resource on Mars. Acta Astronautica: 64. 183-187.
34. ^ Ruzicka, G. et al. 2001. Comparative geochemistry of basalts from the Moon, Earth, HED asteroid, and Mars: implications for the origin of the Moon. Geochimica et Cosmochimica ACTA: 65. 979-997.
35. ^ ^{a b} West, M. and J. Clarke. 2010. Potential martian mineral resources: Mechanisms and terrestrial analogues. Planetary and Space Science: 58. 574-582.
36. ^ http://nytimes.com/2010/06/14/world/asia/14minerals.html?page watched=2