Because Mars is much smaller than the Earth, it has had much less rock-forming activity. Mars has never had continental drift (no true folding mountain chains), and few volcanoes.
So, does this mean that Mars will have a very different crust than the Earth? Are we likely to find stuff like gold, silver, uranium?
Or will Mars be a lot of silicate rock, and little else? Lots of iron oxide, though.
Haven’t read any formal report on surface geology but everyone in the academe says the red color is likely iron oxide. There seems to be lots of it at the surface.That’s were much of your oxygen is locked. I don’t know about having no continental drift but from last I read, the ‘canals’ are plate boundaries. And since you have a volcano as big as Olympus Mons, there has to be some kind of tectonic activity, though perhaps minor compared with that of Earth’s.
So if you have a lot of iron oxide, you might want to look for associated oxides of nickel, chromium, cobalt, titanium.
That’s my armchair geological assessment. How 'bout the other rock busters here?
Some particularly rich Earthbound ore deposits are associated with impact events, so we should find those on Mars too. Several other richones are formed by non-volcanic magma deposits.
So to sum up: nickel, copper, platinum, palladium, gold and chrome could all occur in deposits that don’t depend on sedimentary or epigenetic hydrothermal processes.
Olympus Mons is actually a pretty good indication of very slow or non-existent tectonics. It’s basically a hot-spot volcano like Hawaii, but in Hawaii the Pacific plate is moving over the stationary hot spot, leaving a string of islands, whereas at Olympus Mons the lava is just piling up in one place.
As to the OP, most ore deposits on Earth are either found in or derived from intrusive igneous rocks or metamorphic rocks. These form fairly deep within the crust and it requires tectonics to bring them up to or near the surface. At the moment, there does not seem to be enough tectonic activity* for this to happen, and we don’t currently know enough about the geologic history of Mars at the moment to say if there were conditions in the recent past that would allow ores near the surface.
In general, though, the surface geology of Mars is all volcanic rocks and volcanic-derived sedimentary rocks, none of which are likely to contain anything currently of economic value in currently economically recoverable concentrations.
*There is fairly clear evidence that tectonics at least once existed on Mars. The debate now is whether they’ve shut down or are simply very slow, with the latter theory gaining more traction as of late.
That’s a hasty generalization, I think - what about black smoker sulphides, SedExdeposits, banded ironstones, or the impact deposits I mentioned? And skips over the necessity for sedimentary beneficiation of a lot of primary deposits. Granted, most of those is likely to be of any significance on Mars unless it had significant oceans, but I wouldn’t say “most ore deposits on earth” are intrusive or metamorphic or even derived from them except at so large a remove as to be unconnected.
Unobtainium should be plentiful there. It’s common all over the universe, as far as I can tell. Except on Earth, of course.
Well, I’ll grant you BIF’s (they are indeed sedimentary, but tend to get lumped in with metamorphic rocks in petrology classes). The black smokers and SedEx only work if there’s already crystalline (i.e. metamorphic or intrusive) rock near the surface. In the Sudbury case, that would be considered intrusive igneous, since even though the impact would have formed a small sea of lava, the “goodies” are all in the portions that cooled deep underground. If there were no tectonics on Earth, they would still be many kilometers down.
The fact of the matter is that volcanic rocks have virtually no potential for metals, and (as far as we know) that’s all we’ve got anywhere near the surface on Mars. Perhaps in a future where we were seriously considering mining on other planets, we’d also have better underground mining methods that could get down to where there might be potential goodies (in which case mining the craters might be an excellent strategy), but with current mining techniques I doubt there’d be anything of value up there.
Virgin volcanic rock (unaltered) do have ore potential (which I take you to mean mineable metallic deposits.) These are your concentration of ore through magmatic differentiation.
What little sedimentary rocks you might have may already have mineable concentrations of metallic oxides.
As far as I’m aware, black smokers work just fine with extrusives (that’s all they have to work with in their environment), and SedEx works with sedimentary rocks during diagenesis.
That’s completely ignoring the definition of “intrusive igneous” - an impact site’s an impact site.
Nope. There are carbonates, and sandstones and arenaceous rocks on the Martian surface.
Our current techniques take us nearly 4 km down - how deep were you thinking?
Looked it up. So it’s possible carbonatite deposits, not calcareous fossil sediments (silly me.) Bottom line is nearly all igneous intrusives, and that includes carbonatites, have ore concentration potential. Water has nothing to do with carbonatite deposition.
It would be odd, carbonatites are associated with rift tectonics. But a good thing for ore deposits, carbonatites are usually good sources of REEs and other minerals.
I wouldn’t say water has nothing to do with carbonatites - I get what I think you mean, I think, about nothing to do with deposition per se - but fenitization halos usually are an important part of carbonatite terrane.
I’ll admit I’m not entirely up on the black smokers, but I believe you only get decent amounts of valuable metals when they are relatively near the continental shelf, since you have granitic rocks getting recycled into the magma that is heating the smokers. The ones you would find in the middle of a big ocean basin with nothing but unaltered oceanic crust for miles around would still grow sulfide minerals, but none of the ones that are of particular economic interest.
SedEx depends on having “source” sediments that were rich in metals in the first place, which you don’t have without an intrusive or metamorphic source.
The definition of intrusive igneous is an igneous rock that cools underground. When you get huge impact like the Sudbury event, you get a huge amount of decompression melting that makes a huge amount of magma in the impact crater. That magma body then cools from the top down, so only the very top layer is truly extrusive, with the rest cooling underground, thus being considered an intrusive rock.
The impact ore bodies only form when there are very large impacts and the resultant magma bodies are very deep and take a long time to cool down. The economically valuable material is going to be in the material that crystallizes last and since it’s cooling from the top down, that means the good stuff is at the bottom.
Well, okay, there are some very trace amount of carbonate rocks up there. Most of the sedimentary rocks up there are just reworked volcanics. Neither amount to any sort of source of metals.
On Earth most of the big ore-bearing intrusive bodies are thought to have been implanted somewhere between 5 and 50 km in depth. I have no idea what that would translate to with Martian gravity and geothermal gradient, but I suspect it will be deeper.
See what I said about “except at so large a remove as to be unconnected” - ultimately, *all *rocks are derived from either intrusives or extrusives. You seem to be arguing that extrusives have no chance of bearing economic quantities of ores without a granitoid somewhere close. But that doesn’t have to be the case - in fact, VMSes are usually closely associated with felsic volcanics. And no, the mid-ocean rift-associated VMSes are just as likely to have significant ore genesis.
I’m not disputing associated magmatic sequences, I’m disputing that the impact melt itself is classed as an igneous intrusive - cite?
Not always - some incompatible minerals may end up on top because they remain in the magma and that pulses out on top of previous cumulate phases - like Bushveld chromite layers. There’s no law that says top-down cooling is the only way a magma body cools, or we wouldn’t have layered intrusions of the Bushveld type.
Define “trace” - it looks like the carbonates are pretty pervasive. Whole percentages of carbonates isn’t “trace” in my book.
What are you basing this certainty on?
Why not shallower, if Martian gravity is 1/2 Earth’s?
Why is there so much iron oxide on the surface of Mars?
One theory is that it’s because Mars is so much smaller than Earth, so (back in the Noachian epoch when the surface would have been molten) the molten surface layer never reached the temperatures where its iron was stripped of oxygen and migrated to the core, like it did on Earth.
…or, it’s just surface rust on rocks, mainly silicates. But yeah, there may be less concentration at the core than with earth’s. Then again, on earth, you have just about all the iron you need at the surface and somewhat abundant nickel, chromite, copper, etc. You even have a lot of gold, so the differentiation isn’t all that thorough.
Is this worth a thought?
Interplanetary dust is high in nickel IIRC. Mars’ atmosphere is thinner and less effective at deflecting particles it runs into. That which lands on the surface stays where it landed for the most part due to a lack of water-driven erosion. Therefore there may be a significant amount of nickel on the surface than there is on Earth.
Mars may not have water-driven erosion, but it seems to have a bit of wind-driven erosion and temperature-driven weathering. Which, when it comes to heavy minerals, might actually be a good thing - a density 3x that of silica is definitely going to lead to selective transport and occasional pockets of enrichment. But I think we’d be better off going straight for the motherlode of actual meteorites, of which Mars should have plenty - dust would be harder to extract commercially even with magnetic separation.