I'd go with the other answers here, but a more cautious "probably" rather than definitely.

Apart from past or present life - there are also the products of life. On the surface - all of that has been pretty much completely destroyed by cosmic radiation. But - could be deposits set down by ancient life below the surface, like our oil and gas and oil shale deposits.

You'd think they must be rare or we would have spotted them on the surface. But on the other hand - cosmic radiation is very damaging. Would there be anything left of a surface oil shale deposit after billions of years?

Every about a thousand fold every 650 million years It's an exponential process. Every 650 million years the remaining organics are reduced in the same proportion. After 1.3 billion years, a thousand tons of amino acids gets reduced to a kilogram, with the rest converted mainly to gases like carbon dioxide, water vapour, methane and ammonia. After 2.6 billion years it's down to a microgram (millionth of a gram) and after 3.9 billion years you are down to less than a picogram (10^-12 grams) of your original thousand tons deposit. And of course this radiation leads to deterioration of the sample making it hard to identify it as life.

Habitability, Taphonomy, and Curiosity's Hunt for Organic Carbon

So, I don't think absence of these deposits on the surface, at least not easy to see from satellites, really shows that they don't exist below the surface. There could be millions of tons of organics from past life ten meters below the surface, and our rovers so far would probably not spot a thing.

That's why Curiosity is currently searching for a recently exposed outcrop in Gale Crater in the hope that it might have exposed ancient organics that haven't yet been destroyed by cosmic radiation.

The organics of course also have to be there in the first place (surely likely to be patchy, in some places more than in others) and buried quickly - if it took several hundred million years to bury them, much of the organics would be gone also.

Oil itself surely not worth the trouble of mining to return to Earth - but if there was some unique biological product on Mars that we don't have on Earth - which you could mine to find - maybe that could be worth returning.

Geologically - well - don't know of anything but again is a unique environment - with the dry ice, low atmospheric pressure, cosmic radiation, things will be different from Earth in some respects. E.g. it's salt deposits are made up of sulfates and perchlorates rather than chlorides as on Earth.

So - not geologically identical in all respects. And different from asteroids also - which don't have those ancient seas deposits you have on Mars or the climate.

But right now, I don’t think we have anything that would be worth returning from Mars except scientific understanding of course. For those who think we could mine gold from Mars (or substitute platinum, or titanium, or whatever you think is especially valuable that you could find on Mars), remember, that you have to do all the work to actually run the gold mine and then send it into orbit. Also the price of gold is going to go down- you are going to need to sell billions of dollars worth of it to make the missions to Mars viable, but what happens to the price of gold if you try to sell billions of dollars of gold to Earth?

And if it is viable from Mars, it’s likely to be viable from other places too, particularly, robotic mining of asteroids may undercut you, and then you’d get less for the price of your gold than you spent out mining it, if robot mining of asteroids costs less. So it has to be competitive with gold mined elsewhere in the solar system, and you have to bear in mind that either

• Prices go down as we mine outside Earth, with large amounts coming from the Moon, asteroids, etc. Some asteroids consist of pure metal and there are ideas for automated robotic mining of them for instance using gas carbonyls
• Or prices are kept artificially high in which case you’d be limited in how much gold (or whatever) you are permitted to sell to Earth in any given year..

I’m not sure it is going to be economically feasible at all, but if it is, I think asteroid mining could easily undercut return of metals from Mars because of the extra delta v need to lift it up from the Mars surface and to send rockets to Mars to pick up the material.