Humans with a level of technology roughly equal to the present day, not more than a decade or two more advanced (e.g. they might have slightly more efficient rockets, or a more miniaturized comm system, but no stargates, warp drive, or lightsabers), found a colony on the surface of Mars. Assume a somewhat stereotypical settlement infrastructure with landing pad, living habitat, hydroponic farm, research lab, etc., for anywhere from a dozen to a few dozen colonists. For some reason (because plot), the colony is abandoned (all of the people leave or die) while it is in working condition, and the colony site is then not visited by any life form for an arbitrary length of time (e.g. hundreds or even thousands of years).
How long would it take for the colony to become an unidentifiable, or barely identifiable, pile of rubble? We have a lot of archaeological data on how long stuff lasts on Earth before being effectively returned to nature, but would these measurements apply on Mars? As Mars has an active weather system (unlike the Moon), I expect that there will be significant erosion effects, but I doubt that the rate would be the same as on Earth. Would the colony last a hundred years? A thousand? Ten thousand? A million? A hundred million?
For the purposes of this question, "unidentifiable" means that the physical infrastructure has effectively returned to nature. Some remnants (e.g. scraps of metal, pieces of plastic, a screw or bolt here and there) can remain that testify to prior inhabitation of or at least visits to the area, but determining what those parts were from (e.g. telling that this aluminum board was from a Standard 12 Person Habitat (TM) manufactured by SpaceCo in 2022 as opposed to just knowing that it was probably built by humans or possibly another civilization at some point in time) would require at least a significant archaeological expedition and research project, not a casual glance.
Feel free to make any reasonable assumptions (if any) necessary to answer or simplify the problem by comparison with similar components whose properties are well-known (e.g. "If the colony was more or less a bunch of Apollo capsules welded together, based on what we know of their construction, the answer would be....")