Materials perspective
What's the stability of carbonate minerals over billions of years of exposure to near-vacuum conditions and high UV bombardment?
I ask because materials are never static, they just have degrees of stability - it was a key lesson in my corrosion projects. Everything corrodes - i.e., experiences environmentally induced degradation. Iron, concrete, aluminum, plastics all have their differing forms of environmental degradation. The same goes for rocks. Zircons weather well and tell use about the dawn of Earth but may be mechanically reduced to little specks in igneous and metamorphic rocks. Meanwhile, carbonate minerals in Earth's aggressive environment erode, chemically alter, and redeposit on timescales of human history.
Mars is a much less aggressive environment, but it's not necessarily one to guarantee carbonate minerals will stay in place for 3.8 billion years. Do the studies regularly address that potential weathering?