Presence and detection of carbonates on the Martian surface

The messages we receive from Mars about the presence of carbonates are quit e contradictory. On the one hand, images of the planet clearly show the sig natures of past bodies of standing water, where the accumulation of sedimen tary deposits should have occurred. On the other hand, the apparent absence of carbonates in the homogeneous fines covering the Martian surface raises the question: where could carbonates hide now? In this paper we discuss th e subject and demonstrate that a proposed destruction mechanism, the photod ecomposition caused by UV radiation, cannot account alone for the "missing" carbonates. By means of simulations we show that the difficulties in detec ting the carbonates can be ascribed to the low temperatures of the emitting zones, observed up to now. Finally, we derive the minimum amount of such m inerals that could possibly be detected in future observations of Mars, and we compare the results of simulations with observed spectra.