Carbonates and coated particles on Mars

The identification of carbonate deposits on Mars may be extremely useful fo r understanding the paleoclimate of the planet and may have very important implications on the search for extinct Martian life, owing to the high pote ntial of carbonates to record traces of fossils. In this work, we present s ome results on the possible presence and detectability of coated particles produced by the photodecomposition of the outer layer of carbonate grains. Our results suggest that the photodecomposition process, if really effectiv e in the Martian environment, should not necessarily prevent the detection of relatively large carbonate particles on the surface and in the atmospher ic aerosol of Mars. The detection of carbonates is obviously more likely in particular sites of the Martian surface where geomorphological indications seem to suggest the past existence of bodies of water in which carbonate p recipitation could have occurred. A list of these areas is also given. (C) 2000 Elsevier Science Ltd. All rights reserved.