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View Diary: NASA Scientists: Earthshaking Discovery On Mars (355 comments)

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  •  fossils (7+ / 0-)

    Maybe you should expand your idea of fossils. Grotzinger says this is in a powerpoint presentation conducted before landing:

    On Mars, how might have early preservation of organic matter and/or delicate textures proceeded?

    - Hematite, other iron oxides, sulfate minerals, phyllosilicate minerals, silica and possible chloride minerals have all been suggested as possible substrates for fossil preservation.

    - Indeed, all are known to facilitate the preservation of organic molecules on Earth. Some iron oxides, sulfate salts additionally can preserve isotopic signatures of biogeochemical processes.

    How high is the fossil preservation potential?

    - The goal here is to evaluate what mineral(s) may have precipitated early, or other processes such as clay mineral adsorption, would have caused entrapment of organic compounds and/or preservation of biogenic textures.

    - Ideal example: Precipitation of mineral at low temperature that impregnated cellular structure to entomb organics, mineral aggregate has such low permeability that oxidation... is excluded.

    Note that SAM's tunable laser spectrometer can determine isotope ratios of N, H, O, S, etc. I wonder if something like unusual carbon isotope ratios have been found, pointing to a possible biotic cause.

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