DETERMINATION OF MARTIAN METEORITE LITHOLOGIES AND MINERALOGIES USINGVIBRATIONAL SPECTROSCOPY

We have acquired thermal infrared emission spectra of four Martian met eorite samples, ALH77005, Nakhla, Zagami, and EET79001, representing t hree major lithologies (Iherzolite, clinopyroxenite, and basalt). The spectra of these meteorites are significantly different from each othe r, and we can distinguish the three lithologies easily on the basis of their spectral morphologies. Using a linear deconvolution model, the modal mineralogies of ALH77005, Nakhla, and Zagami were derived from t heir spectra to within 2-19% of the modes derived by optical methods. For Zagami and EET79001, the correct mineral types were identified as present using the linear method, although an exact spectral match usin g available end-member spectra was not obtained, probably due to the l ack of a pigeonite end-member spectrum or shock effects in the meteori tes. The meteorite spectra we have acquired will be used for compariso n with data to be returned by the thermal emission spectrometer (TES) on the Mars Global Surveyor orbiter and would also be useful for compa ring to future rover-or lander-based thermal IR spectra. Based on our results, comparisons of mineral end-member and meteorite spectra with TES spectra of coarse regolith and rocky regions should aid identifica tion and mapping of Martian surface lithologies and unit mineralogy.