Accession Number N20130003564
Title Water in Nominally Anhydrous Minerals from Nakhlites and Shergottites.
Publication Date 2013
Media Count 2p
Personal Author A. H. Peslier
Abstract Estimating the amount of water in the interior of terrestrial planets has tremendous implications on our understanding of solar nebula evolution, planet formation and geological history, and extraterrestrial volcanism. Mars has been a recent focus of such enquiry with complementary datasets from spacecrafts, rovers and martian meteorite studies. In planetary interiors, water can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) such as olivine, pyroxene, or feldspar (1-3). Measuring water in Martian meteorite NAM is challenging because the minerals are fragile and riddled with fractures from impact processes that makes them break apart during sample processing. Moreover, curing the sample in epoxy causes problems for the two main water analysis techniques, Fourier transform infrared spectrometry (FTIR) and secondary ionization mass spectrometry (SIMS). Measurements to date have resulted in a heated debate on how much water the mantle of Mars contains. SIMS studies of NAM (4), amphiboles (5), and apatites (6-8) from Martian meteorites report finding enough water in these phases to infer that the martian mantle is as hydrous as that of the Earth. On the other hand, a SIMS study of glass in olivine melt inclusions from shergottites concludes that the Martian mantle is much drier (9). The latter interpretation is also supported by the fact that most martian hydrous minerals generally have the relevant sites filled with Cl and F instead of H (10,11). As for experimental results, martian basalt compositions can be reproduced using water as well as Cl in the parent melts (12,13). Here FTIR is used to measure water in martian meteorite minerals in order to constrain the origin of the distribution of water in martian meteorite phases.
Keywords Calcium phosphates
Mars surface
Planetary cores
Planetary evolution
Planetary structure

Source Agency National Aeronautics and Space Administration
NTIS Subject Category 54A - Astrogeology
84B - Extraterrestrial Exploration
Corporate Author National Aeronautics and Space Administration, Houston, TX. Lyndon B. Johnson Space Center.
Document Type Conference proceedings
Title Note N/A
NTIS Issue Number 1319
Contract Number N/A

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