Lunar and Planetary Science XXXI sess06.pdf

Monday, March 13, 2000 MARTIAN METEORITES II 2:30 p.m. Room A

Chairs: T. L. Grove R. C. F. Lentz

Dann J. C. Holzheid A. H. Grove T. L. McSween H. Y. Jr. Phase Equilibria of the Shergotty Meteorite: New Petrologic Constraints on the H2O Content of Martian Magmas [#1081] The augite + pigeonite assemblage in Shergotty is most closely reproduced in 200 MPa H2O-saturated experiments and implies pre-eruptive H2O contents af about 6 wt. %.

Lentz R. C. F. * Ryan J. G. Riciputi L. R. McSween H. Y. Jr. Water in the Martian Mantle: Clues from Light Lithophile Elements in Martian Meteorites [#1672] SIMS data of B, Be and Li in nakhlites and Shergotty are used to examine the volatile histories of martian parental magmas. Significant loss of B and Li in Shergotty during crystallization points to a wet parent magma.

Dyar M. D. * Delaney J. S. Kinny P. D. Graham C. M. Implications of Dehydrogenation Processes in Amphibole for Planetary Oxygen and Hydrogen Budgets [#1768] Interrelationships among D/H, H, and ferric iron contents in amphibole, measured at microscales of 10 × 15 µm, are examined, with emphasis on the understanding dehydrogenation processes.

Boctor N. Z. * Alexander C. M. O’D. Wang J. Hauri E. Hydrogen Isotope Studies of Mafic, Feldspathic, and Melt Inclusion Glasses in Martian Meteorite Allan Hills 77005 [#1759] Shock produced mafic (δD=1301-3031 ‰) and feldspathic glasses (δD=1821-2536 ‰) in ALH77005 have much higher δD compositions and water contents than melt inclusions in olivines (-18 ‰ to 304 ‰).

Farquhar J. * Savarino J. Jackson T. L. Thiemens M. H. Evidence of Atmospheric Sulfur in SNC Meteorites: Implications for the Martian Sulfur Cycle [#1275] We present S-isotope data for oxidized and reduced phases in SNC meteorites and discuss implications for the Martian S-cycle. S-isotope data reflect atmospheric deposition of oxidized species, followed by incorporation and mobilization within the regolith.

Wentworth S. J. * Thomas-Keprta K. L. McKay D. S. Weathering and Secondary Minerals in the Martian Meteorite Shergotty [#1888] The Shergotty martian meteorite contains weathering features and secondary minerals much like those in Nakhla, including secondary silicates, NaCl, and Ca-sulfate. It is likely that the weathering occurred on Mars.

Bridges J. C. * Smith M. P. Grady M. M. Progressive Evaporation and Relict Fluid Inclusions in the Nakhlites [#1590] A model for the progressive evaporation of brine within the nakhlite parent rocks is described. This can account for the variation in salt assemblages between the 3 meteorites. Fluid inclusion studies are also reported.