HR: 0800h
AN: P11A-0943    [Abstracts]
TI: An experimental crystallization study of a proposed high-Fe low-Al Martian parental liquid
AU: * Filiberto, J
EM: jfiliber@ic.sunysb.edu
AF: SUNY Stony brook, Department of Geosciences SUNY, Stony Brook, NY 11794-2100
AU: Nekvasil, H
EM: hanna.nekvasil@sunysb.edu
AF: SUNY Stony brook, Department of Geosciences SUNY, Stony Brook, NY 11794-2100
AU: Lindsley, D H
EM: Donald.Lindsley@sunysb.edu
AF: SUNY Stony brook, Department of Geosciences SUNY, Stony Brook, NY 11794-2100
AB: Recent work has started to question the validity of the assumption of high-Fe, low-Al Martian magma compositions as parental to the SNC meteorites, in particular to the Chassigny meteorite. Minitti and Rutherford (2000 GCA Vol. 64) performed experiments on Johnson et al.'s (1991 GCA vol. 55) A* composition at low pressure and did not produce the assemblage of any of the SNC meteorites. In contrast, the crystallizing assemblages of hawaiite with greater the 0.4 wt% water and pressures above 4.3 kbar has been shown to replicate well the Chassigny assemblages (Nekvasil et al. 2004 LPSC 35). Experiments were conducted to investigate whether similar results could be obtained by a low-Al, high-Fe magma crystallizing at higher pressures and water contents than used in earlier work. The Chassigny cumulate assemblage is dominantly olivine with minor cpx, low-Ca pyroxene, and chromite. The polyphase melt inclusions contained within the olivine contain augite, low-Ca pyroxene, kaersutite, apatite, Ti-biotite, chrome rich spinel, and a feldspar glass. In contrast, Minitti and Rutherford's (2000 GCA Vol. 64) experimentally obtained low pressure assemblage for the A* composition of Johnson et al. (1991 GCA vol. 55) is olivine, sub-calcic augite, pigeonite, Ti-magnetite, ilmenite, and plagioclase. Our experimental results indicate that at 4.3 kbar, in the presence of water (0.2 wt% bulk water), the assemblage is pigeonite-dominated with olivine, plagioclase, and ilmenite as additional crystallizing phases. At 9.3 kbar the assemblage continues to be pigeonite dominated, with olivine, and plagioclase. Ongoing experiments are evaluating the direct role of water in affecting the mineral assemblages. These assemblages at 0.2 wt% water do not produce the cumulate assemblage seen in the Chassigny meteorite. Furthermore, since they do not contain kaersutite, apatite, biotite, or low-Ca pyroxene, they differ markedly from the melt-inclusion assemblages of the Chassigny meteorite. Thus, to date no experiments on any high-Fe, low-Al parental liquid have produced the Chassigny mineral assemblages.
DE: 5410 Composition
DE: 3346 Planetary meteorology (5445, 5739)
DE: 3362 Stratosphere/troposphere interactions
DE: 3630 Experimental mineralogy and petrology
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting