Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at ~ 40 - 50 GPa and their Relevance to the Martian Reolith Component Present in Shergotties

Conference · Wed Mar 14 04:00:00 EDT 2012

OSTI ID:1036318

Rao, M N; Nyquist, L E; Ross, D K; Asimow, P D; See, T; Sutton, S; Cardernas, F; Montes, R; Cintala, M ^[1]

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1. NASA-JSC

Basaltic shergottites such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in Martian atmospheric gases and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a Martian regolith component based on Sm and Kr isotopic studies. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in Martian meteorites. The material comprising these glasses arises from the highly oxidizing Martian surface and sulfur is unlikely to occur as sulfide in the Martian regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the Martian meteorites into space. As a result of high energy deposition by shock (~ 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H₂ and CO which were shock-implanted from the Martian atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to shock pressures between 40 and 50 GPa under reducing conditions. The experimental products from the recovered samples were analyzed by SEM and microprobe techniques at JSC.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 1036318
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

58 GEOSCIENCES
BASALT
BEARINGS
COLUMBIA RIVER
GASES
GEOPHYSICS
GLASS
IRON SULFATES
IRON SULFIDES
METEORITES
METEOROIDS
MIXTURES
ORIGIN
QUENCHING
RARE GASES
REDUCING AGENTS
SIMULATION
SULFATES
SULFIDES
SULFUR