Low-temperature carbonate concretions in the martian meteorite ALH84001: Evidence from stable isotopes and mineralogy

Journal Article · Fri Mar 14 04:00:00 EST 1997 · Science

DOI:https://doi.org/10.1126/science.275.5306.1633· OSTI ID:468974

Valley, J W ^[1]; Eiler, J M; Stolper, E M ^[2]

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1. Univ. of Wisconsin, Madison, WI (United States)
2. California Institute of Technology, Pasadena, CA (United States); and others

The martian meteorite ALH84001 contains small, disk-shaped concentrations of carbonate with concentric chemical and mineralogical zonation. Oxygen isotope compositions of these concretions, measured by ion microprobe, range from {delta}{sup 18}O = +9.5 to +20.5{per_thousand}. Most of the core of one concretion is homogeneous (16.7 {+-} 1.2{per_thousand}) and over 5{per_thousand} higher in ({delta}{sup 18}O = 4.6 {+-} 1.2{per_thousand}). Secondary SiO{sub 2} has {delta}{sup 18}O = 20.4{per_thousand}. Carbon isotope ratios measured from the core of one concretion average {delta}{sup 13}C = 46 {+-} 8{per_thousand}, consistent with formation on Mars. The isotopic variations and mineral compositions offer no evidence for high temperature (>650{degrees}C) carbonate precipitation and suggest non-equilibrium processes at low temperatures (<{approximately} 300{degrees}C). 44 refs., 3 figs., 1 tab.

• OSTI ID: 468974
• Journal Information: Science, Journal Name: Science Journal Issue: 5306 Vol. 275; ISSN SCIEAS; ISSN 0036-8075
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
MARS PLANET
METEORITES
MINERALOGY