• journal_title：American Mineralogist
• Contributor：D.C. Golden ; Douglas W. Ming ; Craig S. Schwandt ; Howard V. Lauer ; Jr. ; Richard A. Socki ; Richard V. Morris ; Gary E. Lofgren ; Gordon A. McKay
• Publisher：Mineralogical Society of America
• Date：2001-
• Format：text/html
• Language：en
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：86
• issue：3
• firstpage：370
• section：Letters

We show experimental evidence that the zoned Mg-Fe-Ca carbonates, magnetite, and Fe sulfides in Martian meteorite ALH84001 may have formed by simple, inorganic processes. Chemically zoned carbonate globules and Fe sulfides were rapidly precipitated under low-temperature (150 °C), hydrothermal, and non-equilibrium conditions from multiple fluxes of Ca-Mg-Fe-CO₂-S-H₂O solutions that have different compositions. Chemically pure, single-domain, defect-free magnetite crystals were formed by subsequent decomposition of previously precipitated Fe-rich carbonates by brief heating to 470 °C. The sequence of hydrothermal precipitation of carbonates from flowing CO₂-rich waters followed by a transient thermal event provides an inorganic explanation for the formation of the carbonate globules, magnetite, and Fe sulfides in ALH84001. In separate experiments, kinetically controlled ¹³C enrichment was observed in synthetic carbonates that is similar in magnitude to the ¹³C enrichment in ALH84001 carbonates.