Iron-Rich Carbonates as the Potential Source of Evolved CO2 Detected by the Sample Analysis at Mars (SAM) Instrument in Gale Crater

Stern, J. C.
Mertzman, S.
Rampe, E. B.
Mahaffy, P. R.
Eigenbrode, J. L.
Heil, E.
Morris, R. V.
McAdam, A. C.
Franz, H. B.
Sutter, B.
Archer, P. D.
Navarro-Gonzalez, R.
Glavin, D. P.
Niles, P. B.
Ming, D. W.

Publication date

December 2015

Abstract

The Sample Analysis at Mars (SAM) instrument detected at least 4 distinct CO2 release during the pyrolysis of a sample scooped from the Rocknest (RN) eolian deposit. The highest peak CO2 release temperature (478-502 C) has been attributed to either a Fe-rich carbonate or nano-phase Mg-carbonate. The objective of this experimental study was to evaluate the thermal evolved gas analysis (T/EGA) characteristics of a series of terrestrial Fe-rich carbonates under analog SAM operating conditions to compare with the RN CO2 releases. Natural Fe-rich carbonates (<53 microns) with varying Fe amounts (Fe(0.66)X(0.34)- to Fe(0.99)X(0.01)-CO3, where X refers to Mg and/or Mn) were selected for T/EGA. The carbonates were heated from 25 to 715 C (35 C/min)...