Geological Society of America

T342 Basalt Weathering on Earth and Mars

Wednesday, 25 October 2017
1:30 PM - 5:30 PM
Tahoma 1

INVESTIGATING THE EFFECTS OF CHLORINE MINERALS ON HYDROGEN SULFIDE FORMATION FROM SULFUR MINERALS DURING EVOLVED GAS ANALYSIS (EGA) TO CONSTRAIN MARTIAN BASALTIC MINERALOGY

Paper number: T342-6
Program: Technical Sessions
Time: 2:45 PM – 3:00 PM

Authors

Gregory M. Wong Presenting Author
The Pennsylvania State University, University Park, PA
Amy McAdam
NASA Goddard Space Flight Center, Greenbelt, MD
Jennifer L. Eigenbrode
NASA Goddard Space Flight Center, Greenbelt, MD
James M.T. Lewis
NASA Goddard Space Flight Center, Greenbelt, MD
James M.T. Lewis
Columbia, MD
Christopher H. House
The Pennsylvania State University, University Park, PA

Abstract

The Mars Science Laboratory (MSL) has detected basaltic materials in Gale Crater, Mars. Analysis of these materials by the Sample Analysis at Mars (SAM) by evolved gas analysis-mass spectrometry (EGA-MS) has shown the presence of both oxidized sulfur (SO₂) and reduced sulfur (H₂S) gases. It has been suggested that the observed H₂S indicates the presence of sulfide minerals in the sample, either primary sulfides from physically weathered basalt or secondary sulfides. To constrain the possible sources of evolved H₂S in EGA-MS, we have conducted laboratory experiments using EGA-MS under SAM-like conditions. These experiments investigated the complex chemistry imposed by mineral mixtures in the SAM oven that may be responsible for martian observations.

Previous laboratory experiments examined two-component mixtures with either a sulfate or sulfide mixed with a chloride or oxychlorine phase. These mixtures were analyzed using a Frontier PY-3030 pyrolyzer operated at 30 mbar He and attached to an Agilent 5975T-LTM MS. In general, the sulfur-chlorine mixtures demonstrated an increase in the amount of evolved H₂S compared to the respective sulfur minerals alone. Interestingly, these preliminary results indicated that the calcium perchlorate mixtures evolved up to approximately 17 times as much H₂S as the sulfur minerals on their own. The calcium perchlorate mixtures demonstrated an overall greater effect on H₂S production than the other mixtures. Additional experiments with sulfur minerals mixed with various oxychlorine phases (e.g. Ca, Fe, Mg perchlorates) are being conducted to understand the enhanced H₂S release. Given the widespread presence of perchlorates and sulfur minerals on Mars, it is critical to understand how these phases will interact during EGA-MS in order to understand aspects of martian mineralogy inaccessible by other instruments on board MSL.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-304509

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