Evidence of refractory organic matter preserved in the mudstones of Yellowknife Bay and the Murray Formations

Wednesday, 16 December 2015: 09:45
3014 (Moscone West)
Jennifer L Eigenbrode1, Andrew Steele2, Roger E Summons3, Brad Sutter4, Amy McAdam1, Heather B. Franz5, Paul R Mahaffy1, Pamela Gales Conrad1, Caroline Freissinet6, Daniel Patrick Glavin1, Maeva Millan7 and Douglas W Ming8, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)Carnegie Institution for Science Washington, Washington, DC, United States, (3)MIT Lincoln Laboratory, Lexington, MA, United States, (4)Jacobs Technology, NASA Johnson Space Center, Houston, TX, United States, (5)NASA Goddard Space Flight Center, Center for Research and Exploration in Space Science and Technology, Greenbelt, MD, United States, (6)NASA Goddard Space Flight Center, NASA Postdoctoral Program, Greenbelt, MD, United States, (7)LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales, Paris Cedex 05, France, (8)NASA Johnson Space Center, Houston, TX, United States
Volatiles from high-temperature (above 500°C) pyrolysis of drilled and sieved deltaic/lacustrine mudstones at Yellowknife Bay and Pahrump Hills were detected by the Sample Analysis at Mars (SAM) instrument’s evolved gas analysis experiment onboard the Curiosity rover in Gale Crater, Mars. Mass fragments detected from the mudstones are consistent with C1-C4 alkyl and single-ring aromatic components that evolve at different temperatures and often in multiple phases. Concurrent release of oxidized sulfur (sulfur dioxide and sulfur trioxide), sulfide gases (hydrogen sulfide, carbonyl sulfide, carbon disulfide, dimethylsulfide or thiol, and thiophene) suggest that either these gases are evolving directly from the mudstone or are products of gas phase reactions in the SAM oven, or both. Multiple chlorohydrocarbon releases are also observed in analysis of the Mojave mudstone indicating punctuated organic releases from the sample. The organic signatures observed are unique to specific samples and are not observed in blanks or all samples, nor can the SAM background explain them. These results suggest that geologically refractory organic matter has been preserved in some Hesperian mudstones despite possible acid-sulfate weathering (as suggested by jarosite in Mojave) and exposure to ionizing cosmic rays after exhumation. We will report on ongoing study of these samples.