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Mineralogical, chemical, organic and microbial properties of subsurface soil cores from Mars Desert Research Station (Utah, USA): Phyllosilicate and sulfate analogues to Mars mission landing sites

Research output: Contribution to journalArticle

  • Carol R. Stoker
  • Jonathan Clarke
  • Susana O. L. Direito
  • David Blake
  • Kevin R. Martin
  • Jhony Zavaleta
  • Bernard Foing
Original languageEnglish
Pages (from-to)269-289
Number of pages21
JournalInternational Journal of Astrobiology
Volume10
Issue number3
DOIs
Publication statusPublished - Jul 2011
Externally publishedYes

Abstract

We collected and analysed soil cores from four geologic units surrounding Mars Desert Research Station (MDRS) Utah, USA, including Mancos Shale, Dakota Sandstone, Morrison formation (Brushy Basin member) and Summerville formation. The area is an important geochemical and morphological analogue to terrains on Mars. Soils were analysed for mineralogy by a Terra X-ray diffractometer (XRD), a field version of the CheMin instrument on the Mars Science Laboratory (MSL) mission (2012 landing). Soluble ion chemistry, total organic content and identity and distribution of microbial populations were also determined. The Terra data reveal that Mancos and Morrison soils are rich in phyllosilicates similar to those observed on Mars from orbital measurements (montmorillonite, nontronite and illite). Evaporite minerals observed include gypsum, thenardite, polyhalite and calcite. Soil chemical analysis shows sulfate the dominant anion in all soils and SO(4)>>CO(3), as on Mars. The cation pattern Na>Ca>Mg is seen in all soils except for the Summerville where Ca>Na. In all soils, SO(4) correlates with Na, suggesting sodium sulfates are the dominant phase. Oxidizable organics are low in all soils and range from a high of 0.7% in the Mancos samples to undetectable at a detection limit of 0.1% in the Morrison soils. Minerals rich in chromium and vanadium were identified in Morrison soils that result from diagenetic replacement of organic compounds. Depositional environment, geologic history and mineralogy all affect the ability to preserve and detect organic compounds. Subsurface biosphere populations were revealed to contain organisms from all three domains (Archaea, Bacteria and Eukarya) with cell density between 3.0x10(6) and 1.8x10(7) cells ml(-1) at the deepest depth. These measurements are analogous to data that could be obtained on future robotic or human Mars missions and results are relevant to the MSL mission that will investigate phyllosilicates on Mars. Received 20 December 2010, accepted 23 February 2011, first published online 8 April 2011

    Research areas

  • Mars Science Lander, CheMin instrument, Mars Analogue, MDRS Utah, clay minerals, organics, subsurface biology, GRADIENT GEL-ELECTROPHORESIS, 16S RIBOSOMAL-RNA, MERIDIANI-PLANUM, MANCOS SHALE, MORRISON FORMATION, FORELAND-BASIN, SOUTHERN UTAH, SURFACE, HEMATITE, COLORADO

ID: 21875311