Indiana University Bloomington

Lisa M. Pratt

Lisa M. Pratt

Provost Professor of Geological Sciences


Office:   MSBII 416
Phone:   812-855-9203

Educational Background

  • Ph.D., 1982, Geology, Princeton University
  • M.S., 1978, Geology, University of North Carolina
  • M.S., 1974, Botany, University of Illinois
  • B.A., 1972, Botany, University of North Carolina

Research Interests

Geomicrobiology of sulfate-reducing microorganisms

Biotic and abiotic fractionation of sulfur isotopes in modern and ancient oceans and lakes

Influence of wildfire on carbon isotopic excursions during the Cretaceous

Fate of complex organic molecules on the surface of Mars

Research Focus Site

Courses Recently Taught

  • G105, Earth: Our Habitable Planet
  • G334, Sedimentology and Stratigraphy
  • G583, Isotope Geochemistry
  • G690, Geomicrobiology
  • G690, Advanced Terrestrial Stratigraphy

Research Philosophy

The tradition in my research group is for students to learn through field and laboratory experiences involving ever-increasing levels of independence. My research group includes undergraduates, graduate students, and post-doctoral researchers who work closely together to ensure the maintenance and calibration of instruments including gas chromatographs, ion chromatographs, and mass spectrometers. I am fortunate to be assisted by Ruth Droppo in graphic design, Jon Fong in analytical chemistry, and Ben Underwoodin stable isotope mass spectrometry. These students and staff are the foundation of my scientific reputation. Every paper that I publish and every grant that I submit are a reflection of the people at Indiana University who work with me.

Recent Research Projects

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Shallow-Borehole Array for Measuring Greenland Emission of Trace Gases as an Analogue for Methane on Mars (GETGAMM) 20011-2016. GETGAMM website

Previous funding from the National Science Foundation and the NASA Astrobiology Institute support our studies of sulfur isotopic compositions of sulfide and sulfate in water samples collected at depths of 1 to 4 kilometers below the surface from gold mines in South Africa and the Canadian Arctic. Isotopic data are used to determine rates of microbial sulfate reduction and microbial sulfide oxidation in the deep subsurface. Combined with genomic data from collaborating microbiologists, sulfur isotopic data are evidence of an active deep-Earth microbial community. Pratt is Director of the NASA Astrobiology Lead Team entitled Biosustainable Energy and Nutrient Cycles in the Deep Subsurface of Earth and Mars.

With previous funding from the David and Lucille Packard Foundation, my research group has studied alkaline- and salt-tolerant bacteria and archaea in shallow lakes on the Oregon Basalt Plateau. Pratt (Geological Sciences) and Bauer (Biochemistry) collaborate on a project entitled Life at the Edge of Hydration. Results of field and laboratory experiments are used to assess dessication limits for microbial life on Earth and to evaluate the pathways for origination of life on a planetary body like Mars with severe water limitation.

Graduate Student Projects

Cindy Elbaz (Ph.D. 2015) "Microbial cycling of sulfur in a mesothermal spring on the Oregon Basalt Plateau."

Humberto Carvajal-Ortiz (Ph.D. 2013) "Stable isotopes of carbon, hydrogen, and sulfur in clathrates containing methane and hydrogen sulfide as potential biosignatures on icy planetary bodies"

Sarah Cadieux (Ph.D. Geological Sciences)

Kevin Webster (Ph.D. Geological Sciences)

Walter Gray (M.S., 2012) "Refined stratigraphic interpretation of the St. Louis Limestone, south-central Indiana, USA, using sulfur isotopic curves for carbonate-associated sulfate" Document URL

Undergraduate Student Projects

Jonathan Bell "Ferrous/ferric iron ratios in pore water from coal refuse associated with acid mine drainage in Indiana"

Dalton Hardisty "Seasonal variation in budget and chemistry of pore water in a coal refuse deposit in southwestern Indiana"

Recent Publications

Carvajal-Ortiz, H and Pratt, L.M. (2013) Influences of salinity and temperature on the stable isotopic composition of methane and hydrogen sulfide trapped in pressure-vessel hydrates. Geochimica et Cosmochimica Acta, 118, 72-84. DOI

Carvajal-Ortiz, H and Pratt, L.M. (2013) Effects of clay minerals and biosurfactants on isotopic and molecular characteristics of methane encaged in pressure vessel gas hydrates. Organic Geochemistry, 60, 83-92. DOI

Young, S.A., Loukola-Ruskeeniemi, K., and Pratt, L.M. (2013) Reactions of hydrothermal solutions with organic matter in Paleoproterozoic black shales at Talvivaara, Finland: Evidence from multiple sulfur isotopes. Earth and Planetary Science Letters, 367, 1-14. DOI

Hardisty, D.S., Olyphant, G.A., Belle, J.B. Johnson, A.P., and Pratt, L.M. (2013) Acidophilic sulfur disproportionation.Geochimica et Cosmochimica Acta, 113, 136-151. DOI

Szynkiewicz, A., Johnson, A.P., and Pratt, L.M. (2012) Sulfur species and biosignatures in Sulphur Springs, Valles Caldera, New Mexico-Implications for Mars astrobiology. Earth and Planetary Science Letters, 321, 1-13, DOI

Silver, B.J., Raymond, R., Sigman, D.M., Prokopeko, M., Lollar, B.S., Lacrampe-Couloume, G., Fogel, M.L., Pratt, L.M., Lefticariu, L., and Onstott, T.C. (2012) The origin of NO3 and N2 in deep subsurface fracture water of South Africa. Chemical Geology, 294, 51-62. DOI

Johnson, A. and Pratt, L.M. (2010) Metal Catalyzed Degradation and Racemization of Amino Acids in Iron Sulfate Brines under Simulated Martian Surface Conditions. Icarus 207, 124-132.

Szynkiewicz, A., Ewing, R.C., Moore, C.H., Glamoclija, M. B., Bustos, D, and Pratt, L.M. (2010) Origin of terrestrial gypsum dunes: Implications for Martian gypsum-rich dunes of Olympia Undae. Geomorpholgy, v. 121, p. 69-83.

Johnson, A.P. and Pratt, L.M. (2010) Metal-catalyzed degradation and racemization of amino acids in iron sulfate brines under simulated martian surface conditions. ICARUS, v. 207, p. 124-132.

Pratt, L.M., Allen, C., Allwood, A., Anbar, A., Atreya, S., Carr, M. Des Marais, D., Grant, J., Glavin, D., Hamilton, V., Herkenhoff, K., Hipkin, V., Lollar, B.S., McCollom, T., McEwen, A., McLennan, S., Milliken, R., Ming, D., Ori, G.G., Parnell, J., Poulet, F., and Westall, F. (2010) Mars Astrobiology Explorer-Cacher (MAX-C): A Potential Rover Mission for 2018. Astrobiology, v. 10, p. 127-163.

Finkelstein, D.B., Brassell, S.C.and Pratt, L.M. (2010) Microbial biosynthesis of wax esters during desiccation: Adaptation for colonization of the earliest terrestrial environments? Geology, 38, 247-250.

Szynkiewicz, A., Moore, C.H., Glamoclija, M., and Pratt, L.M. (2009) Sulfur isotope signatures in gypsiferous sediments of the Estancia and Tularosa Basins as indicators of sulfate sources, hydrological processes, and microbial activity, Geochimica et Cosmochimica Acta, 73, 6162-6186

Pratt, L.M., C. Allen, A.C. Allwood, A. Anbar, S.K. Atreya, D.W. Beaty, M.H. Carr, J.A. Crisp, D.J. Des Marais, J.A. Grant, D.P. Glavin, V.E. Hamilton, K. Herkenhoff, V. Hipkin, B. Sherwood Lollar, T.M., McCollom, A.S. McEwen, S.M. McLennan, R.E. Milliken, D.W. Ming, G.G. Ori, J. Parnell, F. Poulet, C.G. Salvo, F. Westall, C.W. Whetsel, and M.G. Wilson (2009) Mars Astrobiology Explorer-Cacher: A potential rover mission for 2018, Final report from the Mid-Range Rover Science Analysis Group (MRR-SAG), 94 pp.. Mars Exploration Program Analysis Group (MEPAG) at

Ries, J. B., Fike, D.A., Pratt, L.M., Lyons, T.W., and Grotzinger, J.P., 2009, Superheavy pyrite (δ34Spyr > δ14S CAS) in the terminal Proterozoic Nama Group, southern Namibia: A consequence of low seawater sulfate at the dawn of animal life. Geology, 37, 743-746.

Davidson, M.M., Onstott, T.C., Bisher, M.E., Pratt, L.M., Fong, J., Southam, G., and Pfiffner, S. (2009) Sulfur Isotope Enrichment during Maintenance Metabolism in the Thermophilic Sulfate-Reducing Bacterium Desulfotomaculum putei. Applied and Environmental Microbiology.

West, L., McGown, D.J., Onstott, T.C., Morris, R.V., Suchecki, P., and Pratt, L.M. (2009) High Lake gossan deposit: An Arctic analogue for ancient Martian surficial processes? Planetary and Space Science, 57, 1302-1311.

Recent Awards and Honors

Provost Professorship, October 2009
Phi Beta Kappa Visiting Scholar, 2009-2010
Indiana University College of Arts and Sciences Alumni, Distinguished Faculty Member, 2003
American Association Petroleum Geologists, Eastern Section, Outstanding Educator, 2002

Current Service

Member NASA Science Advisory Group on Science Priorities for Mars Sample Return (2007-2012).
Member NASA Science Advisory Group for Mars Strategic Science for the Decade (2007-2012).
Member NASA Planetary Science Subcommittee of Advisory Board (2008-2011)

Canadian Research Chairs Program College of Reviews, 2004-2005

Laboratory Facilities

The Stable Isotope Research Facility at Indiana University (SIRF-Indiana) is located in the Department of Geological Sciences and is directed by Professors Lisa Pratt and Edward Ripley. SIRF-Indiana has three stable isotope mass spectrometers and is one of the few laboratories in the U.S. with a modern isotope mass spectrometer (Finnigan MAT 252) dedicated to running sulfur samples. The SIRF sulfur instrument has an elemental analyzer (EA) inlet that is well calibrated for samples containing between 0.1 and 1 micromole of sulfur in the form of BaSO4 and Ag2S. Our reputation for accuracy and precision of sulfur isotope measurements is validated by numerous requests for access to SIRF mass spectrometers. The institutional affiliation of our collaborations and contracts for δ34S data over the past several years is as follows: Northwestern University, Princeton University, California Institute of Technology, Max Planck Institute for Marine Microbiology (Germany), Odense University (Denmark), Harvard University, Massachusetts Institute of Technology, NASA Ames, Carnegie Geophysical Laboratory, Kanazawa University (Japan), Pennsylvania State University, and University of Tennessee. In addition to routine δ34S measurements, Ripley and Pratt are collaborating on the design and calibration of a laser-assisted fluorination chamber for determination of δ33S and δ36S on samples of Ag2S converted to SF6.