Scott M. McLennan
B.Sc.(Hon), University of Western Ontario, 1975
Visiting Fellow, Australian National University, 1989, 1994
Preserved within sedimentary rocks is a record of planetary history. At any time eroding sediments are providing a sampling of the exposed crust and are being influenced by the contemporaneous climate. Using sedimentary compositions, it is possible to evaluate the tectonic, climatic and geographic conditions under which a sedimentary rock was deposited. Since sediments are present throughout much of the geological histories of both Earth and Mars, it is possible to trace the evolution of the surfaces of these planets. For Mars, no sedimentary materials are yet available for laboratory analysis and accordingly, an alternative approach to studying the Martian sedimentary rock cycle is through laboratory experiments that simulate sedimentary conditions on Mars.
The interests of Professor McLennan lie in evaluating the evolution of planetary crusts and surficial processes using the chemical composition of sedimentary rocks and laboratory experiments that simulate a variety of sedimentary processes. It is now clear that there have been active sedimentary environments operating on Mars, especially early in its history and Professor McLennan is also involved with evaluating the chemical and mineralogical composition of Martian surface materials in terms of sedimentary provenance, sedimentary processes, and crustal evolution.
Recent research projects include the following:
1. Mars Mission Support and Research
Professor McLennan is a member of the science teams for the 2003 Mars Exploration Rover mission (Opportunity) and the 2011 Mars Science Laboratory mission (Curiosity). His role is to support mission planning and operations and to carry out research using the most recently returned data from Mars. He is also on two instrument teams (PIXL and SuperCam) for the upcoming Mars2020 rover mission and is part of the science team for the proposed SCIM Mars dust sample return mission that is being developed by the BoldlyGo Institute, a not-for-profit private enterprise. Professor McLennan was a participating scientist on the 2001 Mars Odyssey Gamma Ray Spectrometer experiment until that instrument stopped collecting useful data in 2008. He has supervised a number student and post-doctoral collaborators on these missions.
2. Sedimentary Geochemistry on Mars
Chemical analyses of surface rocks and soils returned during the Viking, Pathfinder, Spirit, Opportunity, Phoenix and Curiosity missions coupled with mineralogical and chemical data from a variety of orbital missions, provide important constraints on the geological history of Mars. Professor McLennan is currently funded through the NASA Mars Data Analysis Program to evaluate these results in terms of crustal evolution and the various sedimentary processes that may have operated at the Martian surface during its history.
3. Surficial Processes on Mars: Experimental Approaches
Recent data from the Mars rovers and orbital missions indicate that a variety of unusual evaporite minerals may have been important surface deposits over much of the geological history of Mars. Some of these evaporites may have been influenced by post-depositional (diagenetic) processes, such as oxidation and mineral transformations related to groundwater activity. It is also likely that photochemical processes influenced the chemistry, especially for the halogen elements (e.g., Cl, Br). Evaporative, diagenetic and photochemical processes can be experimentally simulated in the laboratory and such work is ongoing. Another area of interest is to experimentally constrain the nature and stability relationships of the substantial amorphous component in Martian soils and sedimentary rocks observed by the Curiosity rover X-ray diffraction instrument.
4. Geochemical Evolution of Planetary Crusts
Using sedimentary rock major and trace element and radiogenic isotope compositions, Professor McLennan continues to work with long-time collaborator S. Ross Taylor (Australian National University) to evaluate the chemical evolution of Earth's continental crust and the crusts of other planetary bodies. This research resulted in a recently published book (with S. R. Taylor), Planetary Crusts: Their Composition, Origin, and Evolution (Cambridge), which won the Geoscience Information Society's 2010 Award for Best Reference Work.
McLennan, S. M., Anderson, R. B. and 48 others (2014) Elemental geochemistry of sedimentary rocks in Yellowknife Bay, Gale Crater, Mars. Science, 343, doi:10.1126/science.1244734.
Grotzinger, J P., Sumner, D. Y., Kah, L. C., Stack, K., Gupta, S., Edgar, L., Rubin, D., Lewis, K., Schieber, J., Mangold, N., Milliken, R., Conrad, P., DesMarais, D., Farmer, J., Siebach, K.,Calef III, F., Hurowitz, J., McLennan, S. M. and 52 others (2014) A habitable fluvio-lacustrine environment at Yellowknife Bay, Gale Crater, Mars. Science, 343, doi:10.1126/science.1242777.
Dehouck, E., McLennan, S. M., Meslin, P.-Y. and Cousin, A. (2014) Constraints on abundance, composition and nature of X-ray amorphous components of soils and rocks at Gale crater, Mars. J. Geophys. Res. 119, 2640-2657, doi:10.1002/2014JE004716.
Zhao, Y.-Y. S., McLennan, S. M. and Schoonen, M. A. A. (2014) Behavior of bromide, chloride and phosphate during low temperature aqueous Fe(II) oxidation processes on Mars. J. Geophys. Res.-Planets, 119, doi:10.1002/2013JE004417.
McSween Jr., H. Y. and McLennan, S. M. (2014) Mars. In: H. D. Holland and K. Turekian, eds., Treatise on Geochemistry, 2nd Ed.; Vol. 2, A. M. Davis, ed., Planets, Asteroids, Comets and The Solar System (Elsevier, Amsterdam) pp. 251-300.
Karunatillake, S., Zhao, Y.-Y. S., McLennan, S. M., Skok, J. R. and Button, N. E. (2013) Does Martian soil release reactive halogens to the atmosphere? Icarus, 226, 1438-1446.
Grotzinger, J. P., Hayes, A. G., Lamb, M. P. and McLennan, S. M. (2013) Sedimentary processes on Earth, Mars, Titan and Venus. In: S. J. Mackwell et al., eds., Comparative Climatology of Terrestrial Planets, pp. 439-472. Univ. Arizona Press, Tucson.
Johnson, C., McLennan, S. M., McSween, H. Y. and Summons, R. E. (2013) Smaller, better, more: Five decades of advances in geochemistry. In Bickford, M. E., ed. The Web of Geological Sciences: Advances, Impacts, and Interactions, Geol. Soc. Am. Spec Paper 500, 1-44, doi:10.1130/2013.2500(08).
McLennan, S. M. and Taylor, S. R. (2012) Geology, geochemistry and natural abundances of the rare earth elements. In: D. A. Atwood (Ed.) The Rare Earth Elements: Fundamentals and Applications. John Wiley & Sons (Chichester, UK), pp.1-19.
McLennan, S. M. (2012) Geochemistry of sedimentary processes on Mars. In: J. P. Grotzinger and R. E. Milliken (eds.) Mars Sedimentology, SEPM Spec. Publ. 102, 119-138.
McLennan, S. M., Sephton, M. A. and 20 others (2012) Planning for Mars Returned Sample Science: Final report of the MSR End-to-End International Science Analysis Group (E2E-iSAG): A report requested by the Mars Exploration Program Analysis Group (MEPAG). Astrobiology, 12, 175-230.
Hahn, B. C., McLennan, S. M. and Klein, E. C. (2011) Martian surface heat production and crustal heat flow from Mars Odyssey gamma-ray spectrometry. Geophys. Res. Lett. 38, L14203, doi:10.1029/2011GL047345.
Tosca, N. J., McLennan, S. M., Lamb, M. P. and Grotzinger, J. P. (2011) Physicochemical properties of concentrated Martian surface waters. J. Geophys. Res., 116, E05004, doi:10.1029/2010JE003700.
Karunatillake, S., McLennan, S. and Herkenhoff, K. (2010) Regional and grain size influences on the geochemistry of soil at Gusev Crater, Mars. J. Geophys. Res., 115, E00F04, doi:10.1029/2010JE003637.
Taylor, G. J., Boynton, G. J., McLennan, S. M. and Martel, L. M. V. (2010) K and Cl concentrations on the Martain surface determined by the Mars Odyssey gamma ray spectrometer: Implications for bulk halogen abundances in Mars. Geophys. Res. Lett., 37, L12204, doi:10.1029/2010GL043528.
King, P. L. and McLennan, S. M. (2010) Sulfur on Mars. Elements, 6, 107-112.
Taylor, S. R. and McLennan, S. M. (2009) Planetary Crusts: Their Composition, Origin, and Evolution. Cambridge University Press (Cambridge) 378pp.
Karunatillake, S., Wray, J. J., Squyres, S. W., Taylor, G. J., Gasnault, O., McLennan, S. M. and Boynton, W., Maarry, M. R. E. and Dohm, J. M. (2009) Chemically striking regions on Mars and Stealth revisited. J. Geophys. Res. 114, E12001, doi:10.1029/2008JE03303.
Tosca, N. J. and McLennan, S. M. (2009) Experimental constraints on the evaporation of partially oxidized acid-sulfate waters at the martian surface. Geochim. Cosmochim. Acta, 73, 1205-1222.
Tosca, N. J., Knoll, A. H. and McLennan, S. M. (2008) Water activity and the challenge for life on early Mars. Science, 320, 1204-1207.
McLennan, S. M. and Grotzinger, J. P. (2008) The sedimentary rock cycle of Mars. In: J. F. Bell III (ed.) The Martian Surface: Composition, Mineralogy, and Physical Properties. Cambridge Univ. Press (Cambridge), pp. 541-577.
Tosca, N. J., McLennan, S. M., Dyar, M. D., Sklute, E. C. and Michel, F. M. (2008) Fe oxidation processes at Meridiani Planum and implications for secondary Fe mineralogy on Mars. J. Geophys. Res.,113, E05005, doi:10.1029/2007JE003019.
Hahn, B. C., McLennan, S. M., Taylor, G. J., Boynton, W. V. and 9 others (2007) Mars Odyssey gamma-ray spectrometer elemental abundances and apparent relative surface age: Implications for martian crustal evolution. J. Geophys. Res., 112, E03S11, doi:10.1029/2006JE002821.
Hurowitz, J. A. and McLennan, S. M. (2007) A ~3.5 Ga record of water-limited, acidic conditions on Mars. Earth Planet. Sci. Lett., 260, 432-443.
McLennan, S. M., Taylor, S. R. and Hemming, S. R. (2006) Composition, differentiation, and evolution of continental crust: Constraints from sedimentary rocks and heat flow. In: M. Brown and T. Rushmer, eds. Evolution and Differentiation of the Continental Crust. Cambridge Univ. Press, pp. 92-134.
Tosca, N. J. and McLennan, S. M. (2006) Chemical divides and evaporite assemblages on Mars. Earth Planet. Sci. Lett. 241, 21-31.
McLennan, S. M., Bell III, J. F., Calvin, W. and 29 others (2005) Provenance and diagenesis of the evaporite-bearing Burns formation, Meridiani Planum, Mars. Earth Planet. Sci. Lett. 240, 95-121.
Tosca, N. J., McLennan, S. M. et al. (2005) Geochemical modeling of evaporation processes on Mars: Insight from the sedimentary record at Meridiani Planum. Earth Planet. Sci. Lett. 240, 122-148.
Hurowitz, J. A., McLennan, S. M., Tosca, N. J., Arvidson, R. E., Michalski, J. R., Ming, D. W., Schöder, C. and Squyres, S. W. (2005) In-situ and experimental evidence for acidic weathering on Mars. J. Geophys. Res. 111, E02S19, doi:10.1029/2005JE002515.
Tosca, N. J., McLennan, S. M., Lindsley, D. H. and Schoonen, M. A. A. (2004) Acid-sulfate weathering of synthetic Martian basalt: The acid fog model revisited. J. Geophys. Res., 109, E05003, doi:10.1029/2003JE002218.
Squyres, S. W., Grotzinger, J. P., Arvidson, R. E., Bell III, J. F., Christensen, P. R., Clark, B. C., Crisp, J. A., Farrand, W. H., Herkenhoff, K. E., Johnson, J. R., Klingelhöfer, G., Knoll, A. H., McLennan, S. M. and 5 others (2004) In-situ evidence for an ancient aqueous environment on Mars. Science, 306, 1709-1714.
McLennan, S. M. (2003) Sedimentary silica on Mars. Geology, 31, 315-318.
McLennan, S. M. (2001) Relationships between the trace element composition of sedimentary rocks and upper continental crust. Geochem. Geophys. Geosys. 2, 2000GC000109.
McLennan, S. M. (2001) Crustal heat production and the thermal evolution of Mars. Geophys. Res. Lett., 28, 4019-4022.
McLennan, S. M., Bock, B., Compston, W., Hemming, S. R. and McDaniel, D. K. (2001) Detrital zircon geochronology of Taconian and Acadian foreland sedimentary rocks in New England. J. Sed. Res., 71, 305-317.
McLennan, S. M. (2000) Chemical composition of Martian soil and rock: Complex mixing and sedimentary transport. Geophys. Res. Lett., 27, 1335-1338.
Lev, S. M., McLennan, S. M. and Hanson, G. N. (1999) Mineralogic controls on REE mobility during black-shale diagenesis. J. Sed. Res., 69, 1071-1082.
Taylor, S. R. and McLennan, S. M. (1995) The geochemical evolution of the continental crust. Rev. Geophys. , 33, 241-265.
Hemming, S. R., McLennan, S. M. and Hanson, G. N. (1994) Lead isotopes as a provenance tool for quartz: Examples from plutons and quartzite, northeastern Minnesota. Geochim. Cosmochim. Acta, 58,4455-4464.
McLennan, S. M., Hemming, S., McDaniel, D. K. and Hanson, G. N. (1993) Geochemical approaches to sedimentation, provenance and tectonics. In: M. J. Johnsson and A. Basu (Eds.) Processes Controlling the Composition of Clastic Sediments. Geol. Soc. Amer. Spec. Paper 284, 21-40.
McLennan, S. M. (1993) Weathering and global denudation. J. Geol. 101, 295-303.
McLennan, S.M., Taylor, S.R., McCulloch, M.T. and Maynard, J.B. (1990) Geochemical and Nd-Sr isotopic composition of deep sea turbidites: Crustal evolution and plate tectonic associations. Geochim. Cosmochim. Acta 54, 2015-2050.
McLennan, S.M. (1989) Rare earth elements in sedimentary rocks: Influence of provenance and sedimentary processes. Rev. Mineral. 21, 169-200.
Taylor, S. R. and McLennan, S. M. (1985). The Continental Crust: Its Composition and Evolution. Blackwell (Oxford), 312pp.
Externally Funded Research
"Sedimentary Petrology at the MSL Site": NASA/JPL Mars Science Laboratory Participating Scientist Program (2012-2015)
"Sedimentary Petrology at the MER Sites": NASA/JPL Mars Exploration Rover Participating Scientist Program (2002-2015)
"Geochemical Investigations at Meridiani Planum and Gusev Crater": NASA Mars Data Analysis Program (2011-2016)
Recent Graduate Students and Post-Doctoral Fellows
Dr. Erwin Dehouck (Ph.D., Nantes), Post-doctoral Fellow 2013-present.
Yuyan (Sara) Zhao, "Trace Element (Ni, Zn, Cr) and Halogen Geochemistry During Surficial Processes on Mars", Ph.D. (2014).
Dr. Suniti Karunatillake (Ph.D., Cornell), Post-doctoral Fellow 2008-2011 (Assistant Professor, Louisiana State University).
Lauren Beavon, "Trace Element Mobility During Acid Alteration of Martian Basalts", M.S. (2010)
Brian Hahn, "The Chemical Composition and Evolution of the Martian Upper Crust and Near Surface Environment", Ph.D. (2009).
Nicholas J. Tosca, "The Formation and Stability of Saline Minerals at the Martian Surface", Ph.D., 2007 (Lecturer; Oxford University).
News & Announcements
Geosciences Department Newsletter
Melissa Sims chosen to introduce Secretary of Energy at NSLS-II Dedication
Celebrating Robert Cooper Liebermann
Professor Joel Hurowitz named Deputy PI for Mars 2020 Rover Instrument
PhD Student Yuyan (Sara) Zhao selected for Prestigious Dwornik Award
Professor Timothy Glotch to lead NASA funded research team
Professor Martin Schoonen named Chairman of the Environmental Sciences Department at BNL
Professors John Parise and Artem Oganov pursue Materials Genome Initiative
Professor Deanne Rogers finds evidence for past groundwater on Mars
Professor Robert Liebermann accepts Edward A. Flinn Award
Professor Scott McLennan selected for NASA's Mars Science Laboratory Team