Department of Earth Sciences

Professor of Biogeochemistry

  Ph.D. Geology Geochemistry, Yale University

Research Interests

Sedimentary Geochemistry, Biogeochemical Cycles, Astrobiology

Much of my current work explores the evolving ocean and atmosphere and their cause-and-effect relationships with the origin and evolution of life. Biogeochemical processes that dominate modern and ancient carbonate platforms and oxygen-deficient marine basins are at the heart of this research. Primary methodologies track the signals of microbially mediated cycling of carbon, sulfur, and metals as expressed in their signature isotopic compositions preserved in ancient sedimentary rocks. With my students and colleagues, I am calibrating these proxy methods using modern sediments from the Black Sea, Cariaco Basin in Venezuela, Florida Bay, cold seeps in the Gulf of Mexico, and other settings. We have applied these proxies to deconstruct the paleoenvironmental contexts of Paleozoic black shale deposition and Precambrian biospheric evolution. Particularly exciting are patterns of early atmospheric oxygenation expressed in trace sulfate trapped within carbonate rocks (carbonate-associated sulfate) and in redox-sensitive metals within shales. Related work features marine oxygen isotope records preserved in phosphatic conodonts, iron paleoredox proxies, sulfur geomicrobiology, pathways of metal enrichment, and organic biomarker approaches.

Current Projects and Research Opportunities

Ongoing projects, most with active NSF and NASA funding and student research opportunities, include (1) the molybdenum and iron isotope systematics of modern anoxic marine settings and the associated paleoenvironmental implications; (2) sulfate oxygen and sulfur isotope perspectives on Earth system evolution as refined through experimental microbiology and ground-truthing in the modern ocean; (3) collaborative geochemical exploration of recent drill cores from Western Australia that presage the Great Oxidation Event; (4) high-resolution, parallel carbon and sulfur isotope chemostratigraphy across organic carbon burial events in the Paleozoic; (5) the biogeochemistry of Cretaceous cold seeps in Colorado; (6) geochemical evidence for the causes and consequences of the Permo-Triassic extinction event as recorded globally; and (7) comparisons of Cretaceous oceanic anoxic events as preserved in deep and shallow marine sediments.

Selected publications from last five years

Lyons, T.W., Werne, J.P., Hollander, D.J., and Murray, R.W., 2003, Contrasting sulfur geochemistry and Fe/Al and Mo/Al ratios across the last oxic-to-anoxic transition in the Cariaco Basin, Venezuela: Chemical Geology, v. 195, p. 131-157.

Arnold, G.L., Anbar, A.D., Barling, J., and Lyons, T.W., 2004, Molybdenum isotope evidence for widespread anoxia in mid-Proterozoic oceans: Science, v. 304, p. 87-90.

Kah, L.C., Lyons, T.W., and Frank, T.D., 2004, Evidence for low marine sulphate and protracted oxygenation of the Proterozoic biosphere: Nature, v. 431, p. 834-838.

Lyons, T.W., 2004, Warm debate on early climate: Nature, v. 429, p. 359-360.

Lyons, T.W., Kah, L.C., and Gellatly, A.M., 2004, The Precambrian sulphur isotope record of evolving atmospheric oxygen, in Eriksson, P.G., et al. (eds.), The Precambrian Earth: Tempos and Events: Developments in Precambrian Geology, Elsevier, p. 421-440.

Lyons, T.W., Walter, L.M., Gellatly, A.M., Martini, A.M., and Blake, R.E., 2004, Sites of anomalous organic remineralization in the carbonate sediments of South Florida, U.S.A.: The sulfur cycle and carbonate-associated sulfate: Geological Society of America Special Paper, 379, p. 161-176.

Gellatly, A.M., and Lyons, T.W., 2005, Trace sulfate in Mid-Proterozoic carbonates and the sulfur isotope record of biospheric evolution: Geochimica et Cosmochimica Acta, v. 69, p. 3813-3829.

Johnston, D.T., Wing, B.A., Farquhar, J., Kaufman, A.J., Strauss, H., Lyons, T.W., Kah, L.C., and Canfield, D.E., 2005, Active microbial sulfur disproportionation in the Mesoproterozoic: Science, v, 310, p. 1477-1479.

Lyons, T.W., and Kashgarian, M., 2005, Paradigm lost, paradigm found-The Black Sea-black shale connection as viewed from the anoxic basin margin: Oceanography, v. 18, p. 86-99.

Algeo T.J., and Lyons, T.W., 2006, Mo-TOC covariation in modern anoxic marine environments: Implications for analysis of paleoredox and -hydrographic conditions: Paleoceanography, v. 21.

Lyons, T.W., and Severmann, S., 2006, A critical look at iron paleoredox proxies: New insights from modern euxinic marine basins: Geochimica et Cosmochimica Acta, v. 70, p. 5698-5722.

Lyons, T.W., Gellatly, A.M., and McGoldrick, P.J., 2006, Proterozoic sedimentary exhalative (SEDEX) deposits and their links to evolving global ocean chemistry: Geological Society of America Memoir, 198, p. 169-184.

Anbar, A.D., Duan, Y., Lyons, T.W., Arnold, G.L., Kendall, B., Creaser, R.A., Kaufman, A.J., Gordon, G.W., Garvin, J., and Buick, R., 2007, A whiff of oxygen before the great oxidation event? Science, v. 317, p. 1903-1906.

Kaufman, A.J., Johnston, D.T., Farquhar, J., Masterson, A.L., Lyons, T.W., Bates, S., Anbar, A., Arnold, G.L., Garvin, J., and Buick, R., 2007, Late Archean biospheric oxygenation and atmospheric evolution: Science, v. 317, p. 1900-1903.

Lyons, T.W., 2007, Oxygen's rise reduced: Nature, v. 448, p. 1005-1006.

Lyons, T.W., 2008, Ironing out ocean chemistry at the dawn of animal life. Science, v. 321, p. 923-924.

Scott, C., Lyons, T.W., Bekker, A., Shen, Y., Poulton, S.W., Chu, X., and Anbar, A.D., 2008, Tracing stepwise oxygenation of the Proterozoic ocean: Nature, v. 452, p. 456-459.

Severmann, S., Lyons, T.W., Anbar, A., McManus, J., and Gordon, G., 2008, A modern iron isotope perspective on the benthic iron shuttle and the redox evolution of ancient oceans: Geology, v. 36, p. 487-490.

Werne, J.P., Lyons, T.W., Hollander, D.J., Schouten, S., Hopmans, E.C., and Sinninghe Damsté, J.S., 2008, Investigating pathways of diagenetic organic matter sulfurization using compound-specific sulfur isotope analysis: Geochimica et Cosmochimica Acta, v. 72, p. 3489-3502.

Gill, B.C., Lyons, T.W., and Frank, T.D., 2008, Behavior of carbonate-associated sulfate during meteoric diagenesis and implications for the sulfur isotope paleoproxy: Geochimica et Cosmochimica Acta, v. 72, p. 4699-4711.