University of California, Riverside

Department of Earth Sciences



Timothy Lyons


LyonsProfessor of Biogeochemistry

Ph.D. Geology Geochemistry, Yale University
M.Phil. Geology, Yale University
M.S. Geology, University of Arizona
B.S. Geological Engineering, Colorado School of Mines

Email: timothy.lyons@ucr.edu
Phone: (951)827-3106
Fax (951)827-4324
Office: Pierce Hall 2360



 


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.

Representative Publications Over Last Five Years

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, p. 1016.

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.

Tribovillard, N., Algeo, T., Lyons, T., and Riboulleau, A., 2006, Trace metal proxies for paleoredox and paleoproductivity: Chemical Geology, v. 232, p. 12-32.

Anbar, A.D., Duan, Y., Lyons, T.W., Arnold, G.L., Kendall, B., Creaser, R.A., Kaufman, A.J., Gordon, Scott, C., 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.

Donahue, M.A., Werne, J.P., Meile, C., and Lyons, T.W., 2008, Modeling sulfur isotope fractionation and differential diffusion during sulfate reduction in sediments of the Cariaco Basin: Geochimica et Cosmochimica Acta, v. 72, p. 2287-2297.

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.

Bright, C.A., Cruse, A.M., Lyons, A.M., MacLeod, K.G., Glascock, M.D., and Ethington, R.L., 2009, Seawater rare-earth patterns preserved in apatite of Pennsylvanian conodonts? Geochimica et Cosmochimica Acta, v. 73, p. 1609-1624. 

Gordon, G.W., Lyons, T.W., Arnold, G.L., Roe, J., Sageman, B.B., and Anbar, A.D., 2009, When do black shales shales tell molybdenum tales? Geology, v. 37, p. 535-538.

Lyons, T.W., and Reinhard, C.T., 2009, Oxygen for heavy-metal fans: Nature, v. 461, p. 179-181.

Lyons, T.W., Anbar, A.D., Severmann, S., Scott, C., and Gill B.C., 2009, Tracking euxinia in the ancient ocean: A multiproxy perspective and Proterozoic case study: Annual Reviews of Earth and Planetary Sciences, v. 37, p. 507-534.

Lyons, T.W., Reinhard, C.T., and Scott, C., 2009, Redox redux: Geobiology, v. 7, p. 489-494.

Planavsky, N., Reid, R.P., Lyons, T.W., Myshrall, K.L., and Visscher, P.T., 2009, Formation and diagenesis of modern calcified cyanobacteria: Geobiolgy, v. 7, p. 1-11.

Reinhard, C., Raiswell, R., Scott, C., Anbar, A.D., and Lyons, T.W., 2009, A late Archean sulfidic sea stimulated by early oxidative weathering of the continents: Science, v. 326, p. 713-716.

Ries, J.B., Fike, D.A., Pratt, L.M., Lyons, T.W., and Grotzinger, J.P., 2009, Superheavy pyrite (d34Spyr > d34SCAS) in the terminal Proterozoic Nama Group, southern Namibia: A consequence of low seawater sulfate at the dawn of animal life: Geology, v. 37, p. 743-746.

Duan, Y., Anbar, A.D., Arnold, G.L., Lyons, T.W., Gordon, G.W., and Kendall, B., 2010, Molybdenum isotope evidence for mild environmental oxygenation before the Great Oxidation Event: Geochimica et Cosmochimica Acta, v. 74, p. 6655-6668.

Duan, Y., Severmann, S., Anbar, A.D., Lyons, T.W., Gordon, G.W., and Sageman, B.B., 2010, Isotopic evidence for Fe cycling and repartitioning in ancient oxygen-deficient settings: Examples from black shales of the mid-to-late Devonian Appalachian basin: Earth and Planetary Science Letters: v. 290, p. 244-253.

Kendall, B., Reinhard, C.T., Lyons, T.W., Kaufman, A.J., Poulton, S.W., and Anbar, A.D., 2010, Pervasive oxygenation along the late Archaean ocean margins: Nature Geoscience, v. 3, p. 647-652.

Li, C., Love, G.D., Lyons, T.W., Fike, D.A., Sessions, A.L., and Chu, X., 2010, A stratified redox model for the Ediacaran ocean: Science, v. 328, p. 80-83.

Li, X., Gilhooly, W.P., Zerkle, A.L., Lyons, T.W., Farquhar, J., Werne, J.P., Varela, R., and Scranton, M.I., 2010, Stable sulfur isotopes in the water column of the Cariaco Basin: Geochimica et Cosmochimica Acta, v. 74, p. 6764-6778.

Lyons, T.W., and Gill, B.C., 2010, Ancient sulfur cycling and oxygenation of the early biosphere: Elements, v. 6, p. 93-99.

Planavsky, N., Bekker, A., Rouxel, O.J., Kamber, B., Hofmann, A., Knudsen, A., and Lyons, T.W., 2010, Rare earth element and yttrium compositions of Archean and Paleoproterozoic Fe formations revisited: New perspectives on the significance and mechanisms of deposition: Geochimica et Cosmochimica Acta, v. 74, p. 6378-6405.

Planavsky, N.J., Rouxel, O.J., Bekker, A., Lalonde, S.V., Konhauser, K.O., Reinhard, C.T., and Lyons, T.W., 2010, The evolution of the marine phosphate reservoir: Nature, v. 467, p. 1088-1090.

Turchyn, A.V., Brüchert, V., Lyons, T.W., Engel, G.S., Balci, N., Schrag, D.P., and Brunner, B., 2010, Kinetic oxygen isotope effects during dissimilatory sulfate reduction: A combined theoretical and experimental approach: Geochimica et Cosmochimica Acta, v. 74, p. 2011-2024.

Gill, B.C., Lyons, T.W., Young, S.A., Kump, L.R., Knoll, A.H., and Saltzman, M.R., 2011, Geochemical evidence for widespread euxinia in the later Cambrian ocean: Nature (in press, 1/6/11 publication date).

Li, X., Cutter, G.A., Thunell, R.C., Tappa, E., Gilhooly, W.P., Lyons, T.W., Astor, Y., and Scranton, M.I., 2011, Particulate sulfur species in the water column of the Cariaco Basin: Geochimica et Cosmochimica Act, v. 75, p. 148-163.

Raiswell, R., Reinhard, C.T., Derkowski, A., Owens, J., Bottrell, S.H., Anbar, A.D., and Lyons, T.W., 2011, Formation of syngenetic and early diagenetic iron minerals in the late Archean Mt. McRae Shale, Hamersley Basin, Australia: New insights on the patterns, controls and paleoenvironmental implications of authigenic mineral formation: Geochimica et Cosmochimica Acta (in press).

Scott, C., Bekker, A., Reinhard, C.T., Schnetger, B., Krapež, Rumble, D., and Lyons, T.W., 2011, Late Archean euxinic conditions before the rise of atmospheric oxygen: Geology (in press, 2/11 publication date).

 

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