Theodore R. Them

Assistant Professor

Address: SSMB 212
Personal Website:


Shippensburg University of Pennsylvania, Shippensburg, PA
B.S., Geoenvironmental Studies, 2008

Texas A&M University, College Station, TX
M.S., Oceanography, 2012

Virginia Tech, Blacksburg, VA
Ph.D., Geosciences, 2016

Florida State University & National High Magnetic Field Laboratory, Tallahassee, FL
Arts and Sciences Postdoctoral Fellow, 2016-2018

Other Appointments

Affiliated Scientist
National High Magnetic Field Laboratory

Graduate Committee Faculty – Department of Oceanography
Texas A&M University

Editorial Board Member
Geology (2022-2024)

Frontiers in Earth Science

Frontiers in Ecology and Evolution

Research Interests

  • Sedimentary Geochemistry, Paleoceanography, Global Environmental Destabilization
  • Mass extinctions and other biological crises
  • Geochemistry of Ancient and Modern Environmental Systems (GAMES) Laboratory
  • Laboratory website

Courses Taught

GEOL 105 Earth History

GEOL 257 Marine Geology

GEOL 288 Global Change: A Geologic Perspective

GEOL 312 Environmental Field Methods

GEOL 495 / EVSS 595 Special Topics: Climate Change: Causes and Consequences

GEOL 495 / EVSS 595 Special Topics: Mass Extinctions and the History of Life

HONS 155L Honors Geology I Lab

HONS 156L Honors Geology II Lab


*Students coauthors


24. Kozik, N.P., Yound, S.A., Newby, S.M., Liu, M., Chen, D., Hammarlund, E.U., Bond, D.P.G., Them II, T.R., Owens, J.D., 2022, Rapid marine oxygen variability: driver of the Late Ordovician mass extinction, Science Advances, 8, eabn8345.

23. Them II, T.R., Owens, J.D., Marroquín, S.M., Caruthers, A.H., Trabucho Alexandre, J.P., Gill, B.C., 2022, Reduced marine molybdenum inventory related to enhanced organic carbon burial and an expansion of reducing environments in the Toarcian (Early Jurassic) oceans, AGU Advances, 3, e2022AV000671.

22. *Veenma, J.P., McCabe, K., Caruthers, A.H., Aberhan, M., Golding, M., Marroquín, S.M., Owens, J.D., Them II, T.R., Gill, B.C., Trabucho Alexandre, J.P., 2022, The Glass Ramp of Wrangellia: Late Triassic to Early Jurassic Outer Ramp Environments of the McCarthy Formation, Alaska, Journal of Sedimentary Research, 92, 896 – 919.

21. Liu, W., Liu, M., Yang, T., Liu, X., Them II, T.R., Wang, K., Bian, C., Meng, Q., Li, Y., Zeng, X., Zhao, W., 2022, Organic matter accumulations in the Santonian-Campanian (Upper Cretaceous) lacustrine Nenjiang shale (K2n) in the Songliao Basin, NE China: terrestrial response to OAE3? International Journal of Coal Geology, 260, 104069.

20. Caruthers, A.H., Marroquín, S.M., Gröcke, D.R., Golding, M., Aberhan, M., Them II, T.R., Veenma, J.P., Owens, J.D., McRoberts, C.A., Friedman, R.M., Trop, J.M. Szúcs, D., Pálfy, J., Rioux, M., Trabucho Alexandre, J.P., Gill, B.C., 2022, New evidence for a long Rhaetian from a Panthalassan section (Wrangell Mountains, Alaska), and regional differences in carbon cycle perturbations at the Triassic-Jurassic transition, Earth and Planetary Science Letters, 577, 117262.


19. Bowman, C.N., Them II, T.R., *Knight, M.D., Kaljo, D., Eriksson, M.E., Hints, O., Martma, T., Owens, J.D., Young, S.A., 2021, A multi-proxy approach to constrain locally reducing conditions in the Baltic Basin during the late Silurian (Ludfordian) Lau carbon isotope excursion, Palaeogeography Palaeoclimatology Palaeoecology, 581, 110624.

18. Liu, M., Ji, C., Hu., H., Xia, G., Yi. H., Them II, T.R., Sun, P., Chen, D., 2021, Variations in microbial ecology during the Toarcian Oceanic Anoxic Event (Early Jurassic) in the Qiangtang Basin, Tibet: evidence from biomarker and carbon isotopes, Palaeogeography Palaeoclimatology Palaeoecology, 580, 110626.


17. Shen, J., Feng, Q., Algeo, T., Liu, J., Zhou, C., Wei, W., Liu, J., Them II, T.R., Gill, B.C., Chen, J., accepted, Sedimentary host phases of mercury (Hg) and implications for use of Hg as a volcanic proxy, Earth and Planetary Science Letters, 543, 116333.

16. Liu, M., Sun, P., Them II, T.R., Li, Y., Sun, S., Gao, X., Huang, X., Tang, Y., 2020, Organic geochemistry of a lacustrine shale across the Toarcian Oceanic Anoxic Event (Early Jurassic) from NE China, Global and Planetary Change, 191, 103214.

15. Sardar Abadi, M., Owens, J.D., Liu, X., Them II, T.R., Cui, X., Heavens, N., Soreghan, G.S., 2020, Atmospheric dust stimulated marine primary productivity during Earth’s penultimate icehouse, Geology, 48 (3), 247 – 251.


14. Moore, C.R., Brooks, M.J., Goodyear, A.C., Ferguson, T.A., Perrotti, A.G., Mitra, S., Listecki, A.M., King, B.C., Mallinson, D.J., Lane, C.S., Knapp, J.D., West, A., Carlson, D.L., Wolbach, W.S., Them II, T.R., Harris, S.M., Pyne-O’Donnell, S., 2019, Sediment cores from White Pond, South Carolina, contain a platinum anomaly, biomass burning peak, and coprophilous spore decline at 12.8 ka, Scientific Reports, 9:15121.

13. Chen, D., Liu, M., Zhou, X., Tang, D., Them II, T.R., Jiang, M., 2019, Upper Ordovician marine red limestones, Tarim basin, NW China: A product of an oxygenated deep ocean and changing climate?, Global and Planetary Change, 183, 103032.

12. *Bowman, C.N., Young, S.A., Kaljo, D., Eriksson, M.E., Them II, T.R., Hints, O., Martma, T., Owens, J.D., 2019, Linking the progressive expansion of reducing conditions to a stepwise mass extinction event in the late Silurian oceans, Geology, 47(10), 968-972.

11. Grasby, S.E., Them, T.R. II, Chen, Z., Yin, R., Ardakani, O.H., 2019, Mercury as a proxy for volcanic emissions in the geologic record, Earth-Science Reviews, 196, 102880.

10. Kozik, N.P., Young, S.A., Bowman, C.N., Saltzman, M.R., Them II, T.R., 2019, Middle-Upper Ordovician (Darriwilian-Sandbian) paired carbon and sulfur isotope stratigraphy from the Appalachian Basin, USA: Implications for dynamic redox conditions spanning the peak of the Great Ordovician Biodiversification Event, Palaeogeography Palaeoclimatology Palaeoecology, 520, 188 – 202.

9. Them, T.R. II, Jagoe, C.H., Caruthers, A.H., Gill, B.C., Grasby, S.E., Gröcke, D.R., Yin, R., Owens, J.D., 2019, Terrestrial sources as the primary delivery mechanism of mercury to the oceans across the Toarcian Oceanic Anoxic Event (Early Jurassic), Earth and Planetary Science Letters, 507, 62 – 72.


8. Owens, J.D. and Them, T.R. II. (2018, November 13). Volcanit eruptions once caused mass extinctions in the oceans - could climate change do the same? The Conversation. Retrieved from

7. Them, T.R. II, Gill, B.C., Caruthers, A.H., Gerhardt, A.M., Gröcke, D.R., Lyons, T.W., *Marroquín, S.M., Nielsen, S.G., Trabucho Alexandre, J.P., Owens, J.D., 2018, Thallium isotopes reveal protracted anoxia during the Toarcian (Early Jurassic) associated with volcanism, carbon burial, and mass extinction, Proceedings of the National Academy of Sciences, 115 (26), 6596 – 6601.

6. Caruthers, A.H., Smith, P.L., Gröcke, D.R., Gill, B.C., Them II, T.R., Trabucho Alexandre, J., 2018, Ammonites of the Pliensbachian-Toarcian (Jurassic) transition, west-central Nevada, USA, Bulletins of American Paleontology, No. 393, 84 pp.


5. Them, T.R. II, Gill, B.C., Selby, D., Gröcke, D.R., Friedman, R.M., Owens, J.D., 2017, Evidence for rapid weathering response to climatic warming during the Toarcian Oceanic Anoxic Event, Scientific Reports, 7:5003.

4. Martindale, R.C., Them, T.R. II, Gill, B.C., *Marroquín, S.M., Knoll, A.H., 2017, A new Early Jurassic fossil Lagerstätte from Ya Ha Tinda, Canada (~183 Ma), Geology, 45, 255 – 258.

3. Them, T.R. II, Gill, B.C., Caruthers, A.H., Gröcke, D.R., *Tulsky, E.T., Martindale, R.C., Poulton, T.P., Smith, P.L., 2017, High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle, Earth and Planetary Science Letters, 459, 118 – 126.


2. Them, T.R. II, Schmidt, M.W., and Lynch-Stieglitz, J., 2015, Millennial-scale tropical atmospheric and Atlantic Ocean circulation change from the Last Glacial Maximum and Marine Isotope Stage 3, Earth and Planetary Science Letters, 427, 47 – 56.


1. Schmidt, M.W., Chang, P., Hertzberg, J.E., Them II, T.R., Ji, L., and Otto-Bliesner, B.L., 2012, Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures, Proceedings of the National Academy of Sciences, 109 (36), 14348 – 14352. 

Peer Reviewer
  • Chemical Geology, Earth and Planetary Science Letters, Geochimica et Cosmochimica Acta, Geology, Global and Planetary Change, Gondwana Research, Nature Communications, Palaeogeography Palaeoclimatology Palaeoecology, Proceedings of the National Academy of Sciences, Science, Science Advances, Scientific Reports, Sedimentology