Gray Bebout

Department Chair,

Research Interests: 

  • Stable Isotope Geochemistry
  • Petrology
  • Astrobiology
University of California, Los Angeles (Ph.D. in Geological Sciences)
University of Texas, Austin (M.A. in Geology)
University of Texas, Austin (B.S. in Geology)
EES 015, EES 090, EES 131, EES 334, EES 438, EES 471


In his research, Bebout considers the cycling of volatiles among the major Earth reservoirs (atmosphere, hydrosphere, biosphere, and lithosphere), with emphasis on understanding the metamorphic pathways affecting this flux. As another research focus, he explores the intriguing behavior of nitrogen and its utility in tracing modern and ancient biogeochemical cycling on Earth (and beyond). Bebout and his group currently investigate the (slow, non-anthropogenic) cycling of volatiles such as CO2 and N2 at Earth's subduction zones, with related fieldwork onging in the Italian/French Alps and on the North Island of New Zealand (Hikurangi margin). The geochemical analyses on Hikurangi volcanic and cold seep gases are being conducted at the GNS (in Wellington, New Zealand; collaborator Bruce Christenson) and at the University of Tokyo (collaborator Hirochika Sumino) — the analytical work in Bebout's lab is aimed at assessing the subduction C and N inputs (through analyses of seafloor sediments recently recovered by International Ocean Discovery Program Expedition 375) and wall-rock C and N contributions (aerially exposed metasedimentary rocks on the North Island; see the News Feature regarding this project on the Deep Carbon Observatory website HERE).

Bebout teaches in areas of mineralogy, petrology, and (bio)geochemistry, at all levels of the undergraduate program and also at the graduate level. He is particularly committed to instruction and advising of freshman level students, serving as a College of Arts and Sciences Mentor Advisor and thus contributing significantly to the Lehigh/CAS First-Year Experience. He often offers CAS College Seminars, with recent seminar titles/topics including, "Volcanoes and the Ring of Fire" and "Space, The Final Frontier."

Bebout's research laboratory is in the STEPS building, room 261 (across from the elevator in the C-wing), and at the center of this program is a gas-source isotope-ratio mass spectrometer capable of analyzing very small amounts of CO2, N2, and O2.


Bebout's research group working, in the Italian Alps, on records of subduction-zone carbon cycling (left to right: collaborator Samuel Angiboust; Gabe Epstein, EES Ph.D. student; collaborator Thais Hyppolito; Katie Jaeckel, EES M.S. 2017) - our work in this area, on this topic, is at present funded by a large, multi-institution PIRE grant (Partnerships for International Research and Education) from the National Science Foundation (NSF).

EES Ph.D. student Matthew Nikitczuk sampling hyaloclastites in Iceland, as part of a Mars-analog (astrobiology) study of the alteration of volcanic glass (and the search for biosignatures) - this work is collaborative with researchers at the Institute for Planetary Materials, Okayama University, in Misasa, Japan, receiving funding from Okayama Univeristy and MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan).

Helicopter ride to White Island (an active arc volcano), New Zealand, to sample volcanic gases, as a part of an NSF-funded study collaborating with researchers at GNS Science (NZ), University of Tokyo, and University of Minnesota

[see the News Feature regarding this project on the Deep Carbon Observatory website HERE]

Sampling of volcanic gases at Whakaari (White Island), New Zealand, with Bruce Christenson (GNS Science, Wellington, NZ), collaborator in study of Hikurangi volatiles cycling

Selected Publications: