Debz DeFreitas

Debz DeFreitas

Research Associate

Ocean Sciences

  (979) 458-9322

  GERG 117

Selected Publications

  • Wade, T.L., S.T. Sweet, J.L. Sericano, D.A. DeFreitas, and G.G Lauenstein (2014) Polychlorinated dibenzo-p-dioxins and dibenzofurans detected in bivalve samples from the NOAA National Status and Trends Program. Marine Pollution Bulletin 81, 317-324.
  • Sassen, R., H.H. Roberts, W. Jung, C.B. Lutken, D.A. DeFreitas, S.T. Sweet, and N.L. Guinasso, Jr. (2006) The Mississippi Canyon 118 gas hydrate site: A complex natural system. 2006 Offshore Technology Conference, OTC 18132, 10 p.
  • Sassen, R., P. Post, W. Jung, D.A. DeFreitas, and E.C. McDade (2005) Laminated lime mudstone of the Early Oxfordian Smackover Formation of the Northern Gulf Rim: Significance to environments of deposition of carbonate source rocks in rifted basins. 25th Annual Meeting GCSSEPM, p. 1-17.
  • Sassen, R., S.T. Sweet, A.V. Milkov, D.A. DeFreitas, N.L. Eaker, H.H. Roberts and C. Zhang (2004) Brine Vents on the Gulf of Mexico Slope: Hydrocarbons, Carbonate-Barite-Uranium Mineralization, Red Beds, and Life in an Extreme Environment. GCSSEPM 24, 444-463.
  • Sassen, R., H. H., Roberts, R. Carney, A. V. Milkov, D. A. DeFreitas, B. Lanoil and C. Zhang (2004) Free hydrocarbon gas, gas hydrate, and authigenic minerals in chemosynthetic communities of the northern Gulf of Mexico continental slope: relation to microbial processes. Chemical Geology 205, 195-217.
  • Sassen, R., A.V. Milkov, E. Ozgul, H.H. Roberts, J. Hunt, M.A. Beeunas, J. Chanton, D. A. DeFreitas, and S.T. Sweet (2003) Gas venting and subsurface charge in the Green Canyon area, Gulf of Mexico continental slope: evidence of a deep bacterial methane source? Organic Geochemistry 34, 1455-1464.
  • Sassen, R., P.J. Post, D.A. DeFreitas and S.T. Sweet (2003) Geochemistry of an oil seep and gas hydrate on the lower slope, central Gulf of Mexico: significance to paleogeography and possible source rocks. GCAGS / GCSSEPM Transactions 53, 741- 754.
  • Sassen, R., A.V. Milkov, H.H. Roberts, S.T. Sweet and D.A. DeFreitas (2003) Geochemical evidence of rapid hydrocarbon venting from a seafloor-piercing mud diapir, Gulf of Mexico continental shelf. Marine Geology 198, 319-329.
  • Sassen, R., A. V. Milkov, D. A. DeFreitas, S. T. Sweet and H. H. Roberts. (2002) Gas hydrate in the Gulf of Mexico: Significance to sediment deformation. 2002 Offshore Technology Conference. OTC 14034, 7 p.
  • Sassen, R., H.H. Roberts, A.V. Milkov and D.A. DeFreitas (2001) Sea floor vents, seeps, and gas hydrate: relation to flux rate from the deep Gulf of Mexico petroleum system. GCSSEPM 21, 489-505.
  • Sassen, R., S.T. Sweet, A.V. Milkov, D.A. DeFreitas and M.C. Kennicutt II (2001) Stability of thermogenic gas hydrate in the Gulf of Mexico: constraints on models of climate change. In: Natural Gas Hydrates: Occurrence, Distribution, and Detection, Geophysical Monograph 124, 131-143.
  • Sassen, R., S.T. Sweet, D.A. DeFreitas, J.A. Morelos and A.V. Milkov (2001) Gas hydrate and crude oil from the Mississippi Fan Foldbelt, downdip Gulf of Mexico salt basin: significance to petroleum system. Organic Geochemistry 32, 999-1008.
  • Sassen, R., S.L. Losh, L. Cathles III, H.H. Roberts, J.K. Whelan, A.V. Milkov, S.T. Sweet and D.A. DeFreitas (2001) Massive vein-filling gas hydrate: relation to ongoing gas migration from the deep subsurface in the Gulf of Mexico. Marine and Petroleum Geology 18, 551-560.
  • Sassen, R., S.T. Sweet, A.V. Milkov, D.A. DeFreitas and M.C. Kennicutt II (2001) Thermogenic vent gas and gas hydrate in the Gulf of Mexico slope: Is gas hydrate decomposition significant? Geology 29, 107-110.
  • Sassen, R., J.S. Watkins, C. Decker, S.T. Sweet, D.A. DeFreitas and S. Losh (2001) High maturity gas in the Main Pass area: comparison to the central Gulf of Mexico slope. GCAGS Transactions, L1, 285-291.
  • Sassen, R., S.T. Sweet, D.A. DeFreitas and A.V. Milkov (2000) Exclusion of 2-methylbutane (isopentane) during crystallization of structure II gas hydrate in sea-floor sediment, Gulf of Mexico. Organic Geochemistry 31, 1257-1262.
  • Sassen, R., S.T. Sweet, A.V. Milkov and D.A. DeFreitas (2000) Significance of gas hydrates and oils seeps to Mississippi Fan Foldbelt petroleum system: 2000 AAPG Ann. Conv., Prog. and Abs., p. A132.
  • Sassen, R., S.T. Sweet, A.V. Milkov, D.A. DeFreitas, G.G. Salata, E.C. McDade (1999) Geology and geochemistry of gas hydrates, central Gulf of Mexico continental slope. GCAGS Transactions 49, 463-468.
  • Sassen, R., S. Joye, S.T. Sweet, D. A. DeFreitas, A.V. Milkov, and I.R. MacDonald (1999) Thermogenic gas hydrates and hydrocarbon gases in complex chemosynthetic communities, Gulf of Mexico continental slope. Organic Geochemistry 30, 485-497.
  • Sassen, R., J.S. Watkins, C.L. Decker, D.A. DeFreitas, and A. Milkov (1999) Structural setting and geochemistry of gas hydrates, Gulf of Mexico continental slope. Prog. And Abstracts, 1999 AAPG Ann. Mtg., San Antonio, Texas, p. A22.
  • Sassen, R., I.R. MacDonald, N.L. Guinasso, Jr., S. Joye, A.G. Requejo, S.T. Sweet, J. Alcala-Herrera, D.A. DeFreitas, and D.R. Schink (1998) Bacterial methane oxidation in sea-floor gas hydrate: Significance to life in extreme environments. Geology 26, 851-854.
  • Ondrusek, M.E., R.R. Bidigare, S.T. Sweet, D.A. DeFreitas, and J.M. Brooks (1991) Distribution of Phytoplankton Pigments in the North Pacific Ocean in Relation to Physical and Optical Variability. Deep-Sea Research 38: 243-266.
  • Wade, T.L., E.L. Atlas, J.M. Brooks, M.C. Kennicutt II, R.G. Fox, J. Sericano, B. Garcia-Romero, and D. DeFreitas. (1988) NOAA Gulf of Mexico Status and Trends Program: Trace organic contaminant distribution in sediments and oysters. Estuaries 11, 171-179.
  • Kennicutt, M.C. II, C. Barker, J.M. Brooks, D.A. DeFreitas and G.H. Zhu (1987) Selected organic matter source indicators in the Orinoco, Nile and Changjiang deltas. Organic Geochemistry 11, 41-51.
  • Kennicutt, M.C. II, D.A. DeFreitas, J.E. Joyce, and J.M. Brooks (1986) Non-volatile organic matter in sediments from Sites 614 to 623, Deep-Sea Drilling Project Leg 96. In: Initial Reports of the Deep Sea Drilling Project, 96, 747-756.
  • Kennicutt, M.C. II, R.C. Pflaum, D. DeFreitas, J.M. Brooks, and DSDP Leg 96 Shipboard Scientists (1985) Geochemistry of Mississippi Fan sediments. In: Submarine Fans and Related Turbidite Sequences (eds. A. H. Bouma, N. E. Barnes and W. R. Normark), pp. 325-329.

Additional Information


Research Associate, Geochemical and Environmental Research Group, College of Geosciences, Texas A&M University, 1990-.
Research Assistant, Geochemical and Environmental Research Group, Department of Oceanography, Texas A&M University, 1986-1989.
Graduate Assistant Researcher, Department of Oceanography, Texas A&M University, 1980-1986.
Teachers Assistant, Marine Science Department, Stockton State College, 1978.

Professional Service

University Staff Council (USC), 2010 - 2012
USC Executive Officer: Secretary (elected), 2011 - 2012
USC Executive Officer: At-large (elected), 2010 - 2011
Memorial Student Center Opera and Performing Arts Society (MSC OPAS) Board of Directors, 2003-2009


Internal Audits, Management Review, and Corrective Action Training Course, June, 2012
Quality Assurance for Analytical Laboratories, AOAC International Training Course, September, 2008
Assessments for ISO/IEC 17025 and NELAC Basic Assessor Training (ASI Course 300), August, 2007
SCUBA Diving certification (NASDS #EE8911, May 1977)

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