Gulf of Mexico Sediment Evaluations for Microbial-Mineral-Hydrate Associations

Rudy E. Rogers¹, Jennifer L. Dearman¹, Guochang Zhang¹, Wilbur W. Wilson², and Carol B. Lutken^3
1Chemical Engineering, Mississippi State University, Mississippi State, MS
²Chemistry, Mississippi State University, Mississippi State, MS
³Center for Marine Resources and Environmental Technology, University of Mississippi, University, MS

It is known that microbial activities around seafloor gas hydrate accumulations and gas vents far surpass activities remote from hydrates, and the formed hydrates establish a large carbon sink for microbes. This paper reports on investigations into possible roles minerals and microbes, individually and in association, may play in hydrate nucleation, formation rate, induction time and placement. To do this, we have analyzed in the laboratory numerous hydrate-related sediments from Gulf of Mexico cores. Near-surface sediments and sediments down to 30 m below-surface show interesting trends of hydrate formation propensity. For example, differences in bio-products above and below the sulfate reduction zone may account for the trends. Other sediments were injected with a known biopolymer in the laboratory, the hydrate collected, and the melt analyzed; particles in the melt that had been extracted from the sediments by hydrate crystallization were found to be predominantly about 138 nm diameter and may have acted as hydrate nuclei. The melt from a sample of gas hydrate recovered from an outcrop at MC-118 site from 3000 ft water depth in the Gulf of Mexico was analyzed for particle size by Dynamic Light Scattering and viewed with Scanning Electron Microscope. The melt from this seafloor hydrate showed prolific microbial action that had developed within the interstitial spaces of the hydrate matrix.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas