Gas hydrate measurements at Hydrate Ridge using Raman spectroscopy
Hester, K. C.
Dunk, R. M.
White, Sheri N.
Brewer, Peter G.
Peltzer, Edward T.
Sloan, E. D.
MetadataShow full item record
Oceanic gas hydrates have been measured near the seafloor for the first time using a seagoing Raman spectrometer at Hydrate Ridge, Oregon, where extensive layers of hydrates have been found to occur near the seafloor. All of the hydrates analyzed were liberated from the upper meter of the sediment column near active gas venting sites in water depths of 770-780 m. Hydrate properties, such as structure and composition, were measured with significantly less disturbance to the sample than would be realized with core recovery. The natural hydrates measured were sI, with methane as the predominant guest component, and minor/trace amounts of hydrogen sulfide present in three of the twelve samples measured. Methane large-to-small cage occupancy ratios of the hydrates varied from 1.01 to 1.30, in good agreement with measurements of laboratory synthesized and recovered natural hydrates. Although the samples visually appeared to be solid, varying quantities of free methane gas were detected, indicating the presence of occluded gas a hydrate bubble fabric and/or partial hydrate dissociation in the under-saturated seawater.
Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 71: 2947-2959, doi:10.1016/j.gca.2007.03.032.
Showing items related by title, author, creator and subject.
Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate Helgerud, M. B.; Waite, William F.; Kirby, S. H.; Nur, A. (American Geophysical Union, 2009-02-27)We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory-formed polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate. From the wave speed's linear ...
Correction to “Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate” Helgerud, M. B.; Waite, William F.; Kirby, S. H.; Nur, A. (American Geophysical Union, 2009-04-10)
Dai, S.; Santamarina, J. Carlos; Waite, William F.; Kneafsey, Timothy J. (American Geophysical Union, 2012-11-14)The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate ...