(Table 1) Crystal sizes of measured samples

• Main Authors: Klapp, Stephan A, Klein, Helmut, Kuhs, Werner F
• Format: Dataset
• Language: English
• Published: PANGAEA 2007
• Subjects: 157-2; 204-1247B; 204-1248C; 204-1249C; 204-1250C; Bush Hill; DEPTH; sediment/rock; Depth comment; DRILL; Drilling/drill rig; Elevation of event; Event label; Grain size; mean; Joides Resolution; Latitude of event; Leg204; Location scan method; Longitude of event; North Pacific Ocean; Ocean Drilling Program; ODP; OTEGA II; Sample code/label; SO174/2; SO174/2_157-2; Sonne; Standard deviation; Television-Grab; TVG; Methane hydrate
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.771920; https://doi.org/10.1594/PANGAEA.771920

Due to experimental difficulties grain size distributions of gas hydrate crystallites are largely unknown in natural samples. For the first time, we were able to determine grain size distributions of six natural gas hydrates for samples retrieved from the Gulf of Mexico and from Hydrate Ridge offshore Oregon from varying depths. High-energy synchrotron radiation provides high photon fluxes as well as high penetration depth and thus allows for investigation of bulk sediment samples. The gas hydrate crystallites appear to be (log-) normally distributed in the natural samples and to be of roughly globular shape. The mean grain sizes are in the range from 300–600 µm with a tendency for bigger grains to occur in greater depth, possibly indicating a difference in the formation age. Laboratory produced methane hydrate, starting from ice and aged for 3 weeks, shows half a log-normal curve with a mean value of ~40 µm. This one order-of-magnitude smaller grain sizes suggests that care must be taken when transposing grain-size sensitive (petro-)physical data from laboratory-made gas hydrates to natural settings.