NATURAL GAS HYDRATES UP CLOSE: A COMPARISON OF GRAIN CHARACTERISTICS OF SAMPLES FROM MARINE AND PERMAFROST ENVIRONMENTS AS REVEALED BY CRYOGENIC SEM ...

• Main Authors: Stern, Laura A., Kirby, Stephen H.
• Format: Text
• Language: English
• Published: The University of British Columbia 2008
• Subjects: Mackenzie river; permafrost
• Online Access: https://dx.doi.org/10.14288/1.0041020; https://doi.library.ubc.ca/10.14288/1.0041020

Using cryogenic SEM, we investigated the physical states of gas-hydrate-bearing samples recovered by drill core from several localities including the SE India margin (NGHP Expedition 01), Cascadia margin (IODP Leg 311), Gulf of Mexico (RV Marion Dufresne 2002), and Mackenzie River Delta (Mallik site, well 5L-38). Core material with a significant fraction of preserved hydrate has only been obtained for cryogenic SEM investigation from relatively few sites worldwide to date, yet certain consistent textural characteristics, as well as some clear differences between sites have been observed. Gas hydrate in cores recovered from Cascadia, Gulf of Mexico, and Mallik often occurs as a dense substrate with typical grain size of 30 to as large as 200 μm. The hydrate often contains a significant fraction of isolated macropores that are typically 5–100 μm in diameter and occupy 10-30 vol. % of the domain. In fine-grained sediment sections of marine samples, gas hydrate commonly forms small pods or lenses with clay ...