Geochemistry of gas hydrates of DSDP Hole 84-570 ...

• Main Authors: Kvenvolden, Keith A, Claypool, George E, Threlkeld, Charles N, Sloan, E Dendy
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 1984
• Subjects: Drilling/drill rig; Leg84; Glomar Challenger; Deep Sea Drilling Project DSDP; Methane hydrate
• Online Access: https://dx.doi.org/10.1594/pangaea.763350; https://doi.pangaea.de/10.1594/PANGAEA.763350

During Deep Sea Drilling Project (DSDP) Leg 84 a core 1 m long and 6 cm in diameter of massive gas hydrate was unexpectedly recovered at Site 570 in upper slope sediment of the Middle America Trench offshore of Guatemala. This core contained only 5-7% sediment, the remainder being the solid hydrate composed of gas and water. Samples of the gas hydrate were decomposed under controlled conditions in a closed container maintained at 4°C. Gas pressure increased and asymptotically approached the equilibrium decomposition pressure for an ideal methane hydrate, CH4.5-3/4H2O, of 3930 kPa and approached to this pressure after each time gas was released, until the gas hydrate was completely decomposed. The gas evolved during hydrate decomposition was 99.4% methane, ~0.2% ethane, and ~0.4% CO2. Hydrocarbons from propane to heptane were also present, but in concentrations of less than 100 p.p.m. The carbon-isotopic composition of methane was -41 to -44 per mil, relative to PDB standard. The observed volumetric ... : Supplement to: Kvenvolden, Keith A; Claypool, George E; Threlkeld, Charles N; Sloan, E Dendy (1984): Geochemistry of a naturally occurring massive marine gas hydrate. Organic Geochemistry, 6, 703-713 ...