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Pacific Coastal & Marine Science Center

A Global Inventory of Natural Gas Hydrate Occurrence

by Keith A. Kvenvolden and Thomas D. Lorenson

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Gas Hydrate Samples - P2b

Map Code: P2b (PDF version)
Reference: Shipboard Scientific Party, 1997, Site 1041: Proceedings, Ocean Drilling Program, Initial Reports, v. 170, p. 153-188.
Geographic/
Geologic Location:
Pacific Ocean
Middle America Trench, an active convergent margin
Offshore from Costa Rica, continental slope
ODP Leg 170, Site 1041
Core/Sample Count: 9 samples
Latitude/
Longitude:
09°44.0’N/86°06.9’W
Water Depth: 3306 m
Sediment Depth: 199-259 meters below sea floor (mbsf)
Description
of Gas Hydrate:
"At this site, gas hydrate is mostly concentrated between about 120 and 280 mbsf, the zone of highest TOC content of 1-2.5 wt%. Its primary mode of occurrence is disseminated, with very thin sheets of gas hydrate filling micro-fractures, as indicated by the almost constant salinity and chlorinity in this depth interval."
Analytical Results: The gas-hydrate sample analyzed within this interval (120-280 mbsf) is composed mainly of methane accompanied by amounts of the higher molecular weight hydrocarbons ethane and propane. The volumentric ratio of gas to water ranged from 120 to 140."
Inferred Evidence
for Gas Hydrate:
See Map Code P2a.
 
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Content Last Modified: 2001 [poster update 17Nov10 (lzt)]

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