Seismic and geochemical evidence for shallow gas in sediment on Navarin continental margin, Bering Sea
Marine seismic studies coupled with geochemical investigations demonstrate that hydrocarbon gases are ubiquitous in the near-surface (less than or equal to 250 m or 820 ft depth) sediment of the Navarin continental margin in the northern Bering Sea. Three types of acoustic anomalies appear to be related to the presence of gas in the sediment. These anomalies are most prevalent in the northern half of the Navarin basin. Acoustic anomalies attributed to gas hydrates and to diagenetic boundaries are present on seismic records of the lower slope between Navarinsky and Zhemchug Canyons. Hydrocarbon gases, methane through butanes, are common in the surface sediment of the Navarin continental margin. Methane, the most abundant hydrocarbon gas, is present in amounts ranging from 84,000 to 1 ..mu..L/L of wet sediment. These concentrations are two to three orders of magnitude greater than the other hydrocarbon gases. The highest concentrations of methane (greater than 1,000 ..mu..L/L) were measured in sediment of Navarinsky Canyon and over the central part of the Navarin basin. The source of methane is mainly biogenic, but the hydrocarbon gas compositions in 17 of 141 cores suggest the presence of thermogenic gas. Most of these 17 cores are from the continental slope at water depths greater than 150 m (490 ft). No direct correlation could be found between acoustic anomalies and gas concentrations in the sediment. This lack of correlation is probably due to the limited penetration of the gravity corer and the spotty distribution of hydrocarbon concentrations.
- Research Organization:
- Branch of Pacific Marine Geology, U. S. Geological Survey, Middlefield Road, Menlo Park, California
- OSTI ID:
- 5355657
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 69:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BERING SEA
NATURAL GAS DEPOSITS
GEOCHEMICAL SURVEYS
SEISMIC SURVEYS
SEDIMENTARY ROCKS
GAS SATURATION
CONTINENTAL MARGIN
MARINE SURVEYS
METHANE
NATURAL GAS
ALKANES
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
HYDROCARBONS
MINERAL RESOURCES
ORGANIC COMPOUNDS
PACIFIC OCEAN
RESOURCES
ROCKS
SATURATION
SEAS
SURFACE WATERS
SURVEYS
030200* - Natural Gas- Reserves
Geology
& Exploration