Methane anomalies in seawater above the Loihi submarine summit area, Hawaii

Journal Article · Thu Oct 01 00:00:00 EDT 1987 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(87)90163-3· OSTI ID:7259201

Gamo, Toshitaka; Ishibashi, Junichiro; Sakai, Hitoshi ^[1]; Tilbrook, B ^[2]

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1. Univ. of Tokyo (Japan)
2. Univ. of Hawaii, Honolulu (USA)

Hydrothermal activity above Loihi submarine volcano was characterized by water column distributions of methane, pH and helium-3. It was found that the southern Loihi summit is almost covered with hydrothermal plumes, which have anomalously high concentrations of methane (maximum: 569 {times} 10{sup {minus}6} cm{sup 3} kg{sup {minus}}1) accompanied by high concentrations of helium-3 and low pH values (minimum: 7.18). The plumes consist of two layers: a shallow plume (about 200 m above the summit) and a deep plume (about 100 m above the summit), probably derived from different hydrothermal vents. The shallow and deep plumes showed different CH{sub 4}/{sup 3}He and CH{sub 4}/pH ratios with the same {sup 3}He/pH ratio, which implies that methane concentrations differ between the hydrothermal end members for the two plumes. The variation of methane between the end members is suggested to result from inter-vent inhomogeneity of bacterial activities that consume or produce methane within the vents. Comparison of the CH{sub 4}/{sup 3}He ratios of the two plumes with the previous data for Loihi and other submarine hydrothermal areas confirms that the Loihi hotspot has one to two orders of magnitude smaller CH{sub 4}/{sup 3}He value than those of the East Pacific Rise and the Galapagos spreading centers.

• OSTI ID: 7259201
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 51:10; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
HAWAII
HYDROTHERMAL SYSTEMS
THERMAL WATERS
CHEMICAL COMPOSITION
HELIUM COMPOUNDS
METHANE
GEOCHEMISTRY
GEOTHERMAL FLUIDS
PH VALUE
SEAWATER
VOLCANOES
WATER CHEMISTRY
ALKANES
CHEMISTRY
ENERGY SYSTEMS
FEDERAL REGION IX
FLUIDS
GEOTHERMAL SYSTEMS
HYDROCARBONS
HYDROGEN COMPOUNDS
NORTH AMERICA
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
RARE GAS COMPOUNDS
USA
WATER
152001* - Geothermal Data & Theory- Properties of Aqueous Solutions
580000 - Geosciences