Deep methane maxima and sup 3 He anomalies across the Pacific entrance to the Celebes Basin

Journal Article · Thu Oct 01 04:00:00 UTC 1987 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(87)90148-7· OSTI ID:7158658

Belviso, S; Jean-Baptiste, P; Nguyen, B C; Merlivat, L; Labeyrie, L ^[1]

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1. Centre des Faibles Radioactivites, Gif-sur-Yvette (France)

Methane and {sup 3}He measurements have been performed in deep waters across the sills between the Pacific Ocean and Celebes Basin. The in situ analyses of dissolved methane have led to the identification of several methane seeps along the flanks of the two South Mindanao submarine ridges. {delta}{sup 3}He excesses in the Celebes Basin and East of Talaud East-Mindanao Ridge at 2000-3000 meter depths are in the range 21-22%, a few percent above the Philippine Sea {sup 3}He background. The isotopic ratio of the added He is 1.8 times the atmospheric ratio, which indicates an input of hydrothermal fluids involving both mantle and crustal/sedimentary components. Methane anomalies are partially associated with these {sup 3}He excesses. The order of magnitude of the CH{sub 4}/{sup 3}He ratios is comparable to those observed in spreading axis hydrothermal fields. At a few tens of kilometers from the top of the Sangihe Ridge, conversely, a major methane anomaly was measured at a depth where the waters show no {sup 3}He enrichment or anomalous water temperature versus the Philippine Sea backgound. This result implies that methane could originate largely from shallow sedimentary layers.

• OSTI ID: 7158658
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 51:10; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150200* -- Geology & Hydrology of Geothermal Systems
58 GEOSCIENCES
580000 -- Geosciences
ALKANES
ASIA
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
DEVELOPING COUNTRIES
ELEMENTS
ENERGY SYSTEMS
FLUIDS
GASES
GEOCHEMISTRY
GEOLOGIC STRUCTURES
GEOTHERMAL FLUIDS
GEOTHERMAL SYSTEMS
HELIUM
HYDROCARBONS
HYDROTHERMAL SYSTEMS
ISLANDS
ISOTOPE RATIO
METHANE
NONMETALS
ORGANIC COMPOUNDS
PACIFIC OCEAN
PHILIPPINES
RARE GASES
SEAS
SEDIMENTARY BASINS
SURFACE WATERS