Hydrocarbon gases in ODP Leg 104 samples

Geochemical studies at three ODP Leg 104 sites on the Wring Plateau help define the distribution of hydrocarbon gases in sediment of this prominent feature of the Norwegian continental margin. Low levels of hydrocarbon gas were encountered in sediment of the outer part of the plateau, but sediment o...

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Bibliographic Details
Main Authors: Kvenvolden, Keith A, Golan-Bac, Margaret, McDonald, Thomas J, Pflaum, Ronald C, Brooks, James M
Format: Dataset
Language:English
Published: PANGAEA 1989
Subjects:
104-642
104-643A
104-644
104-644A
COMPCORE
Composite Core
DRILL
Drilling/drill rig
Joides Resolution
Leg104
Norwegian Sea
Ocean Drilling Program
ODP
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.736715
https://doi.org/10.1594/PANGAEA.736715
Description
Summary:Geochemical studies at three ODP Leg 104 sites on the Wring Plateau help define the distribution of hydrocarbon gases in sediment of this prominent feature of the Norwegian continental margin. Low levels of hydrocarbon gas were encountered in sediment of the outer part of the plateau, but sediment of the inner part of the plateau is very gassy. The molecular composition of inner plateau gases (>99.9% methane) and the carbon isotopic composition of the methane (avg. = -76 per mil relative to the PDB standard) clearly show that the gas is biogenic. Heavier hydrocarbon gases accompany this methane, and their presence is probably a result of both chemical and microbial low-temperature diagenesis. Although these heavier hydrocarbons were not detected in sediment of the outer part of the plateau during shipboard analyses, subsequent shore-based analyses showed that these compounds are present at very low concentrations. Methane in the gassy sediment of the inner part of the plateau may be present as gas hydrates, judging from sedimentological and inorganic geochemical considerations, but no discernible gas hydrates were recovered during drilling.

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