The amounts and compositions of interstitial gases found at the five sites cored on the Demerara Rise during Leg 207 are related to sediment lithology. Concentrations are low in the sedimentary units overlying Cenomanian–Santonian black shales, where they increase to maximum values. A microbial origin for most of the gases is inferred from the low thermal maturity of organic matter and the predominance of methane in their compositions. Active in situ gas generation is postulated to compensate for migration of methane out of the black shale units. Trace amounts of C4–C6 gases found in the black shale units likely migrated from deeper in the section.
1Meyers, P.A., Forster, A., Sturt, H., and the Leg 207 Shipboard Scientific Party, 2004. Microbial gases in black shale sequences on the Demrara Rise. In Erbacher, J., Mosher, D.C., Malone, M.J., et al., Proc. ODP, Init. Repts., 207 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/207_IR/chap_09/chap_09.htm>. [Cited
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2Department of Geological Sciences, University of Michigan, 2534 C.C. Little Building, Ann Arbor MI 48109-1063, USA.
pameyers@umich.edu
3Marine Biogeochemistry and Toxicology (MBT), Nederlands Instituut voor Onderzoek der Zee (NIOZ), PO Box 59, 1790 AB Den Berg, Texel, The Netherlands.
4Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Mail Stop 22, Woods Hole MA 02543, USA.
5Shipboard
Scientific Party addresses can be found under "Shipboard
Scientific Party" in the preliminary pages of the volume.
Ms 207IR-109