Chemical and isotopic evidence for the nature of the fluid in CH4-containing sediments of the Håkon Mosby Mud Volcano

Abstract The pore waters of CH4-containing sediments of the Håkon Mosby Mud Volcano were rich in NH+4, Br-, and I-; exhibited a high total alkalinity; but were poor in Cl-and SO2-4. The geological evidence and our data suggest that organic matter decomposition in preglacial or early interglacial sediments took place during early diagenesis (bacterial processes) and during metamorphism (thermogenic processes under the 3100-m-thick layer of glacial sediments), accompanied by mud volcano fluid generation. It is argued that the CH4of the mud volcano sediments has a mixed, biogenic and thermogenic, origin.

[1]  Pierre Henry,et al.  Chemical and isotopic evidence for sources of fluids in a mud volcano field seaward of the Barbados accretionary wedge , 1996 .

[2]  T. Collett.  Permafrost‐Associated Gas Hydrate Accumulations a , 1994 .

[3]  W. Reeburgh,et al.  METHANE CONSUMPTION IN CARIACO TRENCH WATERS AND SEDIMENTS , 1976 .

[4]  E. Seke,et al.  Fluid expulsion sites on the Cascadia accretionary prism: mapping diagenetic deposits with processed GLORIA imagery , 1994 .

[5]  Martin Schoell,et al.  Multiple origins of methane in the Earth , 1988 .

[6]  H. Schwarcz,et al.  Radiometric dating of submarine hydrocarbon seeps in the Gulf of Mexico , 1997 .

[7]  W. Borowski,et al.  Carbon cycling within the upper methanogenic zone of continental rise sediments; An example from the methane-rich sediments overlying the Blake Ridge gas hydrate deposits , 1997 .

[8]  Y. Tatsumi.  Fluids in Subduction Zones: J. Tarney, K.T. Pickering, R.I. Knipe and J.E. Dewey (Editors), Cambridge University Press, 1991, 192 pp., hardback, £37.50 ($69.95), ISBN 0 521 413133 , 1992 .

[9]  X. Pichon,et al.  Mud volcano field seaward of the Barbados Accretionary Complex: A submersible survey , 1990 .

[10]  B. Simoneit,et al.  Origin of gases and condensates in the Guaymas Basin hydrothermal system (Gulf of California) , 1988 .

[11]  W. Borowski,et al.  Sources of Biogenic Methane to Form Marine Gas Hydrates In Situ Production or Upward Migration? a , 1993 .

[12]  L. M. Walter,et al.  Microbial generation of economic accumulations of methane within a shallow organic-rich shale , 1996, Nature.

[13]  Alexei V. Milkov,et al.  Haakon Mosby Mud Volcano provides unusual example of venting , 1997 .

[14]  W. Borowski,et al.  Marine pore-water sulfate profiles indicate in situ methane flux from underlying gas hydrate , 1996 .