1887
  1. Home
  2. A-Z Publications
  3. Basin Research
  4. Volume 16, Issue 1
  5. Article
Volume 16 Number 1
  • E-ISSN: 1365-2117

Abstract

Abstract

A new polygonal fault system has been identified in the Lower Congo Basin. This highly faulted interval (HFI), 700±50 m thick, is characterized by small extensional faults displaying a polygonal pattern in plan view. This kind of fracturing is attributed to volumetric contraction of sediments during early stages of compaction at shallow burial depth. 3‐D seismic data permitted the visualization of the progressive deformation of furrows during burial, leading to real fractures, visible on seismic sections at about 78 m below seafloor. We propose a new geometrical model for volumetrical contraction of mud‐dominated sediments. Compaction starts at the water–sediment interface by horizontal contraction, creating furrows perpendicular to the present day slope. During burial, continued shrinkage evolves to radial contraction, generating hexagonal cells of dewatering at 21 m below seafloor. With increasing contraction, several faults generations are progressively initiated from 78 to 700 m burial depth. Numerous faults of the HFI act as highly permeable pathways for deeper fluids. We point out that pockmarks, which represent the imprint of gas, oil or pore water escape on the seafloor, are consistently located at the triple‐junction of three neighbouring hexagonal cells. This is highly relevant for predictive models of the occurrence of seepage structures on the seafloor and for the sealing capacity of sedimentary cover over deeper petroleum reservoirs.

Loading

Article metrics loading...

/content/journals/10.1111/j.1365-2117.2003.00224.x
2004-02-26
2024-04-19

  • From This Site

    /content/journals/10.1111/j.1365-2117.2003.00224.x
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. Brice, S.E., Cochran, M.D., Pardo, G. & Edwards, A.D. (1982) Tectonics and Sedimentation of the South Atlantic Rift Sequence: Cabinda, Angola. In: Studies in Continental Margin Geology (Ed. by W.A.Drake ), AAPG Mem. , 34, 5–18.
    [Google Scholar]
  2. Brown, A.R. (1996) Interpretation of three‐dimensional seismic data. AAPG Mem., 42, 424 p.
  3. Burollet, P.F. (1975) Tectonique en radeaux en Angola. Bull. Soc. Géol. de France, XXII, 503–504.
    [Google Scholar]
  4. Cartwright, J.A. (1994a) Episodic basin‐wide fluid expulsion from geopressured shale sequences in the North Sea basin. Geology, 22, 447–450.
    [Google Scholar]
  5. Cartwright, J.A. (1994b) Episodic basin‐wide hydrofracturing of overpressured Early Cenozoic mudrock sequences in the North Sea Basin. Mar. Petr. Geol., 11 (5), 587–607.
    [Google Scholar]
  6. Cartwright, J.A. & Dewhurst, D.N. (1998) Layer‐bound compaction faults in fine‐grained sediments. Geol. Soc. Am. Bull., 110 (10), 1242–1257.
    [Google Scholar]
  7. Cartwright, J. & Lonergan, L. (1996) Volumetric contraction during the compaction of mudrocks: a mechanism for the development of regional-scale polygonal fault systems. Basin Res., 8, 183–193.
    [Google Scholar]
  8. Cartwright, J.A. & Lonergan, L. (1997) Seismic expression of layer‐bound fault systems of the Eromanga and North Sea Basins. Expl. Geophys., 28, 323–331.
    [Google Scholar]
  9. Clausen, J.A., Gabrielsen, R.H., Reksnes, P.A. & Nysaether, E. (1999) Development of intraformational (Oligocene–Miocene) faults in the northern North Sea: influence of remote stresses and doming of Fennoscandia. J. Struct. Geol., 21 (10), 1457–1475.
    [Google Scholar]
  10. Clausen, O.R. & Korstgard, J.A. (1993) Small scale faulting as an indicator of deformation mechanism in the Tertiary sediments of the northern Danish Central Trough. J. Struct. Geol., 15, 1343–1358.
    [Google Scholar]
  11. Cooper, C.K. (1999) Ocean currents offshore Northern Angola. OTC, paper 10749.
  12. Dewhurst, D.N., Cartwright, J. & Lonergan, L. (1999) The development of polygonal fault systems by syneresis of colloidal sediments. Mar. Petr. Geol., 16, 793–810.
    [Google Scholar]
  13. Droz, L., Rigaut, F., Cochonat, P. & Tofani, R. (1996) Morphology and recent evolution of the Zaire turbidite system (Gulf of Guinea). Geol. Soc. Am. Bull., 108 (3), 253–269.
     [Google Scholar]
  14. Duval, B., Cramez, C. & Jackson, M.P.A. (1992) Raft tectonics in the Kwanza basin, Angola. Mar. Petr. Geol., 9, 389–404.
    [Google Scholar]
  15. Giraudeau, J., Christensen, B.A., Hermelin, O., Lange, C.B., Motoyama, I. & Party, A.S.S. (1998) Biostratigraphic age models and sedimentation rates along the southwest African Margin. In: Proceedings of the ODP, Initial reports, Vol. 175 (Misc: Ed. by G.Wefer , W.H.Berger & C.Richter , pp. 543–546.
    [Google Scholar]
  16. Goulty, N.R. (2001) Mechanics of layer‐bound polygonal faulting in fine‐grained sediments. J. Geol. Soc. London, 159, 239–246.
     [Google Scholar]
  17. Heggland, R. (1998) Gas seepage as an indicator of deeper prospective reservoirs. A study based on exploration 3D seismic data. Mar. Petr. Geol., 15, 1–9.
    [Google Scholar]
  18. Henriet, J.‐P., Batist, M.D. & Verschuren, M. (1991) Early fracturing of Palaeogene clays, southernmost North Sea: Relevance to mechanisms of primary hydrocarbon migration. In: Generation, Accumulation and Production of Europe's Hydrocarbons (Ed. by A.M.Spencer ), Spec. Publ. Eur. Ass. Petr. Geol., 1, 217–227.
    [Google Scholar]
  19. Jansen, J.H., Weering, T.C.E.V., Gieles, R. & Ipresen, J.V. (1984) Middle and Late Quaternary oceanography and climatology of the ZAIRE‐Congo fan and the adjacent eastern Angola Basin. Neth. J. Sea Res., 17, 201–249.
    [Google Scholar]
  20. Kidd, G.D. (1999) Fundamentals of 3D seismic volume visualization. OTC, paper 11054.
  21. Klitgord, K.D. & Grow, J.A. (1980) Jurassic seismic stratigraphy and basement structure of the western Atlantic magnetic quiet zone. AAPG Bulletin, 64, 1658–1680.
    [Google Scholar]
  22. Lachenbruch, A.H. (1962) Mechanics of thermal contraction cracks and ice‐wedge polygons. Geol. Soc. Am., Sp. Paper, 70.
     [Google Scholar]
  23. Lavier, L., Steckler, M. & Brigaud, F. (2000) An improved method for reconstructing the stratigraphy and bathymetry of continental margins: aplication to the Cenozoic tectonic and sedimentary history of the Congo margin. AAPG Bulletin, 84 (7), 923–939.
    [Google Scholar]
  24. Lavier, L. & Steckler, M.S., et al (2001) Climatic and tectonic control on the Cenozoic evolution of the West African margin. Mar. Geol., 178, 63–80.
    [Google Scholar]
  25. Liro, L.M. & Coen, R. (1995) Salt deformation history and postsalt structural trends, offshore southern Gabon, West Africa. In: Salt Tectonics: a Global Perspective (Ed. by M.P.A.Jackson , D.G.Roberts & S.Snelson ), AAPG Mem. , 65, 323–331.
    [Google Scholar]
  26. Lonergan, L., Cartwright, J. & Jolly, R. (1998) The geometry of polygonal fault systems in Tertiary mudrocks of the North Sea. J. Struct. Geol., 20 (5), 529–548.
    [Google Scholar]
  27. Lundin, E.R. (1992) Thin‐skinned extensional tectonics on a salt detachment, northern Kwanza Basin, Angola. Mar. Petr. Geol., 9, 405–411.
    [Google Scholar]
  28. Maltman, A. (1994) The Geological Deformation of Sediments. Chapman & Hall, London.
    [Google Scholar]
  29. Marton, L.G., Tari, G.C. & Lehmann, C.T. (2000) Evolution of the Angola passive margin, West Africa, with emphasis on post‐salt structural styles. In: Atlantic Rifts and Continental Margins (Ed. by W.Moriak & M.Talwani ), Un. Am. Geophys., 129–149.
    [Google Scholar]
  30. Oldham, A.C. & Gibbins, N.M. (1995) Lake Hope 3D: a case study. Expl. Geophys., 26, 383–394.
    [Google Scholar]
  31. Poag, C.W., et al. (1987) Initial Reports of the Deep Sea Drilling Project, 95. U.S. Government Printing Office, Washington D.C.
    [Google Scholar]
  32. Pufahl, P.K., Maslin, M.A., Anderson, L. & Al, E. (1998) Lithostratigraphic summary for LEG 175: Angola–Benguela upwelling system. In: Proc. ODP, Initial reports (Ed. by G.Wefer , W.H.Berger & C.Richter ), 175, 533–542.
    [Google Scholar]
  33. Rouby, D., Raillard, S., Guillocheau, F., Bouroullec, R. & Nalpas, T. (2002) Kinematics of a growth fault/raft system on the West African margin using 3‐D restoration. J. Struct. Geol., 24, 783–796.
    [Google Scholar]
  34. Savoye, B., Cochonat, P.Shipboard Scientific Party (2000) Structure et évolution récente de l'éventail turbiditique du Zaire: premier résultats scientifiques des missions d'exploration Zaiango 1 et 2 (Marge Congo‐Angola). C‐R. Ac. Sci. de la Terre et des Planètes, 331, 211–220
  35. Séranne, M. (1999) Early Oligocene stratigraphic turnover on the West Africa continental margin: a signature of the Tertiary greenhouse-to-icehouse transition? Terra Nova, 11, 135–140.
    [Google Scholar]
  36. Séranne, M., Séguret, M. & Fauchier, M. (1992) Seismic super‐units and post‐rift evolution of the continental passive margin of southern Gabon. Bull. Soc. Géol. de France, 163 (2), 135–146.
    [Google Scholar]
  37. Tuckwell, G.W., Lonergan, L. & Jolly, R. (2003) The control of stress history and flaw distribution on the evolution of polygonal fracture networks. J. Struct. Geol., 25, 1241–1250.
    [Google Scholar]
  38. Uchupi, E. (1992) Angola Basin: geohistory and construction of the continental rise. In: Geologic Evolution of Atlantic Continental Rifts (Ed. by C.W. Poag & P.A. De Graciansky), pp. 77–99. Nostrand Reinhold, New York.
    [Google Scholar]
  39. Uenzelmann‐Neben, G. (1998) Neogene sedimentation history of the Congo Fan. Mar. Petr. Geol., 15, 635–650.
    [Google Scholar]
  40. Vasseur, G., Djeran‐Maigre, I., Grunberger, D., Rousset, G., Tessier, D. & Velde, B. (1995) Evolution of structural and physical parameters of clays during experimental compaction. Mar. Petr. Geol., 12 (8), 941–954.
    [Google Scholar]
  41. Watterson, J., Walsh, J., Nicol, A., Nell, P.A.R. & Bretan, P.G. (2000) Geometry and origin of a polygonal fault system. J. Geol. Soc., 157, 151–162.
    [Google Scholar]
  42. Wefer, G., Berger, W.H. & Richter, C. (1998a) Proc. ODP, Initial Reports, 175.
  43. Wefer, G., Berger, W.H., Richter, C. & Party, A.S.S. (1998b) Facies patterns and authigenic minerals of upwelling deposits off Southwest Africa. In: Procceedings of the ODP, Initial reports, Vol. 175 (Misc: Ed. by G.Wefer , W.H.Berger & C.Richter , pp. 487–504.
    [Google Scholar]
  44. Weinberger, R. (1999) Initiation and growth of cracks during desiccation of stratified muddy sediments. J. Struct. Geol., 21, 379–386.
    [Google Scholar]
  45. Yu, Z. & Lerche, I. (1996) Modelling abnormal pressure development in sandstone/shale basins. Mar. Petr. Geol., 13 (2), 179–193.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/j.1365-2117.2003.00224.x
Loading
Polygonal faults‐furrows system related to early stages of compaction – upper Miocene to recent sediments of the Lower Congo Basin
Basin Research 16, 101 (2004); https://doi.org/10.1111/j.1365-2117.2003.00224.x
/content/journals/10.1111/j.1365-2117.2003.00224.x
/content/journals/10.1111/j.1365-2117.2003.00224.x
Loading

Data & Media loading...

  • Article Type: Research Article

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error