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Circulation, Unconformities and Sedimentation |
Ecole Nationale Superieure des Mines, Paris, France
US Geological Survey, Woods Hole, Massachusetts, USA
Institute of Oceanography, University of Southampton
British Geological Survey, Nottingham
Institute of Oceanographic Sciences, Wormley, Godalming, Surrey GUB SUB
Institut Francais du Pétrole, Rueil- Malmaison, France
Geologisch-Paläontologisches Institute, Johann-Wolfgang-Goethe Universität, Frankfurt/Main, Federal Republic of Germany
Centre Océanologique de Bretagne, Brest, France
Vincennes, France
Department of Geology, East Carolina University, Greenville, North Carolina, USA
Resource Reconnaisance Incorporated, Dallas, Texas, USA
Exxon Production Research Company, Houston, Texas, USA
A transect of four coreholes, drilled by the Glomar Challenger across the Irish continental margin at the Goban Spur, evidences a dynamic palaeoceanographic regime during the late Mesozoic and Cenozoic. Shallow marine waters invaded the rift-stage grabens of the Goban Spur in the early Barremian. Thereafter, the margin subsided rapidly, producing a pelagic depositional regime by late Barremian time. Deep marine conditions were maintained as sea-floor spreading began in the early Albian, and chiefly pelagic deposition continued to the present.
Among a series of significant post-rift oceanographic changes, one of the most notable is the familiar fluctuation of oxic and anoxic sea-floor environments during the Cenomanian and Turonian. Another marked change took place during the late Palaeocene, when cooler, oxygen-rich, northern bottom waters reached the Goban Spur as a consequence of rifting and sea-floor spreading between Greenland, Rockall Plateau, and Norway. Later during the Cenozoic, the initial production of Antarctic bottom water, several accelerations of polar icecap growth, and fluctuating eustatic sea-level produced a variety of circulatory shifts on the Goban Spur. A particularly significant sedimentological consequence of these interacting processes was the widespread creation of numerous erosional and non-depositional unconformities.
