Controls and
Timing of Structural Inversion in the
Tuitt, Adrian Kern1, John
Underhill2, Derek Ritchie3, Roger Scrutton4,
Howard Johnson3, Ken Hitchen3 (1) University of
Edinburgh, Ediburgh, EH9 3LA, United Kingdom (2) University of Edinburgh,
Edinburgh, United Kingdom (3) British Geological Survey, Edinburgh EH9 3LA, (4)
University of Edinburgh, Edinburgh EH9 3JW,
Continental margins were once thought to
be ‘passive' in nature. However, the interpretation of newly acquired and
existing 2-D seismic data from the Faroe Shelf to the Rockall Plateau has
revealed the presence of prospective anticlinal traps affecting Cenozoic
sediments along the NE Atlantic Margin (eg. Hatton Bank, Ymir
and Wyville Thomson Ridges).
Three unconformities of Late Eocene,
Early-Mid Miocene and Early Pliocene ages have previously been defined and
dated within the South Rockall Trough (Stoker et al., 2001). Whilst these
unconformities were originally attributed to bottom-water current activity at
these times, new evidence available to this study suggests that at least two of
these unconformities were instead formed by previously undocumented
compression. Comparison with other unconformities that have been mapped and
dated elsewhere along the NE Atlantic Margin shows that the growth of the
compressional features primarily occurred during seven main phases - the late
Ypresian, late Lutetian, Late Eocene, Mid Oligocene, Late Oligocene, Miocene
and Early Pliocene.
It remains unclear what the main driver
of the deformation was. However, horizontal compression within the NE Atlantic
Margin resulting from ridge push, Alpine stresses, depth-dependent
stretching and/or plate reorganisation may all have played a role at one time
or another. If they are not dependent upon the disposition of pre-existing
structures, sediment loading or lithospheric structure, the temporal and
spatial variation in the orientation, location, nature and timing of
compressional features may be indicative of the inversion mechanisms involved.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California