Sequence
Stratigraphy of the Latest Cretaceous and Cenozoic Shelf to Basin Transition NW
Watkinson, Matthew P.1, Mark
A. Enfield2, Edward P. Blunt3 (1) PDF Fellowship,
University of Plymouth, Plymouth, United Kingdom (2) PDF Ltd, Streatley, United
Kingdom (3) Sterling Energy plc, Harpenden, United Kingdom
Significant exploration potential is
recognised in deep water basinal settings offshore NW Madagascar. We present
here the results of detailed structural and seismic sequence stratigraphic
analysis of the shelf to basin transition of the
Sequences of inferred Late Cretaceous age
show evidence of growth across normal fault systems and can be related to
rifting between
Probable Eocene and Oligocene shelf-edge
sedimentation shows dramatic variations along depositional strike caused by
rapid subsidence apparently associated with salt mobilisation. Base-of-slope
mass flow complexes and turbidite systems were ponded and redirected within
small salt withdrawal and structural depocentres.
A series of major regressive events,
thought to be coincident with Oligocene global sea-level falls, led to
by-passing of clastic sediments into basinal areas. Subsequent Neogene
sedimentation was dominated by progradation of deltas to the present day shelf
margin. This regressive phase coincided with uplift of Paleogene sequences and
onshore volcanism. The Neogene inversion of Paleogene depocentres resulted in
alongshore offlap of clastic depositional systems, and to the establishment of
reefal carbonates localised on uplifted highs.
This analysis has improved our
understanding of the distribution, nature and timing of key play elements
(including basin floor reservoirs), and is being applied to help constrain
exploration risk in deep water areas.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California