Seismic
Geomorphology and Evolution of a Submarine Channel System:
Catterall, Vicky1, Jonathan
Redfern1, Dorthe Moeller Hansen1, Rob Gawthorpe1
(1)
High-resolution 3D-seismic data (acquired
by BG-Group) from the western Nile Delta slope provides excellent coverage of a
Plio-Pleistocene submarine channel system. The basal erosion surface of the
channel system has been mapped and the internal architecture of its fill imaged
using seismic attributes. The channel system has a straight-line valley length
of >50 km, and can be subdivided into proximal, middle, and distal zones
based on its morphological evolution downslope.
In the proximal zone, the basal erosion
surface is strongly incisional, with an asymmetric form, steeper to the west. A
high-amplitude facies is located above the basal erosion surface. Within this
facies, vertically stacked channel bodies are imaged and channel stacking is
located toward the west of the basal erosion surface. 80% of the high-amplitude
facies is confined by incision of the basal erosion surface and 20% by overbank
aggradation
In the middle zone, incision of the basal
erosion surface increases, its width decreases and very high-amplitude facies
is located above the basal erosion surface. The ratio of fill
confined by incision, to that confined by overbank aggradation changes
downslope from 60:40 to 30:70. Geomorphological change is clearly
influenced by the Nile Delta Offshore Anticline (NDOA) and Rosetta Fault
system.
In the distal zone, two channel-levee
complexes (CLC's) can be distinguished. The older eastern CLC is smaller and
shows lateral migration contemporaneous with vertical stacking.
The quantitative assessment and
observations of downslope changes of architectural style documents a link
between development of local structure (faulting and folding) and channel
evolution.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California