Douglas Gordon Evans1
(1) Western Geophysical, London, United Kingdom
ABSTRACT: A Depositional Analogue for the Miocene Channel Play of Angola:The Kwanza Canyon
The Miocene channel play of offshore Angola contains the recent giant discoveries of Girassol, Dahlia etc. A newly identified seabed canyon, named the 'Kwanza Canyon', is considered a modern day depositional analogue for these channel systems.
The Kwanza Canyon lies offshore of Luanda in the Kwanza Basin. The canyon was first recognised on bathymetric data recorded with 3D seismic data, and once identified was traced across older 2D seismic data sets. It can be followed for over 300 km from near the coast to the abyssal plain, in water depths that vary from 100m to greater than 3km.
On its course through the 3D data set the canyon can be examined in detail, it exhibits a high degree of sinuosity, is deeply incised, possesses abandoned meanders/channels and feeder canyons.
The Kwanza Canyon is thought to be a long-lived featured that is underlain by preserved earlier canyon cuts. These contain high amplitude events, which are sinuous and are interpreted to be channel sands.
Comparisons between the Kwanza Canyon and 'paleo' channel/canyon systems are made using seismic data
The Kwanza Canyon eventually reaches the abyssal plain. A recent 3D covering part of the abyssal plain is used to provide examples of the resultant types of deposition that are found. These include fans and meandering channels seen in timeslice & profile in this new frontier area.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado