Restoration Across the Kwanza, Basin, Angola
Exposure of the nappe
toe removed the buttress provided by abyssal-plain cover, which rejuvenated
seaward translation. Third, Miocene basement uplift below the shelf steepened
the bathymetric slope and greatly accelerated downslope translation. This
deformation is now slowing because thickening sediments on the abyssal
plain have reduced the relief of the system and blocked salt-napped advance.
of a 375-km-long section across the Kwanza Basin, Angola, shows
three stages of deformation detached on Aptian salt, each caused
by basement activity. First, tilting related to postrift thermal
subsidence initiated early Albian deformation, shortly after salt
deposition ended. Deformation waned in the late Albian, probably
owing to thinning of salt lubricant beneath the extensional province.
The second phase of deformation was triggered by hitherto unrecognized
crustal uplift beneath the continental rise around 75 Ma (Campanian).
Uplift of the thick salt plateau led to salt extrusion and seaward
advance of the Angola Salt Nappe over the abyssal plain.
changes in basin configuration led to profound changes in detached deformation.
Miocene uplift was only a few hundred meters on the shelf, but this was
sufficient to destabilize the system and cause the translation rate to increase
from 300 to 3200 m/m.y. Deposition of 600 m of sediment on the abyssal plain
in the upper Miocene shifted contractional deformation 150 km landward.
We conclude that driving and resisting forces have been precariously balanced
for much of the Kwanza Basin's history.
information, please contact Michael Hudec. Telephone 512-471-1428. E-mail