Rifting, subsidence and continental break-up above a mantle plume in the central South Atlantic
David G. Quirk
Michael Hertle
Jon W. Jeppesen
Madeleine Raven
Webster Ueipass Mohriak
Dorthe J. Kann
Mette Nørgaard
Matthew J. Howe
Dan Hsu
Brian Coffey
Marcos P. Mendes
10.6084/m9.figshare.3453170.v1
https://geolsoc.figshare.com/articles/dataset/Rifting_subsidence_and_continental_break-up_above_a_mantle_plume_in_the_central_South_Atlantic/3453170
<p>New seismic and well data in the deep-water basins of Campos, Santos, South Kwanza and Benguela, supported by plate reconstructions,
help answer fundamental questions on the rifting history of the central South Atlantic, specifically on the amount and effect
of fault-related deformation, and on when and where sea-floor spreading started. The Paraná mantle plume played a fundamental
role – dynamically raising the plate, prolonging continental rifting by heat-softening the crust and, after break-up, delaying
the onset of marine conditions. Previous discrepancies in extension and subsidence have been solved, and the location and
age of the continent–ocean boundary can now be determined. Rifting involved approximately 450 km of homogeneous pure shear,
equivalent to a β factor (lithosphere stretching factor) of 4.5. Break-up occurred at 123 Ma (Barremian–Aptian boundary),
7–8 Ma later than the southern South Atlantic but 6 Ma before widespread salt deposition. The mid-Atlantic ridge was initially
subaerial, marked by a volcanic high. Sea-floor spreading was at a rate of 24 mm year<sup>−1</sup>, similar to syn-rift deformation prior to break-up. Transcontinental strike-slip shear zones are not evident but a major
NW–SE lithospheric lineament associated with a failed triple junction arm had a major influence on the magmatic history, both
prior to and after break-up.
</p>
2016-06-21 11:11:34
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deformation
shear
subsidence
Ma
South Atlantic New
rifting
South Atlantic
Paran á mantle plume
NW
Rifting
Geology