HR: 1330h
AN: T53A-02 [Abstracts]
TI: A New Starting point for the History of South and Equatorial Atlantic Oceans
AU: * Moulin, M
EM: mmoulin@ifremer.fr
AF: Ifremer, Centre de Brest
DRO/GM
BP. 70, PLOUZANE, 28280 France
AU: Aslanian, D
EM: daslanian@ifremer.fr
AF: Ifremer, Centre de Brest
DRO/GM
BP. 70, PLOUZANE, 28280 France
AU: Olivet, J
EM: jlolivet@ifremer.fr
AF: Ifremer, Centre de Brest
DRO/GM
BP. 70, PLOUZANE, 28280 France
AU: Labails, C
EM: clabails@ifremer.fr
AF: Ifremer, Centre de Brest
DRO/GM
BP. 70, PLOUZANE, 28280 France
AU: Rabineau, M
EM: marina.rabineau@univ-brest.fr
AF: CNRS - UMR 6538, LAB. Domaines Oceaniques
place Nicolas Copernic, PLOUZANE, 29280 France
AB:
The nature and genesis of the large, thinned transitional zone of the continental passive margins is still a matter of
debate. Any further progress in that subject must imply an intregrated structural study of homologous margins, replaced in a
very precise pre-opening kinematic reconstruction to constraint horizontal movements. In South and Equatorial Atlantic
oceans, the pre-opening misfits problem has been already addressed by several authors and requires an assessment of rigidity
of african and/or south american continental plates which border those oceans. Nevertheless the lack of magnetic anomalies,
the pre-opening fit of the Equatorial Atlantic ocean is well constrained due to the presence of well-defined oceanic fracture zones, homologous Demerara and Guinea Plateaus, paralellism of the coasts and Kandi and Sobral continental lineations. This
contraint compels us to resort to intraplate deformation to close the South Atlantic Ocean. Intregrating all continental
deformations of both plates described in the litterature, we propose here the closest pre-opening fit for the Central part of the South Atlantic. This pre-opening fit leaves a large pre-drift thinned basin of several hundred kilometers which cannot
be explained by any process which implies more horizontal movement (stretching, simple shear.). South of the Walvis-Rio
Grande ridges, the pre-opening fit implies intraplate deformation in Paraña, Solado and Colorado basins (South America) as
already suggested by Unternehr et al (1988) and Nrnberg & Mller (1991).
DE: 8105 Continental margins and sedimentary basins
DE: 8109 Continental tectonics--extensional (0905)
DE: 8122 Dynamics, gravity and tectonics
DE: 8130 Heat generation and transport
DE: 8159 Rheology--crust and lithosphere
SC: Tectonophysics [T]
MN: 2005 Joint Assembly