Cretaceous Reconstructions of East Antarctica, Africa, and Madagascar

K.M. Marks and A.A. Tikku

Earth and Planetary Science Letters, 186/3-4, 479-495, 2001

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Study Area

Abstract.

Some Cretaceous reconstructions of East Antarctica, Africa, and Madagascar overlap the Mozambique ridge onto the margin of Dronning Maud Land, and others place Madagascar west of the Gunnerus ridge, into the Riiser-Larsen Sea. Our M10Ny (131.9 Ma), M0 (120.4 Ma), 96 Ma, and 34y (83 Ma) marine free-air gravity and topography reconstructions illustrate a solution to the overlap problem and also demonstrate that Madagascar separated from Antarctica east of the Gunnerus ridge. Our reconstructions chronicle the growth of the conjugate Mozambique and Riiser-Larsen Basins created at the Southwest Indian spreading ridge. Well-defined spreading corridors, identified by conjugate fracture zones and Mesozoic magnetic anomaly identifications, extend from one basin into the other. We find that the eastern scarp of the Mozambique ridge aligns with the Astrid ridge, and there is no room for Madagascar west of the Gunnerus ridge. The overlap of the Mozambique Ridge is solved by taking into account the motion of an independent Mozambique ridge microplate that existed from chron M11 to circa M2.

Images and figures follow.

Model B fits best

Alternate Models

Gravity reconstructions confirm Model B

96 Ma reconstruction

Chron 34y, 83 Ma reconstruction

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