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Tectonic Evolution

The Seychelles microcontinent was isolated by a complex tectonic history involving three separate rifting and drifting episodes.

 

The currently accepted tectonic model places Seychelles at the heart of Gondwana, sandwiched between Madagascar and India, during the Permian.  The evolution is illustrated by the next series of snapshots at different geological times.

permian

 

 

 

 

  Initiation of first rifting event

 

At around 225 million years ago the rifting event which eventually split east and west Gondwana was initiated.

255

  

 

Early Cretaceous

 

After east and west Gondwana had separated and Seychelles together with India and Madagascar had moved south along the Davie Fracture zone opening up the Somali Basin.The Amoco wells on the Western Shelf of the Seychelles shows evidence of this rift /drift sequence.

early cretaceous

 

  early Late Cretaceous

Following the second rifting episode that separated Seychelles and India from Madagascar opening up the Mascarene Basin. This second phase of rift tectonism which initiated in the mid Cretaceous (~100 Ma) is believed to have developed quite rapidly with intervening seafloor being created initially at ~85 Ma. The rift sequence, evident along the Seychelles’ Southern and Southeastern Shelves, is represented by a largely undeformed progradational wedge, up to 6000m thick, deposited under what are believed to have been predominantly marine conditions. Such rapid sedimentation during such a short rift cycle suggests the tectonics to have been controlled by strike-slip, or transform movement. Additionally there was counter clockwise rotation associated with this tectonic event which brought the Seychelles to its current orientation.

 

early late cretaceous

 

  Paleocene

 During the Separation of India from the Seychelles opening up the Arabian Basin. India then continued north eventually colliding with Eurasia to form the Himalayas. 

 

paleocene

Exploration provinces

These three phases of rift /drift tectonics have resulted in 3 well defined exploration provinces in the Seychelles. Firstly,the early Mesozoic rotated fault blocks (A) associated with the rifting between Seychelles/Madagascar/India from east Africa, secondly, the late Mesozoic province associated with the break between Madagascar and Seychelles India with the thick prograding wedges (B) being developed along the southern shelf and thirdly, the Tertiary province associated with the final rift phase between India and Seychelles with Tertiary carbonates draping onto older sediments or basement (C). A fourth, gravity defined, exploration province, possibly of Permo-Carboniferous age, is postulated to exist as failed rift grabens (D) within the plateau.

 basins