Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Collection

toTop

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

home > search >

RAFT TECTONICS IN THE KWANZA BASIN, ANGOLA RID A-3104-2009

Author:
DUVAL, B  CRAMEZ, C  JACKSON, MPA  


Journal:
MARINE AND PETROLEUM GEOLOGY


Issue Date:
1992


Abstract(summary):

Raft tectonics (tectonique en radeaux) allows the extreme thin-skinned extension of overburden over a decollement of thin salt or other evaporites. Rafts are allochthonous fault blocks no longer in mutual contact. In the Kwanza Basin, the type area for raft tectonics, Jurassic-Lower Cretaceous rift fill was succeeded by a cratonic Aptian lowstand progradational wedge. At about 119 Ma, the Massive Salt capped this wedge just before the South Atlantic Ocean began opening. Active spreading caused a eustatic sea level rise and the accumulation of transgressive systems tract carbonates. About 200 km of downdip space for extension on the tilted continental margin was created, mainly by the glide of allochthonous rafts onto fresh oceanic crust. At about 110 Ma, the overburden began to extend when only a few 100 m thick, forming many small, tilted, phase 1 rafts. These older rafts were yoked together by Upper Cretaceous sedimentation before rupturing into huge, non-rotated glide blocks during phase 2 rafting from 55 to 10 Ma. Tertiary sediments accumulated asymmetrically in strike-parallel depocentres created by deep, widening grabens between phase 2 rafts. These sediments rest directly on salt or subsalt strata with a tectonic jump of 60-90 Ma. Strain rates for both phases of rafting varied from 2 x 10(-16) to 3 x 10(-16) s-1.


Page:
389---404


Similar Literature

Submit Feedback

This function is a member function, members do not limit the number of downloads