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The great West African Tertiary coastal uplift: Fact or fiction? A perspective from the Angolan divergent margin
Author(s) -
Jackson M. P. A.,
Hudec M. R.,
Hegarty K. A.
Publication year - 2005
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2005tc001836
Subject(s) - geology , paleontology , fission track dating , precambrian , plateau (mathematics) , rift , structural basin , biozone , tectonic uplift , tectonics , mathematics , mathematical analysis
We explore exhumation in the coastal Kwanza Basin by combining analyses of Tertiary hiatuses and apatite fission tracks. Planktonic biozones show five major hiatuses in the Oligo‐Miocene and Plio‐Pleistocene. Between gaps, Oligo‐Miocene strata accumulated under marine conditions. A marine setting refutes the idea of a massively raised coastal plateau in the mid‐Tertiary. Marine conditions continued until ∼5 Ma. Fission track data suggest three thermal events: ∼150 Ma, during rifting and volcanism; ∼100–70 Ma, during shortening and volcanism; and ∼20–10 Ma, during exhumation. Tertiary uplift was spatially highly variable. For the Kwanza Basin, we infer that Tertiary uplift on the West African margin is indeed a fact but that estimates of uplift timing and size are unreliable when extrapolated to adjoining areas. Massive uplift (2000–4000 m) of the Precambrian craton had little structural effect in the outer basin. Instead, minor uplifts on the shelf drove late Tertiary deformation on the slope.