Name: Santana Formation
Location:
Brazil
Age:
Lower Cretaceous, 108-92Ma
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Geological Setting and Age


The Santana Formation is one of the series of lithologies making up the complex stratigraphy of the fault-bounded interior 'Araripe Basin'.

The diagram below (after Martill, 1993), illustrates the most widely accepted view of the basin's stratigraphy.

Complex stratigraphy of Araripe Basin (after Martill 1993)

LEGEND

  1. Coarse sands and grits of the Exu Formation.
  2. Laminated silty mudstones of the Simoes Member.
  3. Santana Formation. Mainly mudstones with thin limestones and bands of concretions with fish.
  4. Fine sands, silts and silty mudstones attributable to the Batateiras Formation, and tongues within the Crato, Ipubi and Santana Formations.
  5. Evaporites of the Ipubi Formation.
  6. Organic-rich mudstones and laminated carbonates of the Crato Formation.
  7. Red and green mudstones of the Missao Velha Formation.
  8. Medium to coarse sandstone bodies of fluvial units within the Missao Velha Formation.
  9. Conglomerates, grits and coarse sandstones of the Cariri Formation.
  10. Igneous basement. In places this may be overlain unconformably by the Exu Formation, but there may be some intrusive contacts.
  11. Metamorphic basement. Usually high grade Proterozoic gneisses. Some pelitic rocks in south of basin.

The Santana Formation was deposited during the Early Cretaceous, more specifically during the late Aptian to perhaps Cenomanian (108-92 million years ago; Martill, 1990).

During this time, the supercontinent of Gondwana was breaking up, and South America was rifting from Africa. The palaeoenvironment would therefore have been changeable, as indicated by a highly variable sequence of sediments.

Different interpretations have been proposed in previous years, regarding the stratigraphic sequence of the Araripe Basin; these web-pages incorporate Martill's (1993) nomenclature, but some of the specimens used as illustrations in the Fossil Flora and Fauna pages are from the 'Crato Member'. In Martill's (1993) new nomenclature, this member has been elevated to Formation level ('Crato Formation', and as such should not really be included in this review of 'Santana Formation Fossils'. However it seems a pity to exclude such marvellous images, so they are, in fact included!

Return to Santana Formation Fossils index page


Section author: Sally Haseman
Last updated: 20/11/02