The late Sinemurian carbonate platform and microfossils with Tethyan affinities of the Algarve Basin (South Portugal)

A Lower Jurassic shallow-platform carbonate succession recognized at Alte, in the Algarve Basin (South Portugal), bears a typically Tethyan microfossil assemblage, which had not been documented before in Portugal and allows better dating of the succession. This is mainly composed of intertidal-supra...

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Bibliographic Details
Published in:Facies 2003-01, Vol.48 (1), p.49-60
Main Authors: Azerêdo, Ana C., Manuppella, Giuseppe, Ramalho, Miguel M.
Format: Article
Language:English
Subjects:
Algae
Biogeography
Foraminifera
Fossils
Jurassic
Ostracoda
Paleontology
Sediments
Stratigraphy
Vertical distribution
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Summary:A Lower Jurassic shallow-platform carbonate succession recognized at Alte, in the Algarve Basin (South Portugal), bears a typically Tethyan microfossil assemblage, which had not been documented before in Portugal and allows better dating of the succession. This is mainly composed of intertidal-supratidal sediments, with infrequent subtidal sediments and event deposits, suggesting a marginal-marine, peritidal depositional setting. The microfossil assemblage comprises benthic foraminifera, calcareous algae, porostromates, ostracods andIncertaesedis. As regards to biostratigraphy, the most important are the larger imperforate foraminifera, which includeLituosepta recoarensis, Paleomayncina termieri andPseudopfenderina butterlini?, among other. The vertical distribution of these species indicates that the succession may be confidently dated as Upper Sinemurian, most probably as topmost Sinemurian. The persistence ofL. recoarensis at the top of the sucession indicates that these deposits do not reach the Carixian. The dasyclads are the most important group in the microflora, in particular the typical Liassic speciesPalaeodaysacladus mediterraneus. Also most abundant isThaumatoporella parvovesiculifera. As regards to the Algarve Basin Lower Jurassic shallow-platform formations, it is only in the levels bearing these assemblages that a biostratigraphical constraint is found. The recognition of these Tethyan assemblages also reinforces the knowledge of their palaeogeographical distribution and of the correlative depositional settings in the southern Iberian Peninsula, allowing further comparisons with the North-African region.[PUBLICATION ABSTRACT]
ISSN:0172-9179
1612-4820
DOI:10.1007/BF02667529