Late Ordovician evolution of the intracratonic basins in north-west Gondwana |
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| Authors: | Yngve Grahn Mário V Caputo |
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| Institution: | (1) Institute of Geology and Geochemistry, Stockholm University, S-10691 Stockholm, Sweden;(2) Centro de Geociências, Universidade Federal do Pará, Campus Universitário do Guamá, CEP 66075-970 Belém, Pará, Brazil |
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| Abstract: | The Palaeozoic intracratonic basins in northwest Gondwana, i.e. the Amazonas, Parnaiba and Acera basins, probably opened during late Caradoc and Ashgill times. The fluviatile sedimentation later changed to littoral at the basinal margins. A transgression from the north-west region of Gondwana slowly overlapped the margins of the intracratonic basins. The transgression reached its maximum in the Rawtheyan (late Ashgill), as evidenced by fossiliferous shallow marine sediments in the Amazonas Basin. The Hirnantian glaciation in north Gondwana lowered the sea level, and in the Amazonas Basin a littoral sedimentation followed on shallow marine strata. From the opening of the basins onwards, a shallow sea probably existed close to the epicontinental basins in north-west Gondwana. The basins were connected via a narrow passage between the Guayana and Ivorian cratons. |
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| Keywords: | Ordovician NW Gondwana Intracratonic basins Rheic Ocean Glaciation |
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