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| Format: | Artículo científico |
| Language: | en |
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Academia Brasileira de Ciências
2004
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| Online Access: | https://www.redalyc.org/articulo.oa?id=32776413 |
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Table of Contents:
- Facies analysis of the Codó Formation (Late Aptian) in the Grajaú Area, Southern São Luís-Grajaú Basin Jackson D.S. Paz Dilce F. Rossetti Ana Maria Góes Multidisciplinaria (Ciencias Naturales y Exactas) São Luís evaporite lacustrine Late Aptian Grajaú Basin Facies descriptions of the Codó Formation in the Grajaú area are provided for the first time, and its sedimentarycharacteristics compared to those from the Codó area to allow paleoenvironmental reconstructions. Depositsin the Grajaú area include evaporites, limestones and argillites bearing features indicative of a shallow,low energy, subaqueous, saline environment exposed to meteoric and/or capillary conditions. Floodingevaporativeconcentration-desiccation cycles suggest a saline pan complex surrounded by extensive evaporiticmudflats. The location of the system, whether coastal or inland, is a matter open for debate. However, thelater hypothesis is favored considering: 1. Sr isotopic data, with values higher than those expected forLate Aptian marine waters; 2. calcitic composition of limestones (instead of dolomitic and/or magnesiticas expected in coastal settings); and 3. presence of continental ostracods and lack of marine fauna. Thisinterpretation is consistent with that proposed for UpperAptian deposits of the Codó area, but the depositionalsystem there was one dominated by more stable, well-stratified, anoxic waters and evaporite precipitation incentral lacustrine areas, while in the Grajaú area the salt pan was more oxygenated and ephemeral, with saltprecipitation mainly in marginal areas or along surrounding mudflats. 2004 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32776413 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.76