Paleogene-Neogene calcareous nannofossil biostratigraphy and paleoecological inferences from northern Campos Basin,Brazil (well Campos-01) |
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| Institution: | 1. Post-Graduate Program in Geology, Unisinos University, São Leopoldo, RS, Brazil;2. Technological Institute of Paleoceanography and Climate Change - Itt Oceaneon, Unisinos University, São Leopoldo, RS, Brazil;3. Laboratory of Plant Paleoecology (LAPAV), National Museum - Federal University of Rio de Janeiro, Brazil;4. Laboratory of Sedimentary Geology (Lagesed), Department of Geology, Institute of Geosciences, UFRJ - Federal University of Rio de Janeiro, Brazil;5. Labmicro, Department of Geology, Institute of Geosciences, UFRJ - Federal University of Rio de Janeiro, Brazil;1. Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, Bari, Italy;2. Instituto Português do Mar e da Atmosfera, Divisão de Geologia e Georecursos Marinhos, Alges, Portugal;3. Centro de Ciências do Mar (CCMAR), Universida de do Algarve, Portugal;4. Universidad de Salamanca, Department of Geology. 37008 Salamanca, Spain;5. American University, Environmental Science Department, Washington, DC, USA;6. National Museum of Natural History, Smithsonian, Paleobiology Department, Washington, DC, USA;7. Institute of Marine Sciences, University of California, Santa Cruz, CA, USA;1. Università degli Studi di Parma, Dipartimento di Scienze Chimiche della Vita e della Sostenibilità ambientale, Parco Area delle Scienze, 157 a, 43124 Parma, Italy;2. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Roma 00143, Italy;3. Instituto Oceanográfico, Universidade de São Paulo, Praça do Oceanográfico, 191, SP 05508-120 São Paulo, Brazil;4. Università degli Studi di Modena e Reggio Emilia, Dipartimento di Scienze Chimiche e Geologiche, Via Campi, 103, 41125 Modena, Italy |
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| Abstract: | Quantitative analyses of calcareous nannofossils were performed on 50 ditch-cuttings samples from a well drilled in the northern Campos Basin, Brazil. Nine zones and two subzones were recognised in the Paleogene-Neogene section. The absence of zones NN9-NN7 (earliest late-latest middle Miocene), NP25-NP21 (Oligocene) and NP18-NP1 (earliest late Eocene-Paleocene) implies the occurrence of three stratigraphic breaks/unconformities within the studied interval. Nannofossil assemblages present suggest an open-ocean depositional environment under oligotrophic-surface water conditions for the Miocene section of the well. Hughesius spp. and Umbilicosphaera spp., here named the “small dark” group, were recognised as an index of high nutrient concentration. We suggest that small coccolith/nannolith size is a better indicator of eutrophic condition than taxonomic affinity. Morphometric analysis of specimens of Sphenolithus belemnos and Sphenolithus disbelemnos showed that size tends to decrease within the highstand system tract. The influx of nutrients associated with the highstand could explain this size reduction and may also support our hypothesis that small specimens are indicative of high nutrient concentrations in the surface water. |
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| Keywords: | Calcareous nannofossils Biostratigraphy Paleoecology Size variation Paleogene-Neogene Campos Basin |
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