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| Pessenda,Luiz C.R.; Saia,Soraya E.M.G.; Gouveia,Susy E.M.; Ledru,Marie-Pierre; Sifeddine,Abdelfettah; Amaral,Paula G.C.; Bendassolli,José A.. |
| This study presents paleoenvironmental data based on pollen, elemental and isotopic compositions of organic matter (TOC, N, d13C and d15N) and 14C dating of 170 cm lake sediment record. Samplings have been made in Lagoa Grande at Parque Estadual Turístico do Alto Ribeira - PETAR, Southern São Paulo State, Southeastern Brazil. The variations in relative frequencies (in percentage) of arboreal pollen along the core range between 40 and 80%. The d13C values ranged from -23 to -30 and C/N of ~10 to 15, indicating the contribution of terrestrial C3 plants and algae in the sediment organic matter. The d15N results presented values from 3 to 4.5, also suggesting a mixture of algae and terrestrial C3 plants. The 14C dating indicates modern age for the shallow... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Lacustrine sediment; C and N isotopes; Pollen; Atlantic Forest; Last millennium; Little Ice Age. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000300019 |
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| MENDES,Anderson C.; DANTAS,Ângela B.; RIBEIRO,Anne Caroline S.; SANTOS,Livaldo O.; MENDES,Kamilla C.; MORAES,Dorsan dos Santos; ALMEIDA,Rodolfo M.. |
| ABSTRACT Studies on provenance of minerals in Amazonian rivers focus mostly on suspended sediments, while processes that control bottom-sediment production and distribution are still little known. We determined the provenance of the bottom sediments of Green Lake, a micro-basin draining into the Tapajós River, in the eastern Brazilian Amazon. We used X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and, cathodoluminescence techniques to analyze clay, light and heavy minerals of 22 samples. The lake is L-shaped, with 5.5 m maximum depth, and predominance of mud over sand in the center. Quartz and feldspar were dominant in the light fraction, while zircon, tourmaline, kyanite, rutile, and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Alter do Chão Formation; Lacustrine sediment; Amazon Basin; Santarém; Mineral characterization. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672020000200159 |
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