The rare earth element contents of plant specimens of the families Rhamnaceae, Ampelozizyphus amazonicus Ducke (local name: Saracura-Mirá) and of Pteridófitas from genus Gleichenia sp. e Adiantum sp. (ferns)...The rare earth element contents of plant specimens of the families Rhamnaceae, Ampelozizyphus amazonicus Ducke (local name: Saracura-Mirá) and of Pteridófitas from genus Gleichenia sp. e Adiantum sp. (ferns) were determined and compared to those of the soils, in the Pitinga Mine area, Amazon, Brazil. The Pitinga mine district has large tin reserves genetically related to two granite bodies, Agua Boa e Madeira, both intrusive in volcanic rocks included in the Iricoumé Group. This deposit contains, also, bodies of cryolite and rare metals, such as Zr, Nb, Ta, Y and REE. The REE biogeochemical signatures, shown by the collected plants, reflect the patterns of the respective soils. The Eu and Ce anomalies shown by some plant samples are inherited from soils, as well. The higher contents of REE observed in fern samples confirm they are accumulators and reflect the abundance of REE in the soils of Pitinga Mine region. Additionally, that supports their potential use in geochemical exploration and bioremediation. The results of this study stress the importance of biogeochemical research integrated with geochemistry of soils, rocks and minerals.展开更多
The Cemitério Palaeolake deposit in Catalao, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14C yr B.P. ...The Cemitério Palaeolake deposit in Catalao, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14C yr B.P. The unprecedented presence of spongillite and diatomite layers in this deposit was investigated using spicules of continental sponges as proxy data for environmental and climate reconstruction, which was relatively extensive for the ages examined. From the analysis of the sedimentary features and the associations of spicules preserved in the deposit, it was possible to reconstruct the evolution of the limnic system. Five developmental stages were thus identified, corresponding to the installation (lotic and erosion phase), establishment and development of the lake and its colmatation, the latter correlating to the Last Glacial Maximum (LGM). Moreover, based on the ecological requirements of the sponge species identified in the deposit, it was possible to infer the likely weather patterns related to respective phases of the lake. The presence of the sponge species Corvoheteromeyenia australis, presently recorded only from southern South America, indicated that polar incursions originating from the Antarctic were frequent during the last glacial period and might have played a notable role in what is now central Brazil. However, for a short time, drier and hotter weather conditions might have predominated, as suggested by the presence of the species Corvomeyenia thumi.展开更多
文摘The rare earth element contents of plant specimens of the families Rhamnaceae, Ampelozizyphus amazonicus Ducke (local name: Saracura-Mirá) and of Pteridófitas from genus Gleichenia sp. e Adiantum sp. (ferns) were determined and compared to those of the soils, in the Pitinga Mine area, Amazon, Brazil. The Pitinga mine district has large tin reserves genetically related to two granite bodies, Agua Boa e Madeira, both intrusive in volcanic rocks included in the Iricoumé Group. This deposit contains, also, bodies of cryolite and rare metals, such as Zr, Nb, Ta, Y and REE. The REE biogeochemical signatures, shown by the collected plants, reflect the patterns of the respective soils. The Eu and Ce anomalies shown by some plant samples are inherited from soils, as well. The higher contents of REE observed in fern samples confirm they are accumulators and reflect the abundance of REE in the soils of Pitinga Mine region. Additionally, that supports their potential use in geochemical exploration and bioremediation. The results of this study stress the importance of biogeochemical research integrated with geochemistry of soils, rocks and minerals.
基金CNPq for granting of the Universal Project(Process 481555/2009-9)R.Iannuzzi acknowledges CNPq for research fellowship granted(Process PQ305687/2010-7 and PQ309211/2013-1).
文摘The Cemitério Palaeolake deposit in Catalao, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14C yr B.P. The unprecedented presence of spongillite and diatomite layers in this deposit was investigated using spicules of continental sponges as proxy data for environmental and climate reconstruction, which was relatively extensive for the ages examined. From the analysis of the sedimentary features and the associations of spicules preserved in the deposit, it was possible to reconstruct the evolution of the limnic system. Five developmental stages were thus identified, corresponding to the installation (lotic and erosion phase), establishment and development of the lake and its colmatation, the latter correlating to the Last Glacial Maximum (LGM). Moreover, based on the ecological requirements of the sponge species identified in the deposit, it was possible to infer the likely weather patterns related to respective phases of the lake. The presence of the sponge species Corvoheteromeyenia australis, presently recorded only from southern South America, indicated that polar incursions originating from the Antarctic were frequent during the last glacial period and might have played a notable role in what is now central Brazil. However, for a short time, drier and hotter weather conditions might have predominated, as suggested by the presence of the species Corvomeyenia thumi.
