IADO   05364
INSTITUTO ARGENTINO DE OCEANOGRAFIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Tallo concreciones fósiles en las barrancas del Río Quequén Salado, Buenos Aires, Argentina
Autor/es:
LUNA, L., .; SCHILLIZZI, R. A; GUTIERREZ TELLEZ, B.
Lugar:
Cordoba
Reunión:
Congreso; III Congreso Argentino de Cuaternario y Geomorfología; 2006
Institución organizadora:
Universidad Nacional de Cordoba
Resumen:
Abstract Phytoconcretions are related with the pedological features of a sedimentary unit. In Buenos Aires province vegetal concretions are very common while bibliography related to shootconcretions is scarce. The aim of this study is to determine origin, genesis, depositional substrate and cronostratigraphical position of the shootconcretions at a profile (Usina 2) of the Quequén Salado river. The sedimentary column is composed by silty sand and silty clayed sand towards the top of the profile. The ferruginous shootconcretions vary from 1 to 5 cm in diameter and 25 cm long. They are composed of redish sandy layers related to plants and very fine yellowish sandy layers, with a central hollow axe invaded by actual roots. Optical microscopic observations show tissues cells which relate ancient shootconcretions with recent angiospermae dicotyledon shoots. Evidence of ants activity were seen in the ancient shootconcretions. Plants and ants would colonized an inactive river bed which would be quickly buried turning to an immature soil; the latter is correlated with Puesto Callejón Viejo soil. Iron oxide precipitation would be related with sedimentary bacterium present at the sourrounding sediment. This process would take place during Pleistocene-Holocene epochs.Phytoconcretions are related with the pedological features of a sedimentary unit. In Buenos Aires province vegetal concretions are very common while bibliography related to shootconcretions is scarce. The aim of this study is to determine origin, genesis, depositional substrate and cronostratigraphical position of the shootconcretions at a profile (Usina 2) of the Quequén Salado river. The sedimentary column is composed by silty sand and silty clayed sand towards the top of the profile. The ferruginous shootconcretions vary from 1 to 5 cm in diameter and 25 cm long. They are composed of redish sandy layers related to plants and very fine yellowish sandy layers, with a central hollow axe invaded by actual roots. Optical microscopic observations show tissues cells which relate ancient shootconcretions with recent angiospermae dicotyledon shoots. Evidence of ants activity were seen in the ancient shootconcretions. Plants and ants would colonized an inactive river bed which would be quickly buried turning to an immature soil; the latter is correlated with Puesto Callejón Viejo soil. Iron oxide precipitation would be related with sedimentary bacterium present at the sourrounding sediment. This process would take place during Pleistocene-Holocene epochs.