Variaciones mineralógicas en sedimentos de la llanura aluvial del río Paraná Medio

E. PASSEGGI

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 1996 vol. 51 p. 156 - 164

1853-7138

Themineral composition of river bed sedimentsas evaluated for three secondarychannels of differing hierachy within the middle Paraná river floodplain. They were compared with that of the main channelin order to detect possible compositional modifications. Although no markedqualitative variations were found, some significant changes in the mineralproportions were observed. Mineralogical maturity was greatest in the mainchannel and decrease towards the lower hierarchy, secondary floodplainsstreams, as shown by the increase of feldspar (plagioclase) percentage within thelight mineral fraction. Among the heavy minerals, opaques, zircon and rutileincreased form the main channel to the secondary channels with a correspondingdecrease in the assemblage kyanite-tourmaline-staurolite-garnet. This probablyoccurred as a result of the progressive sorting related to textural variationsin these fluvial sediments.