The multidisciplinary analysis of the deposits outcropping in the Nuova Lam Quarry (Lucca, Central Italy) permitted a palaeoenvironmental reconstruction which differs considerably from those traditionally proposed for the continental deposits present in this area and hitherto interpreted as lacustrine. The sequence described here is interpreted as an alluvial plain deposit. Five main associations of lithofacies have been recognised and referred to different subenvironments. Backswamp deposits crop out in the basal part. They indicate the presence of ponds periodically affected by crevasse splay processes and phases of subaerial exposure, which caused the formation of immature soils. An avulsion process, which gave rise to two main fluvial channels can be detected in the uppermost part of the sequence. A new avulsion caused a return to a backswamp zone. The investigated sequence is an example of aggradation of an ancient alluvial plain under humid climatic conditions as suggested by pollen analysis. The sequence studied makes part of continental deposits whose age has long been a matter of debate. The finding of astragali of very rare Pliotragus ardeus in the first channel deposits, along with some freshwater molluscs, allows to assign the sequence studied to the Villafranchian (Middle Pliocene-Lower Pleistocene).
Sedimentological and paleontological features of an ancient alluvial plain in the Lucca Basin (Central Italy)
SARTI, GIOVANNI;ZANCHETTA, GIOVANNI;
2001-01-01
Abstract
The multidisciplinary analysis of the deposits outcropping in the Nuova Lam Quarry (Lucca, Central Italy) permitted a palaeoenvironmental reconstruction which differs considerably from those traditionally proposed for the continental deposits present in this area and hitherto interpreted as lacustrine. The sequence described here is interpreted as an alluvial plain deposit. Five main associations of lithofacies have been recognised and referred to different subenvironments. Backswamp deposits crop out in the basal part. They indicate the presence of ponds periodically affected by crevasse splay processes and phases of subaerial exposure, which caused the formation of immature soils. An avulsion process, which gave rise to two main fluvial channels can be detected in the uppermost part of the sequence. A new avulsion caused a return to a backswamp zone. The investigated sequence is an example of aggradation of an ancient alluvial plain under humid climatic conditions as suggested by pollen analysis. The sequence studied makes part of continental deposits whose age has long been a matter of debate. The finding of astragali of very rare Pliotragus ardeus in the first channel deposits, along with some freshwater molluscs, allows to assign the sequence studied to the Villafranchian (Middle Pliocene-Lower Pleistocene).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
