The Plio-Pleistocene successions of the lower Valdarno have been studi ed since the XIX century prevalently for the presence of numerous mamma] fossi! remains. Most of the previous studies focused on biostratigraphical and paleontological observations (e.g. Bossio et al. , 1993) whereas the stratigraphical and depositional aspects were only seldom investigated (Benvenuti & Dominici, 1992, Benvenuti et al., 1997). To obtain new data on these topics, the present research considers, from a multidisciplinary geologica! standpoint, some successions cropping out in the lower Valdarno between the villages ofMontopoli and Pontedera. These successions ranging in age from the Middle Pliocene and the Middle Pleistocene, are affected by important unconformity surfaces (Zanchetta et al. , 1998). One of the most important unconformity separates the middle Pliocene deposits from the Pleistocene sediments. The middle Pliocene deposits, mainly constituted by sands and bioclastic sands, are predominantly accumulated in a coastal marine-paralic environment. They record a high sedimentary ciclicity controlled by relative marine fluctuations, and thus by the subtraction or addition of accomodation space, in relation to increase or diminution of sedimentary supply. The lower Pleistocene sediments, mainly represented by clay and silty clay in the lower part of the succession and by sands and silty sands in the upper part, are stili related to a coastal marine-paralic environment. During the middle Pleistocene, a widespread continental sedimentation took piace. Two major events of fluvial erosion related to grave! bed-load rivers followed by a phase of alluvial plain aggradation in a mixed-load river type are detected. A further aim of this study is the better understanding of the stratigraphic relationships between the succession cropping out north to the Arno river, in the Lucca basin, and those surveyed south of the Amo river, in the Elsa and Era basins. The correlati o n between these successions represent matter of debate stili far to a definitive solution (Sarti et al., 200 l; Cantini et al., 2001).
New stratigraphical data and sedimentological observations on the Plio-Pleistocene deposits of the lower Valdarno (Tuscany, Italy)
RAGAINI, LUCA;SARTI, GIOVANNI
2001-01-01
Abstract
The Plio-Pleistocene successions of the lower Valdarno have been studi ed since the XIX century prevalently for the presence of numerous mamma] fossi! remains. Most of the previous studies focused on biostratigraphical and paleontological observations (e.g. Bossio et al. , 1993) whereas the stratigraphical and depositional aspects were only seldom investigated (Benvenuti & Dominici, 1992, Benvenuti et al., 1997). To obtain new data on these topics, the present research considers, from a multidisciplinary geologica! standpoint, some successions cropping out in the lower Valdarno between the villages ofMontopoli and Pontedera. These successions ranging in age from the Middle Pliocene and the Middle Pleistocene, are affected by important unconformity surfaces (Zanchetta et al. , 1998). One of the most important unconformity separates the middle Pliocene deposits from the Pleistocene sediments. The middle Pliocene deposits, mainly constituted by sands and bioclastic sands, are predominantly accumulated in a coastal marine-paralic environment. They record a high sedimentary ciclicity controlled by relative marine fluctuations, and thus by the subtraction or addition of accomodation space, in relation to increase or diminution of sedimentary supply. The lower Pleistocene sediments, mainly represented by clay and silty clay in the lower part of the succession and by sands and silty sands in the upper part, are stili related to a coastal marine-paralic environment. During the middle Pleistocene, a widespread continental sedimentation took piace. Two major events of fluvial erosion related to grave! bed-load rivers followed by a phase of alluvial plain aggradation in a mixed-load river type are detected. A further aim of this study is the better understanding of the stratigraphic relationships between the succession cropping out north to the Arno river, in the Lucca basin, and those surveyed south of the Amo river, in the Elsa and Era basins. The correlati o n between these successions represent matter of debate stili far to a definitive solution (Sarti et al., 200 l; Cantini et al., 2001).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
