The studies concern ing longshore drift carried out on Pisa coast go back to the end of Seventies and are antecedent to the construction of most part of the coastal defence systems. The subsequent construction of protection structures has probably modified coastal dynamics. Therefore, through an agreement between Provincia an d University of Pisa a multidisciplinary study has been pianned in order to define and widen the knowledge about the Pisa coasta zone. O ne of these regards the study of provenance of littoral sands by compositional analysis. The Pisa coastal area, about 26 km long, belongs to the physiographic unit comprised between Punta Bianca and Livornesi Mounts and is mainly made by sand beaches fed from north to south by Magra, Serchio, Arno and Scolmatore rivers. The last three and particu larly the Arno River feed the pisa n coast even if in an insufficient way. Beginning from the second half of the nineteenth century the Arno delta underwent rapid erosion because of severa l factors, which strongly changed sedimentary budgets. The petrography of recent sands from the Pisa coast is used to determine their provenance and thus how their longshore transport and distribution occur. In respect to previous works the step of sampling has been increased a long transects norma l to the shore up to the 10 m isobath in order to a better estimati o n of longshore behaviour. The modal analysis has allowed us to recognize two petrographic provinces, from north to the south, which reflect distinct provenances. The northern province includes lithoquartzose sands, fed largely by the Arno River and, in small quantities, by the Serchio River. The southern province consists of quartzolithic sands, less quartzose than sands belonging to the former province. The moda l analysis and the petrographical characterization of the latter indicate a northward sediment drift. These sands are perhaps supplied from Secche della Mel oria and/or from Scolmatore River. Detrital modes of the sands a long transects show some compositional changes . within a few of these, which may indicate a major complexity in longshore transport and distribution. Besides, in arder to evaluate whether the provenance of sands has changed their characteristics both in space and time, during the last 3000 yr B. P, the compositional study of sands forming the coastal dune was a Iso carried aut, sin ce coastal dune alignment represents the position of an ancient shoreline

Provenance of modern littoral sands of Pisa coast (Tuscany, Italy)

SARTI, GIOVANNI;
2007-01-01

Abstract

The studies concern ing longshore drift carried out on Pisa coast go back to the end of Seventies and are antecedent to the construction of most part of the coastal defence systems. The subsequent construction of protection structures has probably modified coastal dynamics. Therefore, through an agreement between Provincia an d University of Pisa a multidisciplinary study has been pianned in order to define and widen the knowledge about the Pisa coasta zone. O ne of these regards the study of provenance of littoral sands by compositional analysis. The Pisa coastal area, about 26 km long, belongs to the physiographic unit comprised between Punta Bianca and Livornesi Mounts and is mainly made by sand beaches fed from north to south by Magra, Serchio, Arno and Scolmatore rivers. The last three and particu larly the Arno River feed the pisa n coast even if in an insufficient way. Beginning from the second half of the nineteenth century the Arno delta underwent rapid erosion because of severa l factors, which strongly changed sedimentary budgets. The petrography of recent sands from the Pisa coast is used to determine their provenance and thus how their longshore transport and distribution occur. In respect to previous works the step of sampling has been increased a long transects norma l to the shore up to the 10 m isobath in order to a better estimati o n of longshore behaviour. The modal analysis has allowed us to recognize two petrographic provinces, from north to the south, which reflect distinct provenances. The northern province includes lithoquartzose sands, fed largely by the Arno River and, in small quantities, by the Serchio River. The southern province consists of quartzolithic sands, less quartzose than sands belonging to the former province. The moda l analysis and the petrographical characterization of the latter indicate a northward sediment drift. These sands are perhaps supplied from Secche della Mel oria and/or from Scolmatore River. Detrital modes of the sands a long transects show some compositional changes . within a few of these, which may indicate a major complexity in longshore transport and distribution. Besides, in arder to evaluate whether the provenance of sands has changed their characteristics both in space and time, during the last 3000 yr B. P, the compositional study of sands forming the coastal dune was a Iso carried aut, sin ce coastal dune alignment represents the position of an ancient shoreline
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/109288
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