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Considerazioni preliminari sulla paleogeografia del dominio toscano interno tra il Trias superiore ed il Miocene medio
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Stable water isotope as foundamental tool in karst aquifer studies: some results from isotopic applications in the Apuan Alps carbonatic complexes (NW Tuscany)
Full text linkThe management and protection of water resources in karst environment require detailed knowledge of the aquifer system which can be obtained through a multidisciplinary approach, including not only hydrogeological/structural assessment, but also the use of tools not commonly used in hydrogeology, as the isotope ratios.
In the present work some examples of isotopic applications on karst aquifers are discussed in relation to hydrogeological studies carried out in the Carrione Stream, Frigido River, and Versilia River catchments (Apuan Alps, Tuscany). In particular, during such studies the isotopic ratios 18O / 16O and 2H / 1H of the water molecule, mainly, and 13C / 12C of inorganic carbon in solution were used.
The isotopic data, and their comparison with the hydrogeological and structural-geological ones, were useful: to obtain information about the hydrodynamic conditions in the aquifer; to define the recharge area of main springs; and to identify different circulation systems drained by closing springs which have similar chemistry.
The obtained results confirm that in karst systems, where it is often difficult to carry out conventional hydrogeological surveys, the isotopic instruments have a fundamental role in the study of water circulation
Note Illustrative del Foglio 217 Neviano degli Arduini della Carta Geologica d'Italia a scala 1: 50.000
No full textI depositi Del Pleistocene inferiore della Bassa val Di Cecina (Toscana, Italia): ricostruzione stratigrafico-deposizionale e proposta di suddivisione in unità allostratigrafiche
No full textIn the area comprised between the villages of Riparbella and Casale Marittimo (lower Cecina Valley, Tuscany, Italy) a large amount of
Pleistocene deposits outcrops. Through a detailed geological survey integrated with facies analysis five litostratigraphic units, grouped
in three Allostratigraphic Units (UA), have been detected. The oldest (UA7), lower pleistocenic in age, is formed by two litostratigraphic
units (“Conglomerati delle Ginepraie” and “Sabbie ed argille ad Arctica islandica”) showing latero-vertical relationships and are organized
in a transgressive-regressive cycle. The “Conglomerati delle Ginepraie” are arranged in a fining upwards trend and were deposited
in small coalescent deltaic environments. Three depositional facies are recognized within the “Sabbie ed argille ad Arctica islandica”
recording a fining-coarsening and deepening shallowing upward trend. The UA7 lies in unconformity above pre-quaternary deposits.
The second (UA6), lower pleistocenic in age, is also constituted by two heteropic and transgressive litostratigraphic units
(“Conglomerati delle Lame” and “Arenarie e Sabbie di Montescudaio”) lying in angular unconformity on the UA7. The “Conglomerati
delle Lame”, showing a well developed imbrication, were deposited in a foreshore to upper shoreface depositional environment. The
“Arenarie e Sabbie di Montescudaio” are characterized by a high to low planar-cross stratification and sometimes by overturned stratification
and were deposited in a shallow marine environment. The regressive phase of this UA is not preserved due to erosive processes.
The youngest unit (UA4, “Conglomerati di Serra all’Olio”), was instead deposited in fluvial-braided environment and lies in angular
unconformity on the others UA. The middle pleistocenic age of this unit has been inferred on the basis of its stratigraphic position. This
stratigraphic reconstruction strongly conflict from previous interpretations. Important climatic and geological remarks derive from the
finding of two taxa (Arctica islandica and the coral Cladocora caespitosa) at different stratigraphic positions within the oldest unit
(“Sabbie ed argille ad Arctica islandica”). The Arctica islandica testifying cold temperatures (4°C to 13°C) characterizes the first 5
meters of the unit, while beds of Cladocora caespitosa (15°C to 22°C the temperature range of this coral) only occur upwards. We
retain that the deposition of the “Sabbie ed argille ad Arctica islandica” takes place during a warming phase and that the development
of Cladocora caespitosa beds could be related to the maximum flooding conditions at the end of the transgressive phase. This interpretation
leads to some notable chronostratigraphic implications
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