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Geo4P - Geothermal Pilot Project Pisan Plain: quantitative assessment of very low, low and medium temperature shallow geothermal resources

European Geothermal Congress 2016
Strasbourg, France, 19-24 Sept 2016
Geo4P - Geothermal Pilot Project Pisan Plain: quantitative assessment of very
low, low and medium temperature shallow geothermal resources
Alessandro Sbrana1, Giuseppe Pasquini1, Paola Marianelli1, Dario Bonciani2, 3 and Loredana
Torsello2, 3
1 University of Pisa, Dipartimento di Scienze della Terra, via Santa Maria 53, 56126, Pisa, Italy
2 EnerGea, via G.Carducci 4, 56044, Larderello (PI), Italy
3Co.Svi.G. via T. Gazzei 89, 53030, Radicondoli (SI), Italy
Keywords: geothermal exploration, 3D modelling,
Pisan plain, renewable heating and cooling,
multidisciplinary approach.
This paper presents the first results of an integrated
geothermal research project. Geo4P (Geothermal
Pilot Project Pisan Plain) is started in July 2014 for the
development of a multidisciplinary methodology,
aimed at carrying out a quantitative assessment of low
temperature shallow geothermal resources in Pisa
plain. The ultimate aim is to produce a tool useful to
enhance the use of geothermal heat pumps in heating
and cooling plants, for public utilities. Concerning
geological and geothermal researches, 3D integrated
subsoil models are produced within Geo4P, whereas
3D results are implemented in thermo-fluid dynamic
simulations in order to increase the thermal knowledge
of the subsurface.
The aim of this project is to develop an innovative
multidisciplinary approach, including geological,
geochemical, geophysical and numerical modelling,
for assessment of low temperature geothermal
potential of the Pisan plain. Despite the existence of
many information and many data have already been
collected in the past, all the investigation elements
took into account by this Project are not always treated
in a systematic way and made easily accessible. In
addition difficulties are encountered within local
authorities, which does not always have appropriate
tools for a proper use of local resources.
The Geo4P Project is therefore mainly aimed at
supporting public and private players potentially
interested in considering the opportunities offered by a
more efficient development of shallow geothermal
The studied area includes the municipalities of
Vecchiano, San Giuliano Terme, Calci, Buti, Bientina,
Vico Pisano, Calcinaia, Pisa, Cascina, Pontedera,
Fauglia, Crespina Lorenzana, Casciana Terme Lari
and Ponsacco and it covers more than 570 Km2 (Fig.
The project is developed on the following steps:
research and collection of existing data from
different sources,
creation of a geographical information system
for data storage, management and updating,
data validation and analysis and interpretation
to obtain a geothermal conceptual model,
3D geological modelling,
surveys for collection of geothermal chemical
and physical subsoil parameters,
thermofluidodynamic 3D modelling
recommendations to local decision makers
and presentation of project results to local
Figure 1: The studied area.
Sbrana et al. 2016
The Pisa plain is located in Nord West side of
Tuscany region and is mainly made up of
neoautochtonous deposits that fill a wide graben
striking NW-SE (Bellani et al 1995). The coastal plain
is bounded by the Pisa Mountains to the Northeast, the
Leghorn and Pisa hills to the South, and the
Tyrrhenian Sea to the West (Sarti et al 2012).
Because of tectonic and climatic events, sediments
were deposited on the rock substratum from Miocene
to Quaternary. After two major transgressive cycles
(Upper Miocene, Lower Pliocene), which led to the
deposition of conglomerates, sands, clay and
evaporitic sediments, an important regressive phase
ensued during the Middle Pliocene. This brought
about land emergence and widespread erosional
activity (Grassi and Cortecci 2005). During the
Pleistocene there were several eustatic fluctuations
and the sediments were deposited in the area
according with the flooding stage of Arno-Serchio
water system. Then (Upper Pleistocene Holocene),
mainly fluvial and marshy sediments were deposited,
due to reduced fluvial activity linked to both the
eustatic sea-level lowering and progressive drying of
the climate (Grassi and Cortecci 2005).
The historical evolution of Pisa plain results in a
complex stratigraphic pattern: the generally accepted
hydrogeological scheme (Trevisan and Tongiorgi
1953; Dini 1976; Fancelli 1984, Baldacci et al 1994;
Rossi and Spandre 1994) is that there is a multi-
layered confined aquifer (MCA) system with two
major confined aquifers, locally connected.
The first step of the project was to research and collect
all available information on Pisa basin evolution:
geology, stratigraphy, hydrogeology, chemical and
isotopic analysis of aquifers. All data were collected in
a dedicated geo-database developed on Esri ArcGis
10.2.2. Gis structure reflects the following scheme
(Fig 2) and is organized in 5 information layers
(shapefiles) mutually connected to each other from the
key field “identifies”.
Figure 2: DB setting with Informative Layers
The Geographical Information System also contains
raster elements:
Geomorphologic map of Pisa (Cerratori et al
Geological map of Tuscany, sheet 273, Pisa
Section 273010, scale 1: 10.000 (ISPRA),
Rocks permeability map, Aquifer System of
Pisa plain (Baldacci et al 1998),
Geological Map of the North-western part of
Pisa Mountain, scale 1: 25.000 (Giannini and
Nardi 1964),
II interpretative geological map of the Pisan
hills to the Southeast of the Guappero Valley,
scale 1: 25.000 (Rau and Tongiorgi 1974),
Topographic map in scale 1: 10.000
Digital elevation model (DEM) of the area,
cell size 20m.
All data were georeferenced in
WGS_1984_UTM_Zone_32N (WKID 32632)
coordinate system.
3.1 Informative layer IL_001_Wells
IL_001_Wells” contains all the available information
regarding 2740 water wells and geotechnical surveys
(Fig 3) in the area of study: latitude, longitude,
altitude, depth and data source.
Sbrana et al. 2016
Figure 3: IL_001_Wells; features are coloured
according to the depth of survey, hot colours
for deeper wells.
3.2 Informative layer “IL_002_Stratigraphy
IL_002_Stratigraphy contains the stratigraphic
description for each survey. Each point represents a
lithological layer (Fig 4).
Figure 4: IL_002_Stratigraphy.
3.3 Informative layer “IL_003_Temperature
“IL_003_Temperature collect 193 temperature
measures (Fig. 5): these data come from bibliographic
sources and fieldwork survey that interested 97 wells
between 2015 and 2016. Temperature values are
associated, where is possible, with the filter depth.
Figure 5: IL_003_Temperature.
3.4 Informative layer “IL_004_Hidrogeology
“IL_004_Hydrogeology” holds 1449 elements (Fig. 6)
and manages the hydrogeological information like
permeability, transmissivity, flow rate, storage coefficient,
number and depth of filters in wells.
Figure 6: IL_005_Hydrogeology.
3.5 Informative layer “IL_005_Water_chemistry”
“IL_005_Water_chemistry” contains chemical results
of water analysis from bibliography and from field
sampling during the last year (Fig. 7). Light blue
points represent sampling taken during this project and
subjected to chemical and isotopic analysis.
Figure 7: IL_005_Water_chemistry. The map
shows the wells for which you have the
results of chemical analysis.
Chemical analysis results (Fig. 8) and isotopic survey
will be useful to improve the knowledge of
underground circulation in aquifers.
Sbrana et al. 2016
Figure 8: Piper diagram for chemistry
classification of Pisan plain underground
4.1 Hydrogeological conceptual model
According with existent bibliography (Baldacci et al
1994, Sarti et al 2012, Grassi and Cortecci 2005.) and
using database information, a 3D hydrogeological
model of Pisan plain was set. The model realization
was carried out through a series of operations that
allowed extending punctual information to the whole
studied area. The hydrogeological interpretation of
significant stratigraphy and the creation of 16
hydrogeological sections provided the characterization
of following hydrogeological units:
Recent Alluvial Cover: clays and
discontinuous sand bodies, related to recent
Arno and Serchio flooding deposits, host
suspended aquifers with low flow rates;
Multilayer Confined Aquifer (MCA): is
composed by 2 permeable levels with sands
and gravels, locally connected. It hosts
aquifers with high flow rates;
Clay 1: where it exists, separates the
permeable horizons of MCA System.
Clay 2: clayey sediments below MCA
Coastal Dune Aquifer: eolian and marine
sand deposits. It extends from the coast to the
western side of Pisa. This aquifer is locally
connected with MCA.
Alluvial Fans Aquifer: dense succession of
gravelly deposits that move from Pisan
mountains to Arno valley. It hosts several
spring and high water circulation.
4.2 Petrel workflow for model creation
Modelling process was performed with Petrel E & P
Software Platform, Version 2013.6, using the
following input data:
450 wells (Fig. 9 and Fig. 10), selected
considering depth and quality of information.
For each well, hydrostratigraphic units top
(“well top”), was located (Fig. 11),
16 hydrological sections (Fig. 12). For each
section were located points (“additional
points”) matching with the top of
hydrostratigraphic units,
Petrel has processed well tops and additional
points, building the surfaces of the different
units to be modelled. The interpolation was
led by “convergent interpolation algorithm”
generating regular mesh grids, 50x50 m. The
surfaces were further refined by the operator
where software performed anomalous or
irregular results (Fig. 13),
Bedrock top surface was obtained by
inversion of gravimetric measures (Fig. 14),
Finally, starting from surfaces, a complete 3D
hydrogeological underground model of Pisan
plain was built (Fig. 15, Fig. 16, Fig, 17).
Sbrana et al. 2016
Figure 9: Wells imported in Petrel project, in studied area.
Figure 10: Wells in Pisa city.
Figure 11: Well tops in Pisa city area.
Sbrana et al. 2016
Figure 12: Hydrogeological sections imported in Petrel project, in studied area.
Figure 13: Obtained surfaces, in Pisa city area.
Figure 14: Bedrock, top surface.
Sbrana et al. 2016
Figure 15: 3D hydrogeological underground model of Pisan plain.
Figure 16: EW model section.
Figure 17: NS model section.
Sbrana et al. 2016
A portion of the hydrogeological model was imported
in PetraSim 5, RockWare software with graphical
interface for the TOUGH2 family of simulators.
(Fig.18, Fig.19, Fig. 20). Values of density,
permeability, porosity, conductivity and specific heat
were associated to single hydrostratigraphic units.
The top of model, has been set with a temperature of
16°C (mean value of atmospheric temperature in
Pisa). For the bottom of the model, represented by
bedrock surface, were used temperature values
variable, according with the depth and with the local
geothermal gradient.
Figure 18: Surfaces imported in PetraSim 5.
Figure 19: Hydrogeological model in PetraSim 5.
Figure 20: Layers volumes were divided in regular
cells on XY plane (500x500 m).
5.1 Simulation results
The simulation distributes temperature values on all
the cells of model (Fig.21, Fig.22), according with
initial condition and with the lithological and
geothermal properties of sediments.
Figure 21: Temperature results, interpolated at
specified horizontal slice. In blue cold
temperature, in yellow hottest sectors.
Figure 22: Temperature results. The upper blue
surface describes the trend of 20°C isotherm.
The horizontal slice below represents
temperature values at -200m of depth. The
vertical slices show the complete
temperature range from the top to the
bottom of the model.
Temperatures in the middle of upper Multilayer
Confined Aquifer level were extracted from this
model (Fig. 23 and Fig. 24). Obtained results are
comparable with the temperature collected during
field surveys.
Sbrana et al. 2016
Figure 23: temperature interpolation simulated at the middle of upper MCA level. The hot colours represent
areas with higher temperatures. South view.
Figure 24: temperature interpolation simulated at the middle of upper MCA level. The hot colours represent
areas with higher temperatures. Southwest view.
As well as giving information about the shallow
geothermal potential of the whole study area,
geological results so obtained will be used to suggest
best suitable technologies to use locally available
geothermal heat, also taking into account specific
users features and requirements. These plant solutions
will be indeed identified taking into account the
sustainable use of geothermal resources, both under
the economy related issues and the environmental
point of view, avoiding negative impacts in shallow
Project results will be particularly helpful in case of
integration into urban plans and/or local energy plans.
Municipalities will thus be able to better support their
decision-making processes, the preparation of
datasheets in SEAPs or other local energy planning
tools, thanks to the use of results obtained by the
Geo4P Project.
In a time when public acceptance towards geothermal
projects the involvement of territories involved in the
project has not been overlooked. Local decision
makers and technicians of municipalities are indeed
being involved, proposing them useful
recommendations to allow the promotion of
appropriate local energy planning tools and to foster
Sbrana et al. 2016
appropriate activities for the use of geothermal
resources. Project results will also be made available
to citizens and companies who intend to take into
account geothermal resources for thermal uses and to
produce cool, with economic and environmental
Once the multidisciplinary methodology for the
Geo4P project will be validated, as well as promoting
sustainable energy consumption in territories of the
Pisan plain, through the use of shallow geothermal
resources, it will be made available to stakeholders.
This will allow to export and implement these geology
and energy related analysis techniques in similar
contexts. The Pisan plain is indeed a typical example
of alluvial plain, as many others in Italy and Europe.
Projects results will be published by the second half of
2016 at the following web address:
Aguzzi M., Amorosi A. and Sarti G., Stratigraphic
architecture of late quaternary deposits in the
lower Arno plain (Tuscany, Italy), Geologica
Romana, 38, (2005), 1-10.
Aguzzi M., Amorosi A., Castorina F., Ricci Lucchi
M., Sarti G. and Vaiani C.: Stratigraphic
architecture and aquifer systems in the eastern
Valdarno Basin, Tuscany, Geoacta, 5, (2006), 39-
Amorosi A., Lucchi M.R., Rossi V. and Sarti G.:
Climate change signature of small-scale
parasequences from Lateglacial-Holocene
transgressive deposits of the Arno valley fill,
Paleogeography, Paleoclimatology,
Palaeoecology, 273, (2009), 142-152.
Bellani, S., Grassi, S. and Squarci, P.: Geothermal
characteristics of the Pisa plain, Italy.
Proceedings of the World Geothermal Congress.
May18311995, Florence, Italy, (1995), 1305
Butteri M., Doveri M., Giannecchini R. and Gattai P.:
multidisciplinary study of the confined gravelly
aquifer in the coastal Pisan Plain between the
Arno River and the Scolmatore Canal, Memorie
Descrittive della Carta Geologica d’Italia, XC,
(2010), 51-66.
Federici P.R., Mazzanti R.: L’evoluzione della
paleogeografia e della rete idrografica del
Valdarno inferiore, Bollettino della Società
Geologica Italiana, Ser. XI, vol. V, Roma,
(1988), 573-615.
Grassi S. and Cortecci G.: Hydrogeology and
geochemistry of the multi-layered confined
aquifer of the Pisa plain (Tuscany-central Italy),
Applied Geochemistry, 20, (2005), 41-54.
Sarti G., Rossi V. and Amorosi A.: Influence of
Holocene stratigraphic architecture on ground
surface settlements: A case study from City of
Pisa (Tuscany, Italy), Sedimentary Geology, 281,
(2012), 75-87.
Tongiorgi M., Rau A., and Martini I.P.:
Sedimentology of early-alpine, fluvio-marine,
clastic deposits (Verrucano, Triassic) in the Monti
Pisani (Italy), Sedimentary Geology, 17, (1977),
Geo4P was developed within the Memorandum of
understanding among the following Organizations:
Italian Ministry of economic development (UNMIG),
Regional Government of Tuscany, Province of Pisa,
Consortium for the Development of Geothermal
Areas, University of Pisa, Sant’Anna School of
Advanced Studies, EnerGea, Acque and AEP. This
Project is financed by the Geothermal Fund, through
the “General Agreement on Geothermal”, signed by
the Tuscany Region, Enel Green Power,
municipalities of Tuscan geothermal areas, their
unions and provinces of Grosseto, Pisa and Siena and
CoSviG. The Geothermal Fund collects economic
compensations that geothermal territories receive from
Enel Green Power for the use of geothermal resources.
... Gravel Fans Unit (GFU): a succession of continental gravel deposits with interlayers of minor clay-rich sediments that stretch from the Monte Pisano fans to the Pisa plain [42]. This highly permeable unit hosts several springs [33,43,44] and is a recharge area for the aquifers of the alluvial-sedimentary plain. The lithostratigraphic correlations of wells and sections allowed synthesis of the conceptual geological/hydrogeological model illustrated in Figure 3. ...
... Gravel Fans Unit (GFU): a succession of continental gravel deposits with interlayers of minor clay-rich sediments that stretch from the Monte Pisano fans to the Pisa plain [42]. This highly permeable unit hosts several springs [33,43,44] and is a recharge area for the aquifers of the alluvialsedimentary plain. ...
... Clay and Sands Unit (CSU): clayey and sandy sediments below the SGU. Just a few deep boreholes intercept this unit [44]. ...
Full-text available
Shallow, low-temperature geothermal resources can significantly reduce the environmental impact of heating and cooling. Based on a replicable standard workflow for three-dimensional (3D) geothermal modeling, an approach to the assessment of geothermal energy potential is proposed and applied to the young sedimentary basin of Pisa (north Tuscany, Italy), starting from the development of a geothermal geodatabase, with collated geological, stratigraphic, hydrogeological, geophysical and thermal data. The contents of the spatial database are integrated and processed using software for geological and geothermal modeling. The models are calibrated using borehole data. Model outputs are visualized as three-dimensional reconstructions of the subsoil units, their volumes and depths, the hydrogeological framework, and the distribution of subsoil temperatures and geothermal properties. The resulting deep knowledge of subsoil geology would facilitate the deployment of geothermal heat pump technology, site selection for well doublets (for open-loop systems), or vertical heat exchangers (for closed-loop systems). The reconstructed geological-hydrogeological models and the geothermal numerical simulations performed help to define the limits of sustainable utilization of an area's geothermal potential.
Full-text available
Developing a realistic model of high-resolution stratigraphy from the subsurface of modern alluvial and coastal plains is an important first step toward a successful three-dimensional representation of aquifers and aquifer systems. An integrated (stratigraphic, sedimentological and micropalaeontological) study of six cores, 100-115 m long, from the eastern Valdarno Basin, Tuscany, enables the detailed reconstruction of Pliocene to Quaternary subsurface architecture between Pontedera and S. Croce sull'Arno. Pollen data from lagoonal sediments and strontium isotope dating of shallow-marine deposits provide the basis for the construction of a reliable chronologic framework for the study succession. Stratigraphic correlations, based upon detailed facies anal ysis, show a varied facies architecture in the study area. Beneath the Holocene succession, which is about 40 m thick and consists of alluvial deposits resting onto transgressive swamp clays, pre-Holocene deposits display remarkably different characteristics from Pontedera toward the basin margin, likely as a result of tectonic activity due to a normal fault running parallel to the Apenninic chain. In the Pontedera area, a thick succession of Pleistocene alluvial deposits, showing a cyclic alternation of fluvial-channel (gravel/sand) and floodplain (clay) facies associations is the dominant stratigraphic feature. By contrast, lower-middle Pliocene deposits, characterized by alternating coastal and shallow-marine deposits, with very subordinate alluvial facies, are recorded at shallow depths, west of S. Croce. A significantly improved stratigraphic architecture in the uppermost 100 m enables detailed reconstruction of aquifers geometry in the eastern Valdarno Basin. With respect to previous work, documenting the presence of one aquifer only, a multilayered confined aquifer, made up of five aquifer systems ranging in age from Middle Pliocene to Holocene, is identified in this study. Lenticular and sheet-like geometries of these aquifer systems are reconstructed, as a function of the alluvial versus littoral origin of their constituent deposits. According to the geological framework, the Pliocene to Quaternary sands cropping out on the Pisa Hills are likely to represent the meteoric-water recharge area for the aquifers of the eastern Valdarno Basin.
Full-text available
Detailed sedimentological investigation of two continuously-cored boreholes, up to 106 in deep, combined with stratigraphic analysis of about 300 well logs performed for water research in the area between Cascina and the Tyrrhenian coast, reveal subsurface stratigraphy of Late Quaternary deposits in the lower Arno Plain. Facies analysis of the cores allows identification of twelve different facies associations, grouped into alluvial and coastal depositional systems. A stratigraphic cross section, roughly parallel to present Arno River and 30 km long, shows the presence of two trangressive-regressive sequences, attributed to the last two interglacial-glacial cycles (base of OIS 1 and 5e, respectively). Despite significant facies variability from proximal to distal locations, the basal transgressive surfaces appear as the most readily identifiable features from both core and borehole data, and constitute a stratigraphic marker that can be physically traced across the entire study area. The high resolution stratigraphic data shown in this paper are in marked contrast with previous work, and provide a new stratigraphic framework for the upper portion of the Viareggio Basin.
Full-text available
Despite recent report of short-term cyclicity from Lateglacial–Holocene deposits of several coastal plains worldwide, no precise documentation of the key factors controlling cyclic facies architecture has been made available by previous work.Detailed sedimentological analysis of a continuously-cored borehole, around the town of Pisa, in western Tuscany, provides evidence for the occurrence of three high-frequency, transgressive–regressive cycles within the post-Last Glacial Maximum (LGM) transgressive succession (13–8 cal. kyr BP) of the Arno incised-valley fill. These cycles, which are bounded by lateral equivalents of marine flooding surfaces, are 8–12 m thick and correspond to small-scale parasequences. Micropalaeontological (foraminifers and ostracods) investigations based upon differentiation of eight microfossil associations, allow to refine the stratigraphic framework, emphasizing subtle changes in palaeosalinity across parasequence boundaries.Diagnostic changes in vegetation patterns, driven by opposite climate conditions, enable precise documentation of parasequence development as a function of climate change. Pollen spectra invariably show expansions of broad-leaved forests at parasequence boundaries, suggesting that rapid shifts to warmer climate conditions accompanied episodes of rapid sea-level rise. In contrast, stillstand phases saw the development of cold-temperate communities (upper parts of parasequences), suggesting transition to temporary colder climate conditions.Reconstruction of parasequence architecture on the basis of adjacent stratigraphic data, combined with palaeoclimate characterization and radiometric dating enable identification, within the transgressive Arno valley body, of three major “regressive” pulsations that are tentatively correlated with the most important cooling events of the post-LGM period. The sedimentary response to these short-term phases of climatic cooling is clearly documented by episodes of widespread coastal-plain and bay-head delta progradation, leading to partial estuary infilling and temporary establishment of continental environments in the proximal and central sectors of the valley.
The Holocene stratigraphic architecture of modern coastal and deltaic plains has peculiar characteristics that may influence ground surface settlements. In the Pisa urban area, the inhomogeneous spatial distribution of geotechnically weak layers, typically formed during the mid–late Holocene (highstand) coastal progradation, is inferred to be responsible for urban ground settlement and building damage, as evidenced by the tilt of several surface structures, among which the famous Leaning Tower of Pisa is the most prominent. On the basis of integrated stratigraphic, sedimentological and geotechnical data from a wide georeferenced database, three facies associations with high deformability potential (Units 1–3) are identified in the uppermost 30 m as opposed to depositional facies (Units 4–5) with higher geotechnical strength. Whereas Unit 1 represents a thick, laterally extensive lagoonal clay deposit, the overlying highly deformable units (Units 2–3) show more discontinuous spatial distribution controlled by the Holocene paleohydrographic evolution of the Arno coastal plain. Unit 2, dated between the Neolithic and the Etruscan age (ca. 5000–2000 yr BP), is composed of swamp clays and silty clays recording lagoon infilling due to Arno Delta progradation. Units 3 and 4, which consist of wet levee deposits and stiff floodplain clays, respectively, formed during the subsequent phases of alluvial plain construction started around the Roman age (from ca. 2000 yr BP). Whereas Units 3 and 4 are recorded within the uppermost 5 m, fluvial and distributary channel sands (Unit 5) cut the underlying deltaic–alluvial succession at various stratigraphic levels, down to Unit 1. The spatial distribution of these units gives rise to three, locally juxtaposed, stratigraphic motifs in Pisa underground, reflecting different potential risks for settlement under building loads. We show how lateral changes in stratigraphic architecture account for the irregular spatial distribution of geotechnically weak layers that are responsible for building damage and ground settlement.
The Pisa plain contains a multilayered confined aquifer made up of Pleistocene sands and gravels. The groundwater from the wells tapping these horizons are generally of poor quality: they exhibit significant TDS, relatively high Cl content and considerable hardness. During geothermal prospecting of the Pisa plain, about 80 wells ranging in depth from 20 to 250 m were sampled, and both chemical (major ions) and isotope analyses were conducted. The data collected show that TDS is strongly influenced by HCO3 and Cl, and that a 3-component mixing process affects the groundwater’s chemical composition. The end members of this mixing process have been identified as: (a) diluted HCO3 meteoric water, which enters the plain mainly from the eastern and northern sides of the study area; (b) Cl-rich water, which largely characterizes the shallow sandy horizons of the multilayered aquifer system and has been attributed to the presence of seawater, as also suggested by δ18O data; and (c) SO4-rich groundwater, which is linked to the hot groundwater circulation within Mesozoic carbonate formations and, at first sight, seemed to affect only the gravelly aquifer. A SO4-rich water also contributes to the sandy aquifer; it probably enters the plain both laterally, from the margins of the Pisan Mountains and from depth, but promptly undergoes substantial SO4 reduction processes by bacteria. That such processes are at work is suggested both by the low SO4 and high HCO3 concentrations found in the well waters and by their C and S isotope compositions. The collected data have allowed zones with higher quality waters to be identified, which may someday be used for the local water supply.
The sedimentological investigation of the Middle and lower Upper Triassic clastic rocks of the Mt. Pisani, Tuscany, Italy (type locality of the Verrucano) indicates three main depositional sequences that constitute a fluvio-deltaic shelf complex.The lower fluvial sequence is characterized by an upward transition from conglomeratic deposits of braided streams to sandy, shaly deposits of low- and high-sinuosity meandering streams. In the top part of the fluvial sequence, within the cyclic deposits of these meandering rivers, several types of channel fills are to be found. Some are of the point-bar type, others are due to deposition predominantly in transverse bars of crossover reaches; others are characterized by a highly variable texture and trough cross-bedding that are typical of the braided reaches of streams. The fine overbank interlayers of these meandering braided streams are usually capped by caliche profiles.The intermediate, fossiliferous, shelf sequence was formed in a wide, shallow shelf, locally and temporarily barred by sand ridges, and swept by seasonal storms. Several sedimentological sequences developed, such as wavy and lenticular beds, structureless storm layers, thin fining-upward ‘tidalites’ and shallow-water turbidites. The deposits of the bars show distinct traces of inclined accretionary surfaces and thin planar cross-beddings that indicate upslope migration of secondary longitudinal sand ridges.The sedimentary cycle is closed by a prograding deltaic sequence that grades from delta-front sand to silt and clay of deltaic plain-bays. Extensive and regular sandstone beds, coarsening-upward bar sequences and shallow, wide channel fills all characterize submerged parts of the delta. Thick, coarse-grained deposits of distributary channels, thin silt—shale interlaminations of flood plains and bays, well-developed thickening-upward sequences of crevasse—splay deposits, mud cracks and tracks of tetrapods are the most typical features of the deltaic plain.This Triassic sedimentary system developed during early rifting stages of the Alpine geosyncline. The active tectonic regime and related morphological rejuvenation of the lands are recorded in repeated interfingering of facies and in the reappearance of fresh Hercynian materials at different stratigraphic levels.
Hydrogeologic-hydrogeochemical multidisciplinary study of the confined gravelly aquifer in the coastal Pisan Plain between the Arno River and the Scolmatore Canal, Memorie Descrittive della Carta Geologica d'Italia, XC
  • M Butteri
  • M Doveri
  • R Giannecchini
  • P Gattai
Butteri M., Doveri M., Giannecchini R. and Gattai P.: Hydrogeologic-hydrogeochemical multidisciplinary study of the confined gravelly aquifer in the coastal Pisan Plain between the Arno River and the Scolmatore Canal, Memorie Descrittive della Carta Geologica d'Italia, XC, (2010), 51-66.
L'evoluzione della paleogeografia e della rete idrografica del Valdarno inferiore
  • P R Federici
  • R Mazzanti
Federici P.R., Mazzanti R.: L'evoluzione della paleogeografia e della rete idrografica del Valdarno inferiore, Bollettino della Società Geologica Italiana, Ser. XI, vol. V, Roma, (1988), 573-615.