STRATIGRAPHIC ARCHITECTURE OF LATE QUATERNARY DEPOSITS IN THE LOWER ARNO PLAIN (TUSCANY, ITALY)

Margherita Aguzzi*, Alessandro Amorosi* & Giovanni Sarti**

*Dipartimento di Scienze della Terra e Geologico-Ambientali, Università di Bologna, Via Zamboni 67 - 40126 Bolognae-mail: amorosi@geomin.unibo.it

**Dipartimento di Scienze della Terra, Università di Pisa, Via Santa Maria 53 - I-56126 Pisa

INTRODUCTION

The Arno coastal plain, bounded by the Versiliacoastal plain and Pisani Mountains to the north, and Pisaand Leghorn hills to the south (Fig. 1), constitutes thesouthern, inshore portion of the wider Viareggio Basin(Nagi & Pascucci, 2002), corresponding to the Pisa-Versilia Basin of Mazzanti (2000). This sedimentarybasin represents the infill of a half-graben system(Mariani & Prato, 1988; Nagi & Pascucci, 2002) thatformed along the Tyrrhenian margin since the LateTortonian, in response to the opening of the TyrrhenianSea and the counter-clockwise migration of the chain-foredeep-foreland system (Malinverno & Ryan 1986;Sartori, 1989; Patacca et al., 1990; Martini & Sagri,1993; Meletti et al., 1995; Pascucci et al. 2001). ThePisa-Versilia Basin includes a remarkably thick (up to3800 m) succession of Neogene to Quaternary deposits,which are subdivided into a series of seismo-stratigraph-ic sequences (Mariani & Prato, 1988; Nagi & Pascucci,2002). The Pleistocene sequence, which is deeply fault-ed with the exception of its uppermost portion (Argnaniet al., 1997), consists of two sub-units (sequences I andII of Mariani & Prato, 1988, and 6a and 6b of Nagi &Pascucci, 2002).

The few studies available about subsurface stratigra-phy of the Arno coastal plain have been finalized most-ly to hydrogeological research (Baldacci et al., 1995;Baldacci, 1999). The dataset includes almost exclusive-ly logs from boreholes drilled for water research purpos-es, with scarce detailed stratigraphic, sedimentologicaland chronologic information. Present knowledge of sub-surface stratigraphy in the Arno coastal plain, thus, gen-erally relies upon stratigraphic interpretations of poor-quality data, with scattered high-resolution stratigraphic

analyses only (Gioli, 1894; Trevisan & Tongiorgi, 1953;Romagnoli, 1957; Mazzanti, 1983; Sartori, 1978;Baldacci et al., 1995; Della Rocca et al., 1987; Marroniet al., 1990; Mazzanti, 1994; Federici & Mazzanti 1995;Mazzanti, 2000).

An overall picture of subsurface stratigraphy in theArno coastal plain has been provided by Fancelli et al.(1986). On the basis of stratigraphic data from previous-ly described boreholes (Ghelardoni et al., 1968), theseauthors subdivide the Quaternary succession of the ArnoPlain into three tectono-stratigraphic units. The upperunit (substrato superiore), the age of which is youngerthan early Pleistocene, is made up of an alternation offine-grained and coarse-grained sediments, which can besummarized, from bottom to top, as follows:

Shallow-marine clays and sands. This unit has beenidentified at Bigattiera (Sartori 1978) and Saint Gobain(Romagnoli, 1957) boreholes (Fig. 1), between 100 mand 86 m below sea level. It has been attributed to theearly Pleistocene (Fancelli et al., 1986), although a mid-dle Pleistocene age has been suggested by Della Roccaet al. (1987).

Arno and Serchio da Bientina conglomerates. Thisunit was first defined by Segre (1955), and has beeninterpreted to represent a lithologic marker-bed acrossthe whole Arno coastal plain, for both stratigraphic andhydrogeologic purposes (Baldacci et al., 1995). Depthcontours of the bottom of this lithostratigraphic unit,ranging between 15 and 145 m below sea level, depict acomplex paleo-topography, suggesting the presence ofan incised valley (Fancelli et al., 1986; Della Rocca etal., 1987). The Arno and Serchio da Bientina conglom-erates have been correlated, for long time, to Würm II(Ghelardoni et al., 1968; Barsotti et al., 1974; Fancelli etal., 1986; Della Rocca et al., 1987; Federici & Mazzanti,

Geologica Romana 38 (2005), 1-10

ABSTRACT - Detailed sedimentological investigation of two continuously-cored boreholes, up to 106 m deep,combined with stratigraphic analysis of about 300 well logs performed for water research in the area betweenCascina and the Tyrrhenian coast, reveal subsurface stratigraphy of Late Quaternary deposits in the lower ArnoPlain.

Facies analysis of the cores allows identification of twelve different facies associations, grouped into alluvialand coastal depositional systems. A stratigraphic cross section, roughly parallel to present Arno River and 30 kmlong, shows the presence of two trangressive-regressive sequences, attributed to the last two interglacial-glacialcycles (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 pro-vide a new stratigraphic framework for the upper portion of the Viareggio Basin.

KEY WORDS: transgressive-regressive cycles, facies analysis, Late Quaternary, Viareggio Basin.

1988; Marroni et al., 1990); only recently, an attributionto Würm I (OIS 4) has been proposed (Federici &Mazzanti, 1995; Mazzanti, 2000).

Fluvial and swamp silts. These deposits, which over-lie the Arno and Serchio da Bientina conglomerates,have been related to a strong decrease of fluvial dis-charge (Della Rocca et al., 1987) that occurred duringthe late Würm II or OIS 3 (Mazzanti, 2000).

Isola di Coltano sands - Vicarello sands and silts.These two units, interpreted as aeolian and fluvialdeposits, respectively (Fancelli et al., 1986; Mazzanti,2000), crop out locally in the present coastal plain. Theoccurrence in these sediments of musterian artifacts(Menichelli, 1984; Grifoni Cremonesi et al., 1995), indi-cating an age older than 40.000y. B.P., allows their attri-bution to the late Pleistocene (Marroni et al., 1990).Recently, these units have been correlated to the WürmII - Würm I transition or OIS 3 (Federici & Mazzanti,1995; Mazzanti, 2000).

Alluvial plain silts. This unit represents a significantportion of the present costal plain, with an average thick-ness of 30 m (Della Rocca et al., 1987). On the basis ofpollen analyses, performed on continuous cores recov-ered near the city of Leghorn (Galletti Fancelli, 1978),these deposits have been attributed to the Holocene,

mostly between the Sub-Atlantic and the Boreal phase.This chronologic attribution matches a radiocarbon ageof 6659±153 y B.P., obtained in the same area, at 22 mdepth (Ferrara et al., 1959).

North of Arno coastal plain, in the adjacent Versiliacoastal plain (where the Versilian stage has been estab-lished - Blanc, 1942), despite the remarkable amount ofstratigraphic studies available (Blanc, 1934; Marchetti &Tongiorgi, 1936; Blanc et al. 1953; Broker et al., 1956,Tongiorgi, 1956; Ferrara et al., 1959; 1961; Alessio etal., 1964; Pandolfi, 1975; Valli, 1976; 1980; Federici,1987; 1993; Federici & Mazzanti, 1995), detailed infor-mation about subsurface stratigraphy is scarce, with veryfew exceptions. One of these derives from core ENEA,90 m long, recovered at Massaciuccoli lake (Antonioli etal., 1999; Nisi et al., 2003) (Figs. 1 and 2). Stratigraphicanalysis of this core revealed two transgressive marinesurfaces, at 34 m and 70 m depth respectively. The uppertransgressive surface, dated to 10,4 ka B.P. (OIS 1), isattributable to the Holocene; on the basis of two230Th/234U dates, providing an age between 129.5 and132.8 ky B.P., the lower transgressive surface has beenattributed to OIS 5e (Tyrrhenian). This implies, for thecontinental deposits between -34 and -70 m, an ageassignment to OIS 4 to 2.

AGUZZI et al.2 Geologica Romana 38 (2005), 1-10

Fig. 1 - Geological sketch map of the study area, with indication of the section trace of Figure 4.

A time-equivalent stratigraphic succession crops outalong the Leghorn marine terrace (Bacci et al., 1939;Barsotti et al., 1974; Mazzanti, 1983; Federici &Mazzanti, 1988; Nisi et al., 2003), the inner margin ofwhich is located 15 m above the present-day sea level.This terrace was formed during the Tyrrhenian (OIS 5e)sea-level highstand (Ferranti et al., 2004), as confirmedby the presence of “Senegalese” fauna, with Strombusbubonius, in the basal calcarenite layers (panchina).Recently, a detailed study of shallow continuously-coredboreholes, drilled on the Leghorn terrace (Dall’Antonia etal., 2004), has shown that Tyrrhenian deposits are under-lain by a marine succession of Santernian-Emilian age.

The major scope of this paper is to provide for the firsttime a detailed picture of late Quaternary subsurfacestratigraphy in the lower Arno Plain, through integrationof stratigraphic data from about 300 wells with a set ofvery high-resolution stratigraphic data deriving fromtwo continuously-cored boreholes (M1 and S2 in Fig.1), ranging in depth between 40 and 106 m, that weredrilled in 2004 beneath present Arno river. Specific aimis to discuss the relationships between the new strati-graphic framework proposed in this paper and previouswork.

STRATIGRAPHY OF LATE QUATERNARYDEPOSITS IN THE LOWER ARNO PLAIN

Facies Associations

The detailed sedimentological investigation of the twocontinuously-cored boreholes (Fig. 3) reveals that LateQuaternary deposits of the lower Arno Plain consist of acyclic alternation of continental alluvial plain to shal-low-marine deposits.

Five facies associations, including fluvial-channel,crevasse splay-levee, floodplain, swamp and lakedeposits, were recognized within the alluvial plain depo-sitional system. Fluvial-channel deposits consist of grav-el- to sand-dominated sedimentary bodies, with stronglyerosional bases and characteristic elementary fining-upward (FU) successions, about 4 m thick. This faciesassociation is locally capped by organic-rich layers,marking phases of channel abandonment.

The crevasse splay/levee facies association, which iscommonly intercalated to floodplain deposits, shows therhythmical alternation, few cm thick (levee deposits), ofsilty-sand and silt. Crevasse splay deposits are character-ized by isolated, fine- to medium grained sand bodies, upto 1 m thick, that commonly display gradational basesand sharp tops. Local CU (coarsening-upward) - FUtrends may be observed.

The floodplain facies association consists predomi-nantly of monotonous alternations, up to 10 m thick, ofgrey to yellowish clay and silt. Locally, clays are stiffand display calcareous nodules, rhizhoconcretions andterrestrial small gastropods, testifying phases of subaer-ial exposure.

STRATIGRAPHIC ARCHITECTURE OF LATE QUATERNARY ... 3Geologica Romana 38 (2005), 1-10

Fig. 2 - Stratigraphy of core ENEA (modified after Antonioli et al.,1999).

AGUZZI et al.4 Geologica Romana 38 (2005), 1-10

Fig. 3 - Stratigraphic log and facies interpretation of the two cores analyzed in this paper (see Fig. 1, for location).

Swamp deposits display organic-rich layers made upof bioturbated, dark-grey to black peaty clay and silt.Freshwater gastropods, woods and leaves remains arefrequently observed. This facies association attains amaximum thickness of 3 m. In core M1, swamp depositsare intercalated to thinly laminated clays, with perfectpreservation of primary sedimentary structures, inter-preted as lake deposits.

Coastal and shallow-marine deposits include a varietyof facies associations formed in brackish to normalsalinity waters.

Brackish-water deposits consist of soft dark-grey clay,with abundant Cerastoderma and Cerithium. Sand inter-calations, a few cm- to dm-thick, rich in wood fragmentsand plant debris (flood layers) or mollusc shells (stormlayers), are commonly encountered. These layers gener-ally display sharp bases and wave-rippled tops. Thisfacies association is interpreted to have formed inlagoonal (core S2) or estuarine (core M1) environments,depending on the different paleogeography. Sand bodiesat the boundary between this facies association and over-lying beach deposits, a few dm to 3 m thick and withinternal CU trends, are interpreted to have formed asflood-tidal delta or washover deposits. CU sandy succes-sions, 2-3 m thick, at the boundary between brackish-water and freshwater deposits are interpreted as bay-head delta sands.

Among the marine facies associations, transgressivebarrier and (regressive) beach barrier deposits consist offine- to coarse-grained sand, with very abundant shellmaterial. In particular, the beach-barrier sands are about10 m thick and show well-developed CU tendencies (seecore M1 in Fig. 3). Gravels may locally occur in theupper part of this facies association.

Offshore-transition deposits are characterized by greysilty clay, with common intercalation of sharp-basedsand layers, generally a few cm thick, with rare marinemolluscs. This facies association is transitional to off-shore/prodelta deposits, which display only rare sandintercalations and abundant vegetal debris, testifying asignificant fluvial influence.

Stratigraphy of cores M1 and S2

The vertical stacking of facies within the lateQuaternary deposits of lower Arno Plain, from seawardto relatively landward locations, is best described bydetailed stratigraphic analysis of cores M1 and S2 (Fig.3).

Core M1

This core, 106 m long, has been recovered on the pres-ent Tyrrhenian coast, near Tirrenia (Fig. 1). The strati-graphic record at this location is characterized by thepresence of two intervals with marine sedimentation,between 0-51 m and 90-101 m core depths, respectively(Fig. 3). These two units, which are bounded by twoprominent transgressive surfaces (TS) are separated by

an approximately 40 m thick interval of alluvial plaindeposits.

Above about 15 m of fine-grained estuarine/lagoonalclays, the upper marine deposits show a rapid deepen-ing-upward tendency, with vertical superposition offlood-tidal delta, transgressive barrier and offshore-tran-sition deposits. The lower boundary of the transgressivebarrier facies association is marked by an erosional-based veneer of mollusc shells (ravinement surface orRS in Fig. 3). The overlying regressive trend is docu-mented by upward transition to a thick CU succession ofbeach-barrier sands.

The lower marine deposits are thinner, and dominatedby a thick beach-barrier facies association that overlie,through a ravinement surface (RS), a thin transgressivesuite of lagoonal and washover deposits.

The alluvial plain deposits located in-between are dom-inated by gravel and sand fluvial bodies, with subordinatefloodplain clays. A thick interval of fine-grained, laminat-ed deposits, attributed to a lake/swamp facies associationcan be identified between 72 and 63 m core depth.

Core S2

This core, 40 m long, has been drilled about 2 km SEof Pisa centre (Fig. 1) and 13 km NE of core M1. Unlikecore M1, and consistently with its more landward loca-tion, core S2 does not include marine deposits, and con-sists predominantly of brackish-water (lagoonal) clays,alternating with organic-rich swamp deposits (Fig. 3).Apart from recent floodplain deposits, it is remarkablethe presence of two intervals of swamp and floodplaindeposits (at depths of about 24 and 30 m), sandwichedbetween the lagoonal strata.

Given the moderate depth at which this borehole wasdrilled, core S2 is not long enough to reach the basaltransgressive surface identified at about 50 m depth incore M1.

Subsurface Architecture

Stratigraphic correlation of cores M1 and S2 (Fig. 3),along with selected stratigraphic data from boreholesbetween the Tyrrhenian coast and Pontedera, allow theconstruction of a stratigraphic cross-section depictingsubsurface stratigraphy in the lower Arno Plain (Fig. 4).

The two transgressive surfaces identified in core M1(Fig. 3) constitute two major stratigraphic markers thatcan be physically traced from seaward to landward loca-tions across the entire study area (Fig. 4). These surfaces,the orientation of which is roughly parallel to presenttopography, show a high correlation potential to the basinscale, being identifiable on the basis of the following cri-teria: i) abrupt facies change from continental (alluvialplain) to transgressive swamp (coastal plain), brackish-water (lagoonal/estuarine) or and shallow-marinedeposits; ii) local presence, above the TSs, of peats,organic-rich clays and abundant mollusc shells; iii)occurrence, just below the TSs, of laterally extensive

STRATIGRAPHIC ARCHITECTURE OF LATE QUATERNARY ... 5Geologica Romana 38 (2005), 1-10

AGUZZI et al.6 Geologica Romana 38 (2005), 1-10

Fig.

4 -

Sub

surf

ace

stra

tigra

phy

of lo

wer

Arn

o Pl

ain

from

inte

grat

ed c

ore

and

wel

l dat

a (s

ee F

ig. 1

, for

sec

tion

trac

e).

(sheet-like) fluvial-channel bodies or overconsolidatedfloodplain horizons.

Recognition of these two TSs across the entire lowerArno Plain results in identification of two transgres-sive-regressive cycles (T-R sequences in the sense ofEmbry, 1993; 1995) that thicken in seaward direction.At seaward locations, the lower parts of these T-Rsequences consist of coastal deposits. Maximum shore-line migration related to these two major transgressivepulsations is recorded at least 6 km inland of the pres-ent shoreline (see Cotoni well in Fig. 4), with scattereddata (see well 6020 in Fig. 1) indicating an even greater(10 km) shoreline migration. At more landward loca-tions, the basal nearshore deposits are laterally replacedby clay-dominated successions formed in brackishwater environments. These deposits die away upstreamover about 15 km, being replaced by an alluvial succes-sion dominated by fine-grained alluvial deposits.

The coarse-grained fluvial deposits recognized in thelower parts of the T-R sequences are embedded withinorganic-rich and brackish-water deposits, suggestingtheir possible interpretation as fluvial-mouth (bay-headdelta) deposits within a wave dominated estuarine envi-ronment (Amorosi & Milli, 2001). The local return tofreshwater (coastal plain) conditions recorded at top ofthese coarse-grained bodies is probably related to aminor regressive pulsation within the overall transgres-sive trend. The upper, regressive, parts of the T-Rsequences are characterized by an increasing proportionof alluvial deposits, with laterally-extensive fluvial-channel sedimentary bodies capping the sequences.

DISCUSSION

The stratigraphic framework reconstructed in thesubsurface of lower Arno Plain shows strong similari-ties in terms of facies architecture with several worksfrom coeval Quaternary successions of theMediterranean area (see Amorosi & Milli, 2001, andreferences therein). Given the obvious physical expres-sion of the TSs in the study area, similarly to whatrecently reported by Amorosi & Colalongo (2005) fromthe late Quaternary deposits of the Po Basin, we sug-gest here a possible subdivision of the stratigraphicsuccession of the Arno coastal plain into two transgres-sive-regressive (T-R) sequences, instead of the deposi-tional sequences of the classical EXXON models(Posamentier & Vail, 1988; Posamentier & Allen,1999).

On the basis of their stratigraphic position, we areinclined to assign the upper T-R sequence to theHolocene (Oxygen Isotope Stage 1) and the lowerboundary of the underlying T-R sequence to OIS 5e.Unpublished pollen data from core M1 (M. RicciLucchi, pers. comm., 2004) document that both TSs aredeveloped in coincidence of abrupt vertical changes inthe type of vegetation, suggesting transition from gla-cial to interglacial conditions, and thus confirming the

relationships between Quaternary T-R sequences andinterglacial-glacial cycles in the order of magnitude of100 ky (Amorosi et al., 1999; 2004). Attribution of thelower TS to the Tyrrhenian (5e) transgression is fullyconsistent with data from the Versilian Plain (Antonioliet al., 1999) indicating, on the basis of Th/U dating, thepresence of 5e deposits at 70 m depth (Fig. 2). As aconsequence, the alluvial plain deposits comprisedbetween the two intervals with marine deposits shouldbe attributed to the last glacial period (OIS 4-2).

Concerning the uppermost T-R sequence, the veryhigh thickness of Holocene sediments observedbeneath the present Arno coastal plain appears to berelated to a strongly erosional phase that preceded theonset of transgressive sedimentation in the study area.Similarly to what documented on the Tyrrhenian mar-gin for the Tevere delta (Bellotti et al., 1995; Milli,1997), where the last post-glacial depositionalsequence attains a maximum thickness of 80 m, the for-mation of an incised valley in response to sea-level fallcould account for the anomalous high thickness ofbrackish-water deposits in the Arno River area. Theseshould be interpreted as transgressive sedimentsformed in a wave-dominated estuary system during theearly stages of sea-level rise (Dalrymple et al., 1992;Nichol et al., 1994; Amorosi & Milli, 2001). Althoughthe TS is likely to merge locally with the sequenceboundary (SB), it appears as a more readily identifiablesurface at the basin scale, especially where fluvialdeposits belonging to the lowstand systems tract, andflooring the incised valley, are amalgamated with theunderlying (falling-stage or even highstand) fluvialdeposits, thus hampering a precise positioning of SB.

If compared with previous work, our data contrastmarkedly with published stratigraphic interpretations.For instance, several doubts exist about the supposedLower Middle Pleistocene chronological attribution ofthe “shallow-marine clays and sands” (Argille e sabbiedi mare sottile) observed at Bigattiera and Saint Gobainboreholes, between 100 and 86 m core depth(Romagnoli, 1957; Sartori, 1978; Fancelli et al., 1986;Della Rocca et al., 1987). The new data from core M1shown in this paper confirm the presence of shallow-marine deposits at 90-100 m depth (Fig. 3), but ourstratigraphic framework (Fig. 4) strongly suggests anage assignment of this interval to the marine ingressionthat occurred during the Last Interglacial (OIS 5e), i.e.the late Pleistocene.

Discrepancies between our work and previously pub-lished papers are even greater when dealing with strati-graphic interpretation of the Arno and Serchio daBientina conglomerates (Trevisan & Tongiorgi, 1953;Segre, 1955; Baldacci et al., 1995; Della Rocca et al.,1987), a supposed hydrogeological and stratigraphicmarker horizon extending from Pontedera to the coastalarea (Fancelli et al., 1986), and ranging in depthbetween 15 and 145 m. On the basis of Fancelli et al.(1986) interpretations, this gravel body seems to corre-spond in core M1 with the laterally extensive fluvial-

STRATIGRAPHIC ARCHITECTURE OF LATE QUATERNARY ... 7Geologica Romana 38 (2005), 1-10

channel body encountered 50-60 m below sea level(Fig. 4). If we consider, however, the depth at which thesame sedimentary body should be encountered at morelandward locations according to the map of Fancelli etal. (1986), i.e. at about 90 m depth at Bigattiera and 145m depth at Cotoni, and compare these data with the cor-relation panel of Figure 4, it is readily apparent thatprevious authors have conducted an erroneous strati-graphic correlation of sedimentary bodies located, infact, at significantly different stratigraphic levels. Inprevious studies (Federici & Mazzanti 1995; Mazzanti,2000), the Arno and Serchio da Bientina conglomerateshave been assigned to OIS 4. We have documented thatthis marker bed is inexistent; by contrast, we retainhighly plausible the attribution of the laterally exten-sive fluvial body below the Holocene transgressive sur-face to the last glacial maximum (OIS 2).

Because of confusing stratigraphic position of theArno and Serchio da Bientina conglomerates, the attri-bution of several related lithostratigraphic unitsbecomes uncertain. For instance, the Fluvial andswamp silts (Limi fluvio-palustri di sottosuolo) maycorrespond to the Holocene in the case of core M1 or,alternatively, to older stratigraphic levels (see, forexample, Bigattiera borehole), while the lithologicequivalents of the Isola di Coltano sands - Vicarellosands and silts (Sabbie eoliche dell’Isola di Coltanoand Sabbie e limi di Vicarello) have not been detectedin core M1. Finally, the Alluvial plain silts (Limi fluvio-palustri di superficie) described in Galletti Fancelli etal. (1978) can be related to the late Holocene depositsidentified in core M1, similarly to Unit 7 ofDall’Antonia et al. (2004).

CONCLUSIONS

The detailed study of the uppermost Late Quaternarydeposits of lower Arno Plain shows that a modern sedi-mentological and stratigraphic approach to the analysisof poor-quality borehole data, integrated with new high-resolution core data, may serve efficiently to the con-struction of a reliable stratigraphic framework to thebasin scale.

Stratigraphic architecture of lower Arno Plain consistsof two transgressive-regressive (T-R) sequences that areattributed to the last two interglacial-glacial cycles.Lower parts of these T-R sequences are related to themajor transgressive pulsations that took place at theonset of OIS 1 and 5e, respectively.

The transgressive surfaces are the most readily identi-fiable surfaces for sequence-stratigraphic interpretation.These marker horizons can: i) mark abrupt facieschanges from continental to coastal deposits, ii) be over-lain by transgressive, organic-rich deposits, or iii) over-lie laterally extensive fluvial-channel bodies or overcon-solidated floodplain clays, formed mostly at lowstand/falling stage conditions.

The new stratigraphic framework shown in this paperis in contrast with most of previous stratigraphic andchronologic attributions. Particularly, the remarkabledifferences in terms of stratigraphic correlations andgeometry of sedimentary bodies with respect to previouswork should be taken into account when attempting acorrect estimate of potential water resources.

ACKNOWLEDGEMENTS - We are indebted to Dr. Testa(Provincia di Pisa) for providing access to core S2. Manuscriptbenefited from comments of reviewers P. Bellotti and S. Milli.

AGUZZI et al.8 Geologica Romana 38 (2005), 1-10

Alessio M., Bella F., Cortesi C. (1964) - University of Romecarbon 14 dates II. Radiocarbon, 6, 77-90.

Amorosi A., Colalongo M.L., Fusco F., Pasini G., Fiorini F.(1999) - Glacio-eustatic Control of Continental-ShallowMarine Cyclicity from Late Quaternary Deposits of theSoutheastern Po Plain, Northern Italy. QuaternaryResearch, 52 (1), 1-13.

Amorosi A., Milli S. (2001) - Late Quaternary depositionalarchitecture of Po and Tevere river deltas (Italy) and world-wide comparison with coeval deltaic successions. Sedi-mentary Geology, 144, 357-375.

Amorosi A., Colalongo M.L., Fiorini F., Fusco F., Pasini G.,Vaiani S.C., Sarti G. (2004) - Palaeogeographic andpalaeo-climatic evolution of the Po Plain from 150-ky corerecords. Global and Planetary Change, 40, 55-78.

Amorosi A., Colalongo M.L., (2005) - The linkage betweenalluvial and coeval marginal marine successions: evidencefrom the Late Quaternary record of the Po River Plain,Italy. In: M. Blum & S. Marriott (Eds), Fluvial Sedimen-tology VII, Spec. Publ. Int. Ass. Sediment., 35, 257-275.

Antonioli F., Girotti O., Impronta S., Nisi M.F., Puglisi C. &Verrubbi V. (1999) - Nuovi dati sulla trasgressione marina

olocenica e sulla subsudenza della Pianura Versiliese attra-verso in sondaggio di 90 metri. Atti del Convegno “LePianure. Conoscenza e salvaguardia”, Ferrara, 214-218.

Argnani A., Bernini M., Di Dio G.M., Papani G., Rogledi S.(1997) - Stratigraphic record of crustal-scale tectonics inthe Quaternary of the northern Apennines. Il Quaternario,10 (2), 596-602.

Bacci A., Malatesta A., Tongiorgi E. (1939) - Di una formazio-ne glaciale rissiana riscontrata a Livorno nei sedimentidella fase costruttiva del ciclo tirreniano. Atti Soc. Sc. Nat.,Proc. Verb., 48, 74-85.

Baldacci F. (1999) - Struttura e piezometria del 1° acquiferoartesiano in ghiaie della Pianura Pisana. Atti Soc. Tosc. Sci.Nat. Mem., 106 (A), 91-101.

Baldacci F., Bellini L., Raggi G. (1995) - Le risorse idriche sot-terranee della Pianura di Pisa. Atti Soc. Tosc. Sci. Nat.Mem., 101 (A), 241-322.

Barsotti G., Federici P.R., Giannelli L., Mazzanti R.,Salvatorini G. (1974) - Studio del Quaternario livornese,con particolare riferimento alla stratigrafia ed alle faunedelle formazioni del Bacino di carenaggio della Torre delFanale. Mem. Soc. Geol. It., 13, 425-495.

REFERENCES

Bellotti P., Milli S., Tortora P., Valeri P. (1995) - Physical stra-tigraphy and sedimentology of the Late Pleistocene-Holocene Tiber Delta depositional sequence. Sedimento-logy, 42, 617-634.

Blanc A.C. (1934) - Formazioni Pleistoceniche nel sottosuolodella Versilia. Atti soc. Tosc. Sc. Na. Proc. Verb., 43, 129-143.

Blanc A.C. (1942) - Variazioni climatiche ed oscillazioni dellalinea di riva nel Mediterraneo Centrale durante l’era glacia-le. Sond. Geologie d. Meer Binnenengenwasser, 65, 50-90.

Blanc A.C., Settepassi F., Tongiorgi E. (1953) - Excursion au lacde Massaciuccoli. IV Congr. Int. Inqua, Roma-Pisa, 1-29.

Broecker W.S., Kulp J.L., Tucek C.S. (1956) - Lamont naturalradiocarbon measurements III. Science, 124, 154-165.

Dall’Antonia B., Ciampalini A., Michelacci L., Zanchetta G.,Bossio A., Bonadonna F.P. (2004) - New insights on theQuaternari stratigraphy of the Livorno area as deduced byborehole investigations. Boll. Soc. Paleont. It., 43 (1-2),141-157.

Dalrymple R.W., Zaitlin B.A., Boyd R. (1992) - Estuarinefacies models: conceptual basis and stratigraphic implica-tions. J. Sediment. Petrol., 62, 1130-1146.

Della Rocca R., Mazzanti R., Pranzini E. (1987) - Studio geo-morfologico della Pianura di Pisa (Toscana). Geogr. Fis.Dinam. Quat., 10, 56-84.

Embry A.F. (1993) - Transgressive-regressive (T-R) sequenceanalysis of the Jurassic succession of the Sverdrup Basin,Canadian Arctic Arcipelago. Ca. J. Earth. Sci., 30, 301-320.

Embry A.F. (1995) - Sequence boundaries and sequence hierar-chies: problems and proposals. In: Sequence stratigraphyon the Northwest European Margin. In Steel R.J., Felt V.L.,Johannesses E.P. and Mathieu C. (Eds), Spec. Publ.Norwegian Petrol. Soc., 5, 1-11.

Fancelli R., Grifoni R., Mazzanti R., Menchelli S., Nencini C.,Pasquinucci M., Tozzi C. (1986) - Evoluzione dellaPianura di Pisa. In Mazzanti R., Grifoni Cremonesi R.,Pasquinucci M., Pult Quaglia A.M. (Eds), Terre e Paduli.Reperti, documenti, immagini per la storia di Coltano.Bandecchi e Vivaldi, Pontedera (Pi), 23-29.

Federici P.R. (1987) - Stato attuale delle conoscenze geomor-fologiche e geologiche del Bacino di Massaciuccoli inVersilia (Toscana) III. Consorzio Idraulico CanaliNavigabili Burlamacca, Malfante, Venti e Quindici,Pacini, 27-52.

Federici P.R. (1993) - The Versilian trangression of the Versiliaarea (Tuscany, Italy) in the light of drillings and radiome-tric data. Mem. Soc. Geol. It., 49, 217-225.

Federici P.R., Mazzanti R. (1988) - L’evoluzione della paleo-geografia e della rete idrografica del Valdarno inferiore.Boll. Soc. Geogr. It., 11 (5), 573-615.

Federici P.R., Mazzanti R. (1995) - Note sulle pianure costieredella Toscana. Mem. Soc. Geol. It., 53, 165-270.

Ferranti L., Amorosi A., Antonioli F., Dai Prà G., Lezziero A.,Mastronuzzi G., Mauz B., Monaco C., Orrù P., PappalardoM., Radtke U., Renda P., Romano P., Sansò P. (2004) -Altitude and spatial distribution of the MIS 5.5 highstandmarker in Italy: relation with active tectonic processes.32nd International Geological Congress, Florence, August20-28 2004.

Ferrara G., Reinharz M., Tongiorgi E. (1956) - Carbon-14dating in Pisa. I. Am. Journ. Sci. Radioc. Supp., 1, 103-110.

Ferrara G., Fornaca Rinaldi G., Tongiorgi E. (1961) - Carbon-14 dating in Pisa II. Radiocarbon, 3, 99-104.

Galletti Fancelli M.L. (1978) - Ricerche sulla subsidenza dellapianura pisana. Analisi polliniche di sedimenti quaternaridella pianura costiera tra Pisa e Livorno. Boll. Soc. Geol.It., 98, 197-245.

Ghelardoni R., Giannini E., Nardi R. (1968) - Ricostruzionepaleogeografica dei bacini neogenici e quaternari dellabassa valle dell’Arno sulla base dei sondaggi e rilievisismici. Mem. Soc. Geol. It., 7, 91-106.

Gioli G. (1894) - Il sottosuolo della pianura di Pisa. Boll. Soc.Geol. It., 13, 210-233.

Grifoni Cremonesi R., Tozzi C. (1995) - Gli insediamenti dalPaleolitico all’età del Bronzo. In: Mazzanti R. (Ed), LaPianura di Pisa ed i rilievi contermini, Provincia di Pisa,153-182.

Malinverno A., Ryan W.B.F. (1986) - Extension in theTyrrhenian sea and shortening in the Apennines as a resultof arc migration driven by sinking of the lithosphere.Tectonics, 5, 227-245.

Marchetti M., Tongiorgi E. (1936) - Ricerche sulla vegetazio-ne dell’etruria Marittima, VII. Una torba glaciale del LagoMassaciuccoli (Versilia). Nuovo Giornale botanico It., 43.

Mariani M., Prato R. (1988) - I bacini Neogenici costieri delmargine tirrenico: approccio sismico-stratigrafico. Mem.Soc. Geol. It., 41, 519-531.

Marroni M., Mazzanti R., Mencini C. (1990) - Geologia e mor-fologia delle colline Pisane. Quad. Mus. Stor. Nat. diLivorno, 11 (1), 1-40.

Martini I.P., Sagri M. (1993) - Tectono-sedimentary characteri-stic of late Miocene-Quaternary extensional basin ofNorthern Appennines. Earth Science Reviews, 34, 197-233.

Mazzanti R. (1983) - Il punto sul quaternario della fasciacostiera e dell’Arcipelago della Toscana. Boll. Soc. Geol.It., 102, 419-556.

Mazzanti R. (1994) - La Pianura di Pisa ed i rilievi contermini.In: Mazzanti R. (Eds), Provincia di Pisa.

Mazzanti R. (2000) - Geomorfologia del bacino Versiliese-Pisano con particolare riferimento alla “Gronda dei Lupi”,scarpata fossile che separa le Colline Livornesi, con i loroterrazzi eustatici, dalla pianura alluvionale pisana. Atti Soc.Tosc. Sci. Nat., Mem., A, 165-189.

Meletti C., Patacca E., Scandone P. (1995) - Il sistema com-pressione-distensione in Appennino. In. Bonari G, De VitoB., Gasparini P., Vallario A. (Eds): Cinquanta anni di atti-vità didattica del Prof. Felice Ippolito, Liguori, Napoli,361-370.

Menchelli S. (1984). Contributo allo studio del territorio pisa-no: Coltano e l’ex Padule di Stagno. Studi classici orienta-li, 32, 255-270.

Milli S. (1997) - Depositional setting and high-frequencysequence stratigraphy of the Middle-Upper Pleistocene toHolocene deposits of the Roman Basin. Geol. Rom., 33,99-136.

Nagi A., Pascucci V. (2002) - Alternating extensional phases inpost collisional basin: the Neogene Viareggio basin(Tuscany, Italy). GIS 2002, IX riunione annuale del

STRATIGRAPHIC ARCHITECTURE OF LATE QUATERNARY ... 9Geologica Romana 38 (2005), 1-10

Gruppo Informale di Sedimentologia, Pescara 21-22Ottobre, 67-68.

Nichol S.L., Boyd R., Penland S. (1994) - Stratigraphicresponse of wave-dominated estuaries to different relativesea-level and sediment supply histories: Quaternary casestudies from Nova Scotia, Louisiana and Eastern Australia.In: Dalrymple, W., Boyd, R., Zaitlin, B.A. (Eds), Incised-Valley Systems: Origin and Sedimentary Sequences. Soc.Econ. Paleontol. Mineral. Spec. Publ., 51, 265-283.

Nisi M., Antonioli F., Dai Pra G., Leoni G., Silenzi S. (2003) -Coastal deformation between the Versilia and theGarigliano plains (Italy) since the last interglacial stage.Journal Of Quaternary Science, 18 (8), 709-721.

Pandolfi D. (1975) - La sabbia silicea della bassa Versilia ed isuoi impieghi. Ed. S.E.A., Carrara.

Pascucci V., Fontanesi G., Merlini S., Martini I.P. (2001) -Neogene Tuscany shelf-western Tuscany exetension of theearly post-compressional deposits (Tyrrhenian Sea -Northern Appennines, Italy). Ofioliti, 26/2a, 187-196.

Patacca E., Sartori R., Scandone P. (1990) - Tyrrhenian basinand Apenninic arcs: kinematic relations since lateTortonian times. Mem. Soc. geol. Ital., 45, 425-451.

Posamentier H.R., Vail P.R. (1988) - Eustatic controls on clas-tic deposition II - Sequence and systems tract models. In:WILGUS C.K., Hastings B.S., C.G St.C. Kendall,Posamentier H.V., Ross C.A., Van Wagoner (Eds), Sealevel changes: An Integreted Approach, Soc. Econ.Paleont. Miner., Spec. Publ., 42, 125-154.

Posamentier H.W, Allen G.P. (1999) - Siliciclastic SequenceStratigraphy - Concepts and Applications. SEPM Conceptsin Sedimentology and Paleontology, 7.

Romagnoli L. (1957) - Sondaggi a 200 m di profondità nelQuaternario recente presso Pisa. Studio delle facies attra-versate e considerazioni sulla sedimentazione costiera acarattere ciclico, Boll. Soc. Geol. Ital., 76, 21-35.

Sartori F. (1978) - Studi sedimentologici e mineralogici dellealluvioni recenti della pianura pisana. I sedimenti del son-daggio della Bigattiera, presso S. Piero a Grado (Pisa ). AttiSoc. Tosc. Sci. Nat., Mem., 85 (A), 61-93.

Sartori R. (1989) - Evoluzione neogenico-recente del bacinotirrenico e i suoi rapporti con la geologia delle aree circo-stanti. G. Geol., 51 (3), 1-30.

Segre A.G. (1955) - Nota sull’idrografia continentale e marina.Note illustrative del C.G.I., scala 1:100000, Foglio 111,Livorno, Serv. Geol. It., Roma, 20-26.

Tongiorgi E. (1956) - Le variazioni climatiche della serieFiandriana nella pianura della bassa Versilia presso il lagodi Massaciuccoli. N. Gior. Bot. It., 43, 762-764.

Trevisan L., Tongiorgi E. (1953) - Le acque del sottosuolodella pianura pisana. La Provicia Pisana, 9-10.

Valli S. (1976) - Il giacimento malalcologico di MigliarinoPisano. Nota preliminare. Boll. Inf., Gruppo A.C. Blanc,Viareggio, 14, 12-15.

Valli S. (1980) - Indagini sulle zone umide della Toscana. VIII.Il giacimento malacologico del padule di Massaciuccoli.In: Il bacino di Massaciuccoli, 1, Pacini, Pisa.

AGUZZI et al.10 Geologica Romana 38 (2005), 1-10

Accettato per la stampa: Giugno 2005