TRAVERTINE VERSUS CALCAREOUS TUFA: 
DISTINCTIVE PETROLOGIC FEATURES AND STABLE ISOTOPES SIGNATURES 

Anna Gandin & Enrico Capezzuoli  
Dip. Scienze della Terra, Università di Siena, Via Laterina 8, 53100 Siena

e.mail: gandin@unisi.it 

Abstract:  A. Gandin & E. Capezzuoli, Travertine versus Calcareous tufa: distinctive petrologic features and stable isotopes signatures.
(IT ISSN 0394-3356, 2007). 
Terrestrial limestones, mainly deposited as calcite crusts by carbonate-rich waters flowing in subaerial settings, originate from warm-
to-hot waters of hydrothermal provenance (travertines) or from cool waters of karstic derivation (calcareous tufa). The two groups of
concretionary carbonates are actively forming in different geomorphologic settings such as cool-water springs and fluvial valleys, or in
the surroundings of the emergence of thermal springs. Fossil remains of these rocks are frequently found in calcareous areas as well
as in areas where carbonate rocks are not exposed. However the recognition on the field of their genetic derivation when connections
with the feeding source are no more evident, is often uncertain since the definition of the specific litofacies are not yet completely elu-
cidated. 
The detailed analysis of the lithofacies of calcareous tufa and travertines as well as the critical elaboration of existing geochemical
data, shows that the petrologic features and stable isotopic signatures reflect the contrasting environmental conditions of deposition
deriving from physico-chemical properties of the feeding waters that, although mostly of meteoric provenance, experienced different
circulation/recharge history. 
Travertines are well bedded, often finely laminated compact limestones, composed in the proximal part of the thermal system by
peculiar crystalline crusts and in the distal part by bacterial/cyanobacterial laminites often associated with thin crystalline crusts, len-
ses of calcified-bubbles and paper-thin rafts.
In this system the carbonate deposition mainly derives from intense outgassing of the emerging supersaturated waters, and evapora-
tion, concomitant with the rapid drop in temperature along the drainage network. 
Travertine mineral content originates in deep geothermal/hydrothermal conditions where hot waters charged with HCO3

- of meteoric
and hypogean derivation, are able to dissolve high quantities of carbonate and/or evaporitic bedrock. The circulation of hot waters,
allowed by open fractures/faults is ultimately controlled by extensional tectonics.
Calcareous tufa are poorly bedded, porous/chalky deposits containing frequent remains of macrophytes and invertebrates. They are
made up of dominantly microcrystalline calcite of abiotic and biotic precipitation, forming phytohermal, stromatolitic or phytoclastic
facies. It is commonly found in fluvial/palustrine depositional systems fed by carbonate-rich waters mostly deriving from karstic
springs. The carbonate deposition deriving from mainly mechanical (vaporization/evaporation) and less significant biologic removal of
CO2 from flowing or standing waters, results to be controlled by the availability of meteoric water and ultimately by local and/or global
climatic conditions.
The comparison of petrofacies and the critical elaboration of the related stable isotopic signatures of deposits still connected with the
parent water and source systems, provide criteria for the univocal lithologic identification of their fossil counterparts so that the mainly
climate-controlled Calcareous Tufa and the mainly tectonics-controlled Travertines can be easily detected even on the field. 

Riassunto: A. Gandin & E. Capezzuoli, Travertini e Calcareous tufa: caratteristiche petrologiche e isotopiche. (IT ISSN 0394-3356,
2007). 
Tra i carbonati continentali sono compresi i sedimenti prevalentemente formati da croste calcaree derivati da acque dolci scorrenti ric-
che in carbonato di calcio. In base alle caratteristiche fisiche di queste acque, è possibile distinguere i depositi originati da acque
“calde” di provenienza idrotermale (travertini) da quelli precipitati da acque “fredde” di derivazione carsica (calcareous tufa). Questi due
gruppi di calcari concrezionari sono caratteristici di sistemi deposizionali e geomorfologici molto differenti: sorgenti termali i primi,
ambienti fluvio-palustri i secondi.
Affioramenti fossili di questi depositi si trovano comunemente, ma il riconoscimento sul terreno della loro derivazione genetica è spes-
so incerta a causa dell'assenza di una precisa definizione specifica delle relative litofacies.
L'analisi dettagliata delle litofacies dei travertini e dei calcareous tufa e la contemporanea elaborazione critica dei dati geochimici rica-
vati dalla letteratura mostra che le loro caratteristiche petrologiche e isotopiche riflettono le caratteristiche fisico-chimiche delle acque
di origine le quali, anche se hanno la stessa derivazione meteorica, testimoniano di una differente ricarica e circolazione idrogeologica.
I travertini sono carbonati compatti, ben stratificati e in genere fittamente laminati. Essi si originano esclusivamente nelle vicinanze di
sistemi idrotermali. Nella zone prossimali la fuoriuscita e lo scorrimento di acque calde sovrassature in carbonato di calcio determina la
formazione di peculiari croste cristalline, mentre nelle porzioni più distali divengono predominanti le lamine batteriali/cianobatteriali
spesso associate con sottili lamine cristalline, lenti di bolle gassose incrostate e impronte di vegetali. Gli alti tassi di accrescimento dei
travertini sono condizionati dal veloce degassamento delle acque supersature e dall'evaporazione.
Il contenuto minerale delle acque riflette la natura delle condizioni idrotermali/geotermali nelle quali acquisiscono calore durante il loro
percorso profondo. La temperatura di queste acque, ricche di HCO3

- di derivazione meteorica o anche magmatica, infatti, permette la
dissoluzione di grandi quantità di carbonati o solfati contenuti nelle rocce del substrato. La loro circolazione, intimamente connessa alla
presenza di faglie/fratture beanti, è strettamente controllata dalla tettonica principalmente di tipo estensionale.
I calcareous tufa sono depositi generalmente porosi e scarsamente stratificati, contenenti abbondanti tracce di macrofite e invertebrati.
Essi sono composti principalmente da calcite microcristallina di precipitazione abiotica e biotica che forma facies fitoermali, stromatoli-
tica o fitoclastica caratteristiche di ambienti deposizionali fluvio-palustri con acque carbonatate derivanti da sistemi carsici. La deposi-
zione, in genere lenta e con bassi tassi di accrescimento, è principalmente controllata dalla rimozione meccanica (vaporizzazione/eva-
porazione) e biologica (fotosintetica) della CO2 da acque scorrenti o stagnanti. Tale processo risulta ovviamente condizionato dalla
disponibilità di acqua meteorica e, di conseguenza, dalle condizioni climatiche.
Il confronto delle diverse petrofacies e l'elaborazione critica dei relativi contenuti isotopici derivati da depositi ancora connessi con le
loro acque madri, fornisce un criterio per un'univoca identificazione litologica dei depositi fossili. In tal modo i calcareous tufa ed i tra-
vertini possono essere facilmente riconosciuti anche sul terreno, allo scopo di discernere quelle strette relazioni con il clima (calcareous
tufa) e con la tettonica (travertini) che li caratterizza e che li ha posti al centro della ricerca internazionale nell'ultimo decennio. 

Key words: Travertine, calcareous tufa, sedimentology, petrology, stable isotopes.

Parole chiave: Travertini, Calcareous tufa, Sedimentologia, Petrografia, Isotopi stabili.

Il Quaternario
Italian Journal of Quaternary Sciences
21(1B), 2008 - 125-136



126 A. Gandin & E. Capezzuoli

1. INTRODUCTION

Continental carbonates are vulnerable rocks that
in the geologic record rarely survive erosion and disso-
lution but are extensively recorded in the Quaternary
continental successions of areas where the exposed
and/or buried carbonate bedrock acts as calcium reser-
voir for the circulating groundwaters. However terre-
strial limestones are presently forming on the Earth sur-
face, in different geomorphologic/geodynamic settings
under a wide range of conditions and are controlled by
contrasting physico-chemical properties of the waters.
Remnants of their fossil counterparts are frequently
found in calcareous areas as well as in areas where
carbonate rocks are not exposed, and disconnected
from their primary setting. Consequently their origin and
paleoenvironmental meaning can be difficult to assess
since most of the published data do not account for the
lithologic and petrographic features of the different
types of terrestrial carbonates.

Continental limestones deposited as primary cal-
cite crusts by flowing carbonate-rich waters are also
known as flowstones. Lacustrine alike marine pelagic
carbonates, settles in standing body of water below the
high-energy zone (wave base). They are mostly repre-
sented by lime-mudstone composed of microcrystalline
calcite (micrite).

Flowstones include speleothems, deposited in the
subsurface environment of the karst system, and spring
related carbonates deposited in open-air conditions but
in different geomorphologic settings and contrasting
physico-chemical  properties of the waters.
Groundwaters mostly of meteoric origin acquire, during
more or less deep geothermal circulation pathway, dif-
ferent temperatures and saline concentrations rising at
the spring as supersaturared/saturated carbonate
waters, warmer (thermal) or cooler (karstic) than the
ambient temperature.

In the current nomenclature the appellation of
thermogene and meteogene travertines proposed by
PENTECOST & VILES (1994) that however does not take in
account the genetic sedimentary and environmental
processes, is sometimes still used (MI N I S S A L E et al. ,
2002; PENTECOST, 1995; 2005 and reference herein). The
more realistic terminology of travertines, calcareous
tufa and speleothems, proposed by RI D I N G (1991) and
FORD & PEDLEY (1996), is based on the litho-genetic fea-
tures of terrestrial flowstone carbonates and takes also
in account the historical term of travertine.

Travertine is the long time appellation of a com-
pact laminated calcareous lithology quarried since
Etruscan times in Etruria (present-day Tuscany and
northern Latium; GA N D I N et al., 2006) and in Roman
times near the town of Tibur (present name is Tivoli)
where it is formed ("lapis tiburtinus") by hot waters
rising from tectonically controlled presently active
hydrothermal springs (FACCENNA et al., 1994), still called
Acquae albulae (Latin for "whitish waters"). Thus the
Tivoli area must be considered the geological type-
locality of the thermal-related terrestrial limestone, the
Travertine.

Calcareous tufa is the recent denomination of
highly porous massive limestone deposited from cool
or ambient temperature waters of karstic and/or meteo-
ric derivation, in climate controlled alluvial/palustrine
systems (PEDLEY, 1990; FORD & PEDLEY, 1996).

Speleothems, mainly stalactites, stalagmites and
flowstones, are finely laminated macrocrystalline hypo-
gean deposits bui lt by successive rows of
acicular/radiaxial, often ferroan calcite (FR I S I A, 2003). It
slowly precipitates from water drops in the dark subsur-
face, vadose conditions of the cave systems.

In many of the thermal or cool water spring-rela-
ted subaerial sites where active deposition occur, older,
often terraced deposits, even if affected by post-depo-
sitional processes (diagenetic cementation and/or kar-
stic epigenetic dissolution and erosion), attest to the
continuity of the sedimentation and show evidence of
the different depositional pattern of the respective car-
bonate bodies. However since the meaning of the spe-
cific petrologic features of these sediments are not well
known, they are often mixed up under the all-compri-
sing term of travertine (JULIÀ, 1983; TURI, 1986; CILLA et
a l. 1994; CH A F E T Z & LA W R E N C E, 1994; PE N T E C O S T, 2005;
DU B A R, 2006 and references therein), disregarding
detailed lithologic descriptions already published (FORD

& PE D L E Y, 1996; GU O & RI D I N G, 1998; 1999) and the
potential information that their dissimilar depositional
settings imply (CAPEZZUOLI & GANDIN, 2004).

The purpose of this article is to investigate on the
relationships between the specific petrologic features
and fabrics of "living" travertines and calcareous tufa
and their distinctive physico-chemical properties and
isotopic signature. The results of the critical elaboration
of new and existing data will provide petrologic criteria
supported by isotopic data, for the genetic, climatic or
tectonic/geologic identification of “old” terrestrial car-
bonate deposits no more connected with their primary
source systems.

2. DEPOSITIONAL AND ISOTOPIC CHARACTERI-
STICS OF TRAVERTINES AND CALCAREOUS TUFA

Subaerial flowstones originate in depositional
systems characterized by contrasting environmental
and physico-chemical properties and different sources
of the mineral content of the waters. The specific petro-
logic features of spring-related calcareous deposits and
the rate of crystal growth, results from the physico-che-
mical characteristics of precipitation processes that
ultimately are controlled by the conditions of the
flowing fluids, such as velocity of the flux, outgassing,
ionic concentration and temperature. Temperature of
spring and stream waters in turn, is controlled by the
temperature the groundwater reaches in the hypogean
circulation.

Source of the Ca-bicarbonate-rich waters are shal-
low (karstic) or deep (geothermal) subsurface circulation
networks where waters charged of dissolved CO2 of soil
and/or meteoric derivation interact with the
carbonate/evaporitic and/or magmatic bedrock and out-
flow from hydrothermal or karstic springs, as warm/hot
or cool waters. The HCO3

- and Ca+ 2 ions dissolved in
more or less concentrated solutions are of mixed prove-
nance mostly meteoric, partially recycled (dissolution of
bedrock carbonates and/or evaporites) locally magmatic.

The hydrothermal system develops in areas where
deep tensional fractures (HANCOCK et al., 1999; SHIPTON

et al., 2004; ALTUNEL, 2005; BROGI & CAPEZZUOLI, 2008) or
volcanic intrusions promote the hypogean circulation
and heating of waters of meteoric and/or juvenile deri-



vation. The mineral content of the outflowing thermal
waters (min 20°C up to 90°C, PENTECOST, 2005) origina-
tes from the dissolution of high quantities of carbonate
and/or evaporitic bedrock that often is not exposed on

127Travertine versus Calcareous tufa ...

the surface. The subaerial circulation of the warm,
sulphur/sulphate-rich thermal waters appears to be
adverse to the vegetation, giving rise to an arid/desert
white landscape (CAPEZZUOLI & GANDIN, 2005) (Fig. 1a). 

Fig. 1 -Examples of the thermal, "white desert" environment and related travertine deposits: a) shallow pools barred by crystalline rim-
stones along a low-gradient slope (Pamukkale, Turkey); b) the steep slope of a dried waterfall covered by micro terraces and
larger/deeper bowl-like basins (Terme San Giovanni, Rapolano Terme, Italy); c) well bedded, laminated body of travertine showing a
low-angle unconformity and dark intervals (black arrows) corresponding to lacustrine/pedogenetic episodes (Serre di Rapolano, Italy);
d) transversal flexure-like section of a dam rimstone composed of regularly laminated crusts of crystal fans (Bagno Vignoni, Italy).
Microfabrics of crystalline crust travertine: e) crystal fans made of finely laminated cloudy fibrous calcite (Rapolano Terme, Italy); f)
feather-like bacterial/crystal shrubs partially growing on encrusted gas bubbles (Rapolano Terme, Italy).
Esempio di ambiente termale desertico "il deserto bianco ", e dei relativi depositi travertinosi; a) Pendio poco acclive con vasche
disposte a terrazzo delimitate da bordi cristallini (Pamukkale, Turchia); b) Porzione acclive di una cascata inattiva coperta da micro- e
macroterrazzi a forma di scodella (Terme San Giovanni, Rapolano, Italia); c) Corpi di travertino laminato e ben stratificato. Sono evidenti
una discordanza a basso angolo e intervalli scuri (frecce nere) corrispondenti a episodi lacustri e/o pedogenetici (Serre di Rapolano,
Italia); d) Sezione trasversale del bordo di una vasca formato da croste incurvate di calcite cristallina a ventaglio ben stratificata (Bagno
Vignoni, Italia). Microfabric delle croste cristalline di travertino: e) Ventagli di calcite aciculare finemente laminata con concentrazioni di
impurezze (Rapolano Terme, Italia); f) cespugli batteriali/cristallini a forma di piuma in parte accresciuti su bolle di gas incrostate
(Rapolano Terme, Italia).



The karstic system, a shallow subsurface vadose
network, developed in areas where carbonate rocks are
exposed and the supply of meteoric water is rather
abundant, yields mineralised waters which outflow at the
spring with temperatures commonly cooler than the sur-
rounding ambient but more or less stable throughout the

year within the cave system (HO R V A T I N C I C et al., 2003).
The Ca-rich waters giving rise to carbonate depo-

sits, at the same time promote the establishment of a
well developed riverine/palustrine depositional system
and the growth of luxuriant vegetation (Fig. 2a, b). 

Notwithstanding the extremely different physico-

128

Fig. 2 - Examples of well vegetated fluvial/palustrine environment and related calcareous tufa deposits: a) Diborrato, dam and pool
system (Colle Val d'Elsa, Italy); b) Yenice, cascade system (Meander River valley, Turkey); c) massive, phytohermal tufa composed of
staked cushion-like elements (Diborrato, Colle Val d'Elsa, Italy); d) transversal flexure-like section of a dam rimstone composed of irre-
gularly superposed biostromal layers (Diborrato, Colle Val d'Elsa, Italy). Microfabrics of calcareous tufa: e) organic remains (white
arrows) alternated with rows of limpid crystalline calcite (“stromatolitic” facies; Colle Val d'Elsa, Italy); f) Rivularia filaments enclosed in
limpid sparite (Phytohermal facies, La Pigna falls, Monticiano, Italy).
Esempi di ambienti fluviali/palustri ben vegetati e dei relativi depositi di calcareous tufa: a) Sistema di vasche e bordi rialzati (rimstones)
presso il Diborrato (Colle Val d'Elsa, Italia); b) Sistema di cascata presso Yenice (Fiume Meandro, Turchia); c) calcareous tufa fitoermali
mal stratificati composti da elementi a cuscino sovrapposti (Diborrato, Colle Val d'Elsa, Italia); d) Sezione trasversale del bordo di una
vasca formato da croste biostromali incurvate e irregolarmente sovrapposte (Diborrato, Colle Val d'Elsa, Italia). Microfabric di calca-
reous tufa: e) alternanza di livelli scuri con residui organici (frecce bianche) e di livelli di calcite cristallina limpida (facies “stromatolitica”,
Colle Val d'Elsa, Italia); f) Filamenti di Rivularia inclusi in cristalli di calcite spatica (Facies Fitoermale, Cascata de La Pigna, Monticiano,
Italia).

A. Gandin & E. Capezzuoli



chemical properties of the waters of the two spring
systems, some of the physical processes connected
with the precipitation of calcium carbonate give rise to
similar depositional structures in the carbonate bodies
that however are characterized by completely different
fabrics and biologic involvement (Fig. 1, 2).

Precipitation of calcium carbonate mainly derives
from the removal of CO2 from carbonate-rich waters
and its amount is consistent with the concentration and
temperature of the parent water. 

Abiotic/physical precipitation is dominant under
turbulent flow regime whereas evaporation and effecti-
ve biomediation/photosynthetic action requires sluggi-
sh flow or static water (PEDLEY, 1990).

Vaporization and outgassing, largely dominant
processes connected with falls, rapids and the presen-
ce of obstructions on the stream paths, contribute to
the passive encrustation of every object vegetal, animal
or rock the flow runs into. The rapid removal of CO2
acting during the water drift or within static waters of
intervening basins, moreover, induces the precipitation
of solid encrusting calcite in a succession of arcuate
rims/barrages/terraces (r imstones) that delimit
pools/ponds of variable sizes and depths (Fig. 1a,b;
Fig. 2a,b), depending on the amount of flowing water
and the gradient of the drainage path (HA M M E R et al,
2007; PEDLEY et al., 1996; PENTECOST, 2005).

Evaporation is also a physical process induced by
higher temperatures of the water at the air/water inter-
face of shallow small or large basins. Consequent,
occasional whitenings result in abiotic microcrystalline
calcite that, together with possible biotic micrite produ-
ced by the photosynthetic activity of aquatic organi-
sms, settle as lime mud on the bacterial biofilms sup-
ports made of extracellular polymeric substances (EPS)
at the bottom of the basin. 

Growing evidence indicates that active
biologic/photosynthetic contribution to the carbonate
precipitation results to be effective even if actually
negligible, mostly in the fluvial/palustrine system where
dominant macrophytes prosper because of the cool
and humid conditions of the environment (MERZ- PREISS

& RIDING, 1999). In the hot waters of thermal springs and
in their arid surroundings, conditions of life are extreme
and the organisms involved, mostly heat-loving bacte-
ria, play a passive role of support to the precipitating
calcite.

Bacterial colonies are commonly found in both
systems; they settle in lower-energy microhabitats/
niches sheltered from the tractive flow on the bottom of
the basins, or on the sides of channels, and passively
incorporate carbonate particles in the mucilaginous bio-
film (EPS) they produce (MERZ-PREISS & RIDING, 1999). 

The sediment that settles within the floodbasins is
in part carbonate sand transported by the flow but
most of it has specific features that reflect the original
concentration of the water and the difference between
water and ambient temperatures.

In the assumption that the δ13C and δ18O values of
subaerial flowstones must reflect the different physico-
chemical properties of the parent waters, a survey has
been carried out of the published stable isotope data
on recent deposits of well known origin collected in the
most significant present day sites of formation (Fig. 3,
4) with the intent to find the possible relationships

between the overall depositional conditions of each
spring system and the resulting sedimentary and petro-
logic features. 

The geochemical ratio of the stable isotope pairs
of carbon and oxygen (1 2C, 1 3C and 1 6O, 1 8O) depends
mostly on the physico-chemical conditions of water
(temperature and saline/CO2 concentration) that pro-
mote isotopic fractionation. Ratios compared to a stan-
dard sample (PDB = a Cretaceous belemnite; SMOW =
Standard Mean Ocean Water, only for oxygen) are
expressed in the δ PDB or SMOW (‰) notation provi-
ding an expanded scale for the comparatively small dif-
ferences observed. Fractionation, resulting from the
loss for evaporation, degassing or metabolic consump-
tion of the lighter isotopes during the (bio)geochemical
cycle, induces discrete changes of C and O ratios.
Their values therefore provide information about the
physico-chemical conditions of the precipitation events
(rate and temperature) and the influence of potential
metabolic processes, hence about the sources of water
and carbon dioxide as well. It also provides information
on the temperature at which deposition occurred and
assists in radiometric dating (more references in: FOUKE

et al., 2000; ANDREWS, 2005; PENTECOST, 2005).

3. TRAVERTINE

Present day hydrothermal systems where traverti-
ne is forming (the San Giovanni Terme spring system at
Rapolano near Siena - Fig. 1b,c,d - is an excellent
example; BA R A Z Z U O L I et al., 1988), are fed by warm to
hot carbonate-rich waters, often charged with other
ionic compounds such as sulphate/sulphide, chlorine,
etc., surfacing from linear or punctiform vents.

The mineral content of the hot waters originates in
deep geothermal/hydrothermal conditions where hea-
ted waters charged with HCO3

- of meteoric and hypo-
gean/magmatic derivation, are able to dissolve high
quantities of carbonate and/or evaporitic bedrock. Their
circulation, allowed by open fractures/faults, is ultima-
tely controlled by extensional tectonics (SI B S O N, 2000;
HANCOCK et al., 1999; BROGI et al., 2005; BROGI & CAPEZ-

ZUOLI, 2008). 
In this system carbonate deposition, marked by a

high-rate production, mainly derives from intense out-
gassing of CO2 and evaporation of the emerging waters
which concurs to the rapid drop in temperature of the
supersaturated waters flowing along the drainage
network. 

The biological contribution in the thermal spring
environment is not relevant since the subaerial circula-
tion of warm/hot, unhealthy carbonate-saline waters
prevents the development of macrophytes. Only heat-
loving bacteria develop on humid surfaces or warm
water puddles and pools (CH A F E T Z & FO L K, 1984).
Moreover, precipitation of calcite is so rapid that even
bacteria and cyanobacteria have no time/possibility to
colonize the carbonate surface that remains a bare
white desert landscape (Fig. 1). 

In the desert thermal landscape the rapid removal
of CO2 results from the simultaneous processes of out-
gassing, vaporizing/cooling combined with the surface
flow characteristics that in turn are controlled by the
morphologic gradient of pre-existing or self-built slopes

129Travertine versus Calcareous tufa ...



(Fig. 1a,b). Velocity and turbulence of the flow control
the shape and distribution of the sedimentary bodies.
Smooth flows running on flat to inclined surfaces,
where obstructions are rare and commonly of small size
(Fig. 1a), gives rise to plane, regularly laminated beds,
locally showing a large scale lenticular trend (Fig. 1c).
The resulting carbonate edifices vary in shape from
suspended channels to cones and ridges made up of
coalescing smaller cones or vents. Conversely turbulent
flows give rise to waterfalls and rimstones (Fig. 1b) of
any size (large rimmed terraces to microterraces) made
of calcite beds arranged in a succession of structural
flexures (Fig. 1d) producing arcuate barrages that deli-
mit shallow floodbasins (Fig. 1a,b). 

The sedimentary architecture resulting from this
depositional system defines the carbonate lithotype
designated as travertine. It is characterized by well bed-
ded, finely laminated limestones, composed in the
proximal part of the thermal system by peculiar macro-
crystalline crusts and in the distal part by bacterial/cya-
nobacterial microcrystalline/mud-supported sediment
(GUO & RIDING, 1998; 1999; ÖZKUL et al., 2002). The spe-
cific petrologic features are represented by regularly
laminated, commonly flat bodies built up by a compact,
laminated crystalline fabric composed of feather-like
crystals (Fig. 1f) or crystal bushes grown from smooth
flows along low gradient drainage channels or of crystal
fans (Fig. 1e) deriving from turbulent flood in waterfalls.
Interbedded lenticular bodies of microcrystalline, gra-
nular or mud supported deposits correspond to the
backfill of ponds and puddles that varies in texture and
content depending on their distance from the vent,
hence on the temperature and concentration of the
water. On the standing waters of proximal basins, whi-
tenings related to evaporation hence rapid removal of
CO2, induce the precipitation of microcrystalline calcite
on bacterial biofilm supports (EPS) at the bottom of the
basin, giving rise to a characteristic spongy fabric (see
fig. 4c in GANDIN et al., 2006). 

Brittle crystalline crusts often form on the hot
water surface floating pack-like until, under the increa-
sing load of calcite and cyanobacterial growth, sink at
the bottom in stacks of slabs, giving rise to the paper-
thin raft fabric described by GU O & RI D I N G (1998). In
secluded parts of channels the combined actions of
bacterial/biological activity outgassing and evaporation
induce the formation of peculiar foam-like structures
made of gas bubbles coated by a microcrystalline cal-
cite film and sometimes encrusted also by feather-like
crystals (Fig. 1f).

In the more distal basins the lime mud-fill contains
remains of ostracods, gastropods, C h a r a and diatoms
attesting the presence of life and consequently of coo-
ler less mineralised waters. Associated with the lacu-
str ine-l ike facies, more or less developed
pedogenetic/root concretions, document episodic
desiccation and pedogenetic processes deriving from
the interruption and/or diversion of the water flux.

Geochemical analyses of presently forming tra-
vertines have been performed on samples collected
from several thermal localities as the Yellowstone Park
hydrothermal springs systems (FR I E D M A N, 1970; FO U K E

et al., 2000); in Italy Le Zitelle springs near Viterbo and
Bagni San Filippo on the Monte Amiata (Siena), related
to volcanic complexes (GONFIANTINI et al., 1968; CHAFETZ

& LA W R E N C E, 1994) and the Rapolano/Acqua Borra
(Siena) geothermal springs (GUO et al., 1996); in Spain
near Granada (JIMENEZ DE CI S N E R O S et al., 2006). The
temperature of the parent groundwaters at the emer-
gence of the studied thermal springs (Fig. 3) vary from
34°C (Spain) up to 60°C (Le Zitelle) and 73°C
(Yellowstone). 

Stable isotopic data obtained from calcite precipi-
tated from hot/warm waters in these localities, have
been plotted on a Cartesian coordinate system where it
is possible to observe that the δ1 3C versus δ1 8O PDB
values falls in the same field of distribution characteri-
zed by dominantly positive δ13C values (Fig. 3).

The δ18O (PDB) range from -4‰ to -30‰, appears
to be influenced by high temperatures and supersatura-
tion levels of the outflowing waters (FR I E D M A N, 1970;
GU O et al., 1996; FO U K E et al., 2000). The increase of
δ18O values indicates evaporation of the lighter isotope
1 6O and cooling of the waters, whereas heavier values
of δ1 3C reflect removal of the lighter isotope 1 2C, and
consequent outgassing of CO2 (GONFIANTINI et al., 1968;
USDOWSKI et al., 1979; TURI ,1986; CHAFETZ & LAWRENCE,
1994).

The typical range from -2‰ to +8‰, of δ1 3C
values in travertines, is interpreted to reflect the conta-
mination of the isotopic composition of groundwater by
the bedrock marine limestones or juvenile/magmatic
waters (GO N F I A N T I N I et al., 1968; FR I E D M A N, 1970; TU R I,
1986; GUO et al., 1996). It is worth noting that soil deri-
ved carbon has never been reported from thermal
groundwater composition (PENTECOST, 2005). 

The contribute of recycled isotopes is also sup-
ported by the proximity of the distribution field of the
isotopic values of travertines and recent marine carbo-
nate sediments and older limestones (Fig: 5), which
records similar evaporative conditions of calcium car-
bonate precipitation in warm marine waters and also
the recycling through dissolution, of the heavier fossil
13C isotope. This specific distribution of stable isotopic
values of travertine, while attesting the thermal imprint
of the carbonate parent fluids, register dominantly phy-
sico-chemical precipitation of carbonates and a rele-
vant contribution of ions deriving from carbonate
bedrock and/or juvenile/magmatic waters.

4. CALCAREOUS TUFA

Present day riverine/palustrine systems where
calcareous tufa are actively forming (the Diborrato
water system - Fig. 2a, c, d - in Colle Val d'Elsa area,
near Siena is an instructive example), are fed by carbo-
nate-rich waters of meteoric derivation mostly rising
from karstic springs, or in some cases resulting at least
in part, from diluted and cooled, originally thermal
waters (CAPEZZUOLI et al., 2008). The mean temperature
of groundwaters at the emergence of karstic springs is
on average, cooler (2°C lower in the Dinaric Karst; HOR-

VATINCIC et al., 2003) than the flowing waters from which
tufa precipitates. However it rapidly equilibrates with
the local atmospheric temperature that is influenced by
seasonal changes and controlled by the latitudinal posi-
tion and global climatic regime. The subaerial circula-
tion of cool/ambient temperature waters, promote the
development of vegetation and subsequent precipita-

130 A. Gandin & E. Capezzuoli



131

Fig. 3 - Combined plot of δ18O (SMOW/PDB) and δ13C (PDB) values derived from travertine sampled in selected active thermal localities
of the world. Data sources: Yellowstone (Angel Terrace - FOUKE et al., 2000; Main spring - FRIEDMAN, 1970); Bagni San Filippo (Siena,
Italy) (GONFIANTINI et al., 1968); Le Zitelle (Viterbo, Italy) (CHAFETZ & LAWRENCE, 1994); Terme San Giovanni (Siena, Italy) (GUO et al., 1996);
Acqua Borra (Siena, Italy)(unpublished data); Alicun de la Torres (Spain) (JIMENEZ DE CISNEROS et al., 2006).
Diagramma combinato dei valori di δ18O (SMOW/PDB) e δ13C (PDB) di travertini campionati in alcune località termali attive nel mondo.
Dati ricavati da: Yellowstone (Angel Terrace - FOUKE et al., 2000; Main spring - FRIEDMAN, 1970); Bagni San Filippo (Siena Italia) (GONFIANTINI

et al., 1968); Le Zitelle (Viterbo, Italia) (CHAFETZ & LA W R E N C E, 1994); Terme San Giovanni (Siena, Italia) (GU O et al., 1996); Acqua Borra
(Siena, Italia) (dati originali); Alicun de la Torres (Spain) (JIMENEZ DE CISNEROS et al., 2006).

tion of calcium carbonate that however show a low-rate
production.

The removal of CO2 from flowing or standing
waters is controlled by the dominant action of physical
processes as vaporization/evaporation combined with a
minor contribution from the biologic/photosynthetic
activity of the emerged vegetation. In places where the
energy of the waters is higher, the tumultuous and more
copious release of CO2 stimulates the development of
luxuriant vegetation. Emergent as well as aquatic plants
and reeds, colonies of microbes, mosses and algae
settle preferentially on raised irregularities of the stream
bottom and on dam/barrages rims. Vaporization/out-
gassing processes enhanced by the irregularly scatte-
red vegetal clusters and thickets acting as obstacles to
the current flux (Fig. 2a,b), lead to the gradual, more or
less pervasive calcification of massive pillow-like phy-
tohermal/stromatolitic edifices (Fig. 2a, b,  c).

Filaments, stems and rows of green organic mat-
ter progressively encrusted by microcrystalline or larger
crystals of limpid prismatic calcite can be detected
within “ancient” as well as in “living” (Fig. 2e,f) phy-

tohermal deposits. In the backward floodbasins delimi-
ted by phytohermal barrages, rather quiet palustrine-
/lacustrine-like conditions of sedimentation occur.
Chara meadows and concentrations of diatoms someti-
mes develop on the bottom floored by lime mud with a
characteristic peloidal fabric.

The typical porous/chalky fabric consists of
microcrystalline, low-Mg calcite and peloidal aggrega-
tes of abiotic and biotic production. Abundant vegetal
remains are preserved mainly as casts of fragments
and parts of macrophytes or as filaments encased
within limpid calcite spar (Fig. 2e, f). Remains of inverte-
brates are frequently found. Many of the vegetation
components are organisms such as diatoms and chara-
ceans that favour cool fresh-waters and
mosses/Bryophytes that cannot tolerate temperatures
higher than 20°C (GL I M E & VI T T, 1984). Therefore the
biologic contribution in the precipitation of carbonates
in the riverine/palustrine system where macrophytes
prosper, results to be mainly a passive role of support
controlled by the availability of meteoric water.

The sedimentary architecture resulting from this

Travertine versus Calcareous tufa ...



depositional system defines the carbonate lithotype
designated as calcareous tufa. It consists of highly
porous, poorly bedded, irregularly staked lenticular
bodies of massive phytohermal or stromatolitic buildu-
ps (Fig. 2c) associated with thin lenticular layers of
unsorted phytoclastic sands and/or mud-supported
pond-related sediments (BU C C I N O et al., 1978; D'AR G E-

NIO et al., 1983; FERRERI 1985; BRANCACCIO et al., 1986;
D'ARGENIO & FERRERI, 1988; VIOLANTE et al., 1994; 1996).

The environmental requirements for the deposi-
tion of calcareous tufa are ultimately regulated by cli-
matic local or global conditions (HO R V A T I N C I C et al. ,
2003).

Geochemical analyses of presently forming calca-
reous tufa have been performed on samples collected
from several riverine/stream systems in central-northern
Europe. The parent water temperatures of the studied
carbonate samples (Fig. 4), range from average 10°C in
northern/central Europe up to 20°C in the Mediter-
ranean area (9°C in Poland and UK, THORPE et al., 1980;
PAZDUR et al., 1988; ANDREWS et al., 1994; GARNETT et al.,
2004; 10°C in Germany and Belgium, AN D R E W S et al. ,
1994; JANSSEN & SWENNEN, 1997; 15°C in Spain, SANCHO

et al., 1997; ANDREWS et al., 2000; ARENAS et al., 2000;
PEÑA et al., 2000).

Stable isotopic data obtained from the calcite
precipitated from cool spring/stream waters in these
localities, have been plotted on a Cartesian coordinate
system where it is possible to observe that the δ13C ver-
sus δ18O PDB values all falls in the same field of distri-
bution characterized by negative δ13C values (Fig. 4). 

The typical range of δ1 3C values in calcareous
tufa, from -11‰ to -5‰, reflect the outgassing of
already light 12C of meteoric and soil derivation (PENTE-

C O S T, 2005), since the preferential uptake of 1 2C by
green plants through photosynthetic action does not
appear to affect the overall carbon distribution and
removal in a freshwater system (USDOWSKI et al., 1979;
CHAFETZ & LAWRENCE, 1994; ANDREWS et al., 2000). 

The δ18O (PDB) values ranging from -3‰ to -12‰,
register cool temperature and saturation levels of the
spring waters (GONFIANTINI et al., 1968; USDOWSKI et al.,
1979; TURI ,1986; CHAFETZ & LAWRENCE, 1994) and con-
sequently record the properties of the local climatic
regime (HORVATINCIC et al., 2003).

Stable isotopes value of the calcareous tufa
essentially reflects the composition of the parent karstic
water which ionic content mainly results from isotopical-
ly light, soil derived CO2 contained in recharging meteo-
ric waters. A minor input of heavier recycled 1 3C derives
from dissolution of the marine carbonate bedrock (HO R-

V A T I N C I C et al., 2003), but has no influence in the isotopic
distribution (Fig. 5). Consequently, the specific distribu-
tion of the stable isotopic values of calcareous tufa,
while attesting the cool, fresh-water karstic and ultima-
tely meteoric imprint of the carbonate parent fluids, cor-
roborates also the dominantly passive biological contri-
bution to the precipitation of calcium carbonate, and
cool climatic conditions at the time of deposition.

5. CONCLUSION

Travertine and calcareous tufa are flowstones that
form under open-air conditions at the emergence of

thermal springs or along fluvial valleys/cool water
springs systems: two distinct geomorphologic settings
fed from groundwaters that after a non comparable
recharge/circulation pathway, emerge with different
mineral content and different temperatures. On the sur-
face the flow of warm-to-hot or cool/ambient tempera-
ture waters produce contrasting biological responses: a
bare white desert around thermal springs or luxuriant
vegetation along the stream valley. The lithologic featu-
res and isotopic signature of travertine and calcareous
tufa, closely record the specific physico-chemical com-
position and biologic imprint of the related depositional
environments. Criteria for the univocal definition of cal-
careous tufa and travertines can be acquired through
the comparison of the characteristics of the respective
present day depositional settings, the lithologic/petro-
graphic features and related isotopic signature of the
carbonates in formation.

Travertines deposited in thermal spring systems,
are characterized by warm-to-hot water supersaturated
with calcium bicarbonate and free CO2. Outgassing and
vaporizing/cooling processes combined with turbulence
and velocity of the flow control the shape and distribu-
tion of the sedimentary bodies. They consist of well
bedded, finely laminated, dominantly crystalline crusts
often associated with calcified-bubble facies, paper-
thin rafts, and in the distal part, with peloidal aggrega-
tes and bacterial/cyanobacterial laminites. Travertine
depositional features and the positive field of distribu-
tion of δ13C register the dominant control of the physi-
co-chemical parameters: temperature, evaporation and
outgassing, on calcite precipitation. The hot, supersatu-
rated carbonate waters rising from deep subsurface cir-
culation through a network of extensional faults are in
part of meteoric derivation and in part of recycled, juve-
nile geothermic/magmatic provenance.

Calcareous tufa develop in fluvio-palustrine
systems fed by cool, carbonate-rich waters mainly of
karstic and meteoric origin. In evident contrast with the
thermal system where life is limited to mainly heat-
loving bacteria, in the fluvio/palustrine conditions luxu-
riant vegetation of micro- and macrophytes results from
the opportunistic colonization of water-rich environ-
ments where large amounts of CO2 are available. The
irregular distribution of the sedimentary bodies along
the valleys and their petrologic features, reflect the phy-
sico-chemical properties of the water and hydrodyna-
mics of the flow. Highly porous, poorly bedded, irregu-
larly staked phytohermal or stromatolitic buildups and
lenticular layers of unsorted phytoclastic sands and/or
mud-supported pond-related sediments, characterize
the tufa lithofacies. Microcrystalline calcite, peloidal
aggregates and/or limpid spar are the dominant fabrics.

The negative field of distribution of stable isoto-
pes values of calcareous tufas essentially reflects the
parental relationships with the meteoric and soil-deri-
ved karstic waters and a minor input of heavier recycled
carbon. The vegetation involvement in the formation of
calcareous tufa appears to be limited to a passive role
of support more than an active involvement in the che-
mical biogenic precipitation of calcium carbonate.
Accordingly, the development of calcareous tufa
appears to be controlled by the availability of meteoric
water and ultimately by local/global climatic conditions. 

Facies analysis and petrographic characterization

132 A. Gandin & E. Capezzuoli



of the present day terrestrial limestones forming from
flowing waters in subaerial settings, evidence the unmi-
stakable differences in fabrics, lithofacies and biologic
involvement in the deposition of travertine and calca-
reous tufa. Likewise, the fields of distribution of the δ13C
and δ1 8O isotopic values of recent deposits of well

known origin appear to be rather well correlated with
the distinctive environmental conditions and petro-
graphic features of each group: they reflect unrelated
physico-chemical conditions of the fluids feeding the
two depositional systems.

The distribution field of the stable isotopes of tra-

133

Fig. 4 - Combined plot of δ18O (SMOW/PDB) and δ13C (PDB) values derived from tufa and speleothems in formation, sampled in selec-
ted localities of central-north Europe. Data sources: Poland (PAZDUR et al., 1988); Dinaric area (HORVATINČ IĆ et al., 2003); UK/Belgium
(ANDREWS et al., 1994; THORPE et al., 1980; JANSSEN & SWENNEN, 1997; GARNETT et al., 2004); Spain (PEÑA et al., 2000; SANCHO et al., 1997; ARENAS

et al., 2000; ANDREWS et al., 2000); Trentino (Italy) (FRISIA, 2003); Postojna Karst (HORVATINČIĆ et al., 2003); Westerhof (Germany) (USDOWSKI et
al., 1979).
Diagramma combinato dei valori di δ18O (SMOW/PDB) e δ13C (PDB) ricavati da calcareous tufa e speleotemi in formazione, campionati
in alcune località dell'Europa centro-settentrionale. Dati ricavati da: Polonia (PAZDUR et al., 1988); Area Dinarica (HORVATINČIĆ et al., 2003);
GB/Belgio (ANDREWS et al., 1994; THORPE et al., 1980; JANSSEN & SWENNEN, 1997; GARNETT et al., 2004); Spagna (PEÑA et al., 2000; SANCHO et
al., 1997; ARENAS et al., 2000; ANDREWS et al., 2000); Trentino (Italia) (FRISIA, 2003); Grotte di Postumia (HORVATINČIĆ et al., 2003); Westerhof
(Germania) (USDOWSKI et al., 1979).

Travertine versus Calcareous tufa ...



vertine appears to be wider than that of calcareous
tufa. It probably reflects the more ample range of tem-
perature, dept of circulation, volcanic or groundwater
sources of the travertine-related waters, while the kar-
stic-meteoric waters of the calcareous tufa records
more uniform climate-related conditions.

ACKNOWLEDGMENTS

We would like to thank the anonymous reviewers
for pertinent suggestions that improved the final version
of this paper. This work has been financially supported
by the University of Siena 2005 PAR grant (A. Gandin). 

134

Fig. 5 - Combined plot of δ18O (SMOW/PDB) and δ13C (PDB) values derived from carbonates presently forming in terrestrial (travertine,
calcareous tufa, speleothems) and marine (skeletal-ooid sediments and pelagic muds) environments and from lithified marine limesto-
nes. Data sources for travertine see Fig. 2. Data sources for tufa and speleothems see Fig. 4. Data sources for marine limestones,
recent calcareous sediments and meteoric cements: NELSON & SMITH (1996 with references therein).
Diagramma combinato dei valori δ18O (SMOW/PDB) e δ13C (PDB) dei carbonati attualmente in formazione in ambiente continentale (tra-
vertini, calcareous tufa, speleotemi), e marino (depositi scheletrici, ad ooidi e fanghi pelagici): Sono inclusi per confronto anche i valori
dei calcari marini litificati e dei cementi di origine meteorica. Per dati sui travertini vedi Fig. 2. Per i dati sui calcareous tufa e gli speleo-
temi vedi Fig. 4. Per i carbonati marini, e i cementi meteorici vedi NELSON & SMITH (1996) cum bibl.

A. Gandin & E. Capezzuoli



REFERENCES

ALTUNEL E. (2005) - Travertines: neotectonic indicators.
In: ÖZKUL M., YAGIZ S., JONES B. (eds). Travertine,
Proceedings of 1s t International Symposium on
Travertine, September 21-25, 2005, Denizli-
Turkey, 120-127, Kozan Ofset, Ankara.

ANDREWS J.E. (2005) - Paleoclimatic records from stable
isotopes in riverine tufas: synthesis and review.
Earth-Science Reviews, 75, 85-104. 

ANDREWS J.E., PEDLEY H.M. & DENNIS P.F. (1994) - Stable
isotope record of palaeoclimate change in a
British Holocene tufa. Holocene, 4, 349-355.

AN D R E W S J.E., PE D L E Y H.M. & DE N N I S P.F. (2000) -
Palaeoenvironmental records in Holocene Spanish
tufas: a stable isotope approach in search of relia-
ble climatic archives. Sedimentology, 4 7, 961-
978.

ARENAS C., GUTIÉRREZ F., OSÀCAR C. & SANCHO C. (2000) -
Sedimentology and geochemistry of fluvio-lacu-
strine tufa deposits controlled by evaporite solu-
tion subsidence in the central Ebro Depression,
NE Spain. Sedimentology, 47, 883-909.

BARAZZUOLI P., COSTANTINI A., FONDI R., GANDIN A., GHEZ-

Z O C., LA Z Z A R O T T O A., MI C H E L U C C I NI M., SA L L E O L I N I

M. & SALVADORI L. (1988) - I travertini di Rapolano
sotto il profilo geologico e geologico-tecnico. In
CO L I V. (a cura di): Il Travertino di Siena, Ed.
Al.Sa.Ba Grafiche, Siena, 26-35.

BRANCACCIO L., D'ARGENIO B., FERRERI V., PREITE MARTINEZ

M., STANZIONE D. & TURI B. (1986) - Caratteri tessi-
turali e geochimica dei travertini di Rocchetta a
Volturo (Molise) . Bollett ino della Società
Geologica Italiana, 105, 265-277.

BROGI A. & CAPEZZUOLI E. (2008) - Travertine deposition
and faulting: the fault-related travertine fissure-
ridge at Terme S. Giovanni, Rapolano Terme
( I t a l y ). Int. J. Earth Sci. (Geol Rundsch), DOI
10.1007/s00531-007-0290-z

BROGI A., CAPEZZUOLI E., COSTANTINI A., GANDIN A. & LAZ-

ZAROTTO A. (2005) - Tectonics and travertines rela-
tionships in the Rapolano Terme area (Northern
Apennines, Italy). In: ÖZKUL M., YAGIZ S., JONES B.
(eds). Travertine, Proceedings of 1s t I n t e r n a t i o n a l
Symposium on Travertine, September 21-25,
2005, Denizli-Turkey, 142-148, Kozan Ofset,
Ankara.

BU C C I N O G., D'AR G E N I O B., FE R R E R I V., BR A N C A C C I O L . ,
FERRERI M., PANICHI C. & STANZIONE D. (1978) - I tra-
vertini della bassa Val Tanagro (Campania): studio
geomorfologico, sedimentologico e geochimico.
Bollettino della Società Geologica Italiana, 9 7,
617-646.

CAPEZZUOLI E. & GANDIN A. (2004) - I “travertini” in Italia:
proposta di una nuova nomenclatura basata sui
caratteri genetici. Il Quaternario, 17(2/1), 273-284.

CA P E Z Z U O L I E. & GA N D I N A. (2005) - Facies distribution
and microfacies of thermal-spring travertine from
T u s c a n y. In: M. Ozkul, S. Yagiz, B. Jones Eds.,
Travertine, Proceedings of 1s t I n t e r n a t i o n a l
Symposium on Travertine, September 21-25,
2005, Denizli-Turkey, 43-49, Kozan Ofset, Ankara.

CA P E Z Z U O L I E.,  GA N D I N A. & SA N D R E L L I F.  (2008) -
Evidence of associated deposition of travertine

and calcareous tufa in the Quaternary carbonates
of Valdelsa Basin (Tuscany). Il Quaternario,
21(1B), 113-124.

CHAFETZ H.S. & FOLK R.L. (1984) - Travertines: depositio-
nal morphology and the bacterially constructed
costituents. J. Sedim. Petrol., 54, 289-316.

CH A F E T Z H.S. & LA W R E N C E J.R. (1994) - Stable isotopic
variability within modern travertines. Géographie
Phys. et Quatern., 48(3), 257-273.

CILLA G., COLTORTI M. & DRAMIS F. (1994) - Holocene flu-
vial dynamics in mountain areas: the case of the
river Esino (Appennino Umbro-marchigiano).
Geografia Fisica e Dinamica Quaternaria, 17, 163-
174.

D'ARGENIO B. & FERRERI V. (1988) - Ambienti deposizio-
nali e litofacies dei travertini quaternari dell'Italia
c e n t r o - m e r i d i o n a l e . Memorie della Società
Geologica Italiana, 41, 861-868.

D'ARGENIO B., FERRERI V., STANZIONE D., BRANCACCIO L. &
FE R R E R I M. (1983) - I travertini di Pontecagnano
(Campania): geomorfologia, sedimentologia, geo-
c h i m i c a . Bollett ino della Società Geologica
Italiana, 102, 123-136.

DU B A R M. (2006) - Recherche et interpretation climati-
que des microcycles du concretionnement traver-
tineux de l 'aqueduc romain de Frejus (Var,
France). Quaternaire Paris, 17, 79-85.

FACCENNA C., FUNICIELLO R., MONTONE P., PAROTTO M. &
VO L T A G G I O M. (1994) - An example of late
Pleistocene strike-slip tectonics: the Acque Albule
basin (Tivoli, Latium). Memorie descrittive della
Carta Geologica d'Italia, XLIX, 63-76.

FERRERI V. (1985) - Criteri di analisi di facies e classifica-
zione dei  travertini  pleistocenic i dell 'I ta lia
M e r i d i o n a l e. Rend. Acc. Scienze Fis. e Mat., 5 2,
Napoli. 47 pp.

FORD T. D. & PEDLEY H.M. (1996) - A review of tufa and
travertine deposits of the world. Earth Sci. Rev.,
41, 117-175.

FO U K E B.W., FA R M E R J.D., DE S MA R A I S D.J., PR A T T L . ,
STURCHIO N.C., BURNS P.C. & DISCIPULO M.K. (2000)
- Depositional facies and aqueous-solid geoche-
mistry of travertine-depositing hot spring (Angel
Terrace, Mammoth Hot Spring, Yellowstone
National Park, U.S.A.). Journal of Sedimentary
Research, 70(3), 565-585.

FRIEDMAN I. (1970) - Some investigation of the deposition
of travertine from Hot Springs-I. The isotopic che-
mistry of a travertine-depositing spring. Geoch.
Cosmoch. Acta, 34, 1303-1315.

FR I S I A S. (2003) - Le tessiture negli speleotemi. Studi
Trent. Sci. Nat., Acta Geol., 80, 85-94.

GANDIN A., CAPEZZUOLI E. & CIACCI A. (2006) - The stone
of the Etruscan inscribed steles from the Valdelsa
area (Siena, Italy). In: MA G G E T T I M. & ME S S I G A B .
(eds.). Geomateria ls in Cultural Heri tage.
Geological Society, London, Special Publications,
257, 273-282.

GARNETT E.R., ANDREWS J.E., PREECE R.C. & DENNIS P.F.
(2004) - Climatic change recorded by stable isoto-
pes and trace elements in a British Holocene tufa.
Journal of Quaternary Science, 19, 251-262.

GLIME J.M. & VITT D.H. (1984) - The physiological adap-
tations of aquatic Musci. Lindbergia, 10, 41-52.

GO N F I A N T I N I R., PA N I C H I C. & TO N G I O R G I E. (1968) -

135Travertine versus Calcareous tufa ...



Isotopic disequilibrium in travertine deposition.
Earth and Planetary Science Letters, 5, 55-58.

GUO L., ANDREWS J., RIDING R., DENNIS P. & DRESSER Q.
(1996) - Possible microbial effects on stable
Carbon Isotopes in Hot-Spring travertines. J. Sed.
Res., 66(3), 468-47.

GUO L. & RIDING R. (1998) - Hot-spring travertine facies
and sequences, late Pleistocene, Rapolano
Terme, Italy. Sedimentology, 45, 163-180.

GU O L. & RI D I N G R. (1999) - Rapid facies change in
Holocene fissure ridge hot spring travertines,
Rapolano Terme, Italy. Sedimentology, 46, 1145-
1158.

HAMMER O. DYSTHE D.K. & JAMTVEIT B. (2007) - The dyna-
mics of travertine dams. Earth and Planetary
Science Letters, 256, 258-263.

HA N C O C K PL., CH A L M E R S RML, AL T U N E L E., ÇA K I R Z .
(1999) - Travitonics: using travertines in active
fault studies. Journal of Structural Geology, 2 1,
903-916.

HO R V A T I NČIĆ N., BR O NIĆ I .K. & OB E LIĆ, B. (2003) -
Differences in the 1 4C age, δ1 3C and δ1 8O o f
Holocene tufa and speleothems in the Dinaric
K a r s t . Palaeogeography, Palaeoclimatology,
Palaeoecology, 193, 139-157.

JANSSEN A. & SWENNEN R. (1997) - Petrography and geo-
chemistry of the travertine deposit at Treignes (S.
B e l g i u m ) . Bulletin de la Societe Belge de
Geologie, 106, 97-115.

JIMENEZ DE CISNEROS C., CABALLERO E. & JIMENEZ-LOPEZ C.
(2006) - δ1 8O and δ13C of modern/ancient traveti-
nes from a thermal spring (Alicun de las Torres,
Southern Spain). Geoacta, 5, 13-24.

JU L I À R. (1983) - T r a v e r t i n e s . In: P.A. SC H O L L E , D . G .
BE B O U T, C.H. MO O R E (Eds): Carbonate Depositio-
nal Environments. AAPG Memoir, 33, 62-72.

MERZ-PREISS M. & RIDING R. (1999) - Cyanobacterial tufa
calcification in two freshwater streams: ambient
environment, chemical thresholds and biological
processes. Sedimentary Geology, 126 (1-4), 103-
124.

MINISSALE A., KERRIK D., MAGRO G., MURRELL M.T., PALADI-

N I S., RI H S S,. ST U R C H I O N., TA S S I F. & VA S E L L I O .
(2002) - Structural hydrogeological chemical and
climatic parameters affecting the precipitation of
travertines in the Quaternary along the Tiber val-
ley, north of Rome. Earth Planet. Sci. Lett., 2 0 3,
709-728.

NE L S O N C.S. & SM I T H A.M. (1996) - Stable oxygen and
carbon isotope compositional fields for skeletal
and diagenetic components in New Zealand
Cenozoic non tropical carbonate sediments and
limestones: a synthesis and review. New Zealand
Journal of Geology and Geophysics, 39, 93-107.

ÖZKUL M., VAROL B. & ALÇIÇEK M.C. (2002) - Depositional
Environments an petrography of Denizli Travertine.
Bullettin of the Mineral Research and Exploration,
125, 13-29.

PAZDUR A., PAZDUR M.F. STARKEL, L. & SZULC J. (1988) -
Stable isotopes of Holocene calcareous tufa in
southern Poland as palaeoclimatic indicators.
Quaternary Research, 30, 177-189.

PE D L E Y H.M. (1990) - Classification and environmental
models of cool freshwater tufas. Sedim. Geol., 68,
143-154.

PEDLEY H.M., ANDREWS J., ORDÒÑEZ DELGADO S., GAR-

CIA DEL CURA M.A., GONZÀLEZ MARTÌN J.A. & TAYLOR

D. (1996) - Does climate control the morphological
fabric of freshwater carbonates? A comparative
study of Holocene barrages tufas from Spain and
B r i t a i n. Paleogeography, Paleoclimatology,
Paleoecology, 121, 239-257.

PE Ñ A J.L., SA N C H O C. & LO Z A N O M.V. (2000) - C l i m a t i c
and tectonic significance of Pleistocene and
Holocene tufa deposits in the Mijares River
canyon, eastern Iberian range, Northeast Spain.
Earth Surface Processes and Landforms, 2 5,
1403-1417.

PENTECOST A. (1995) - The quaternary travertine deposits
of Europe and Asia Minor. Quat. Sci. Rev., 1 4,
1005-1028.

PENTECOST A. (2005) - Travertine. 445 pp. Springer 
PE N T E C O S T A. & VI L E S H.A. (1994) - A review and reas-

sessment of travertine classification. Geographie
physique et Quaternaire, 48, 305-314.

RI D I N G R. (1991) - Classi fication of Microbial
Carbonates. - In: RIDING R. (Ed) : Calcareous algae
and stromatolites. 21-51, Springer-Verlag.

SANCHO C., PEÑA J.L. & MELENDEZ A. (1997) - Controls on
Holocene and present-day travertine formation in
the Guadalaviar River (Iberian Chain, NE Spain).
Zeitschrift für Geomorphologie, 41, 289-307.

SH I P T O N Z.K., EV A N S J.P., KI R S C H N E R D., KOLESAR P . T . ,
WI L L I A M S A.P. & HE A T H J.E. (2004) - Analyses of
C O2 leakage through “low-permeability” faults
from natural reservoirs in the Colorado Plateau,
east-central Utah. Journal of Geological Society of
London, Special Publication, 233, 43-58.

SI B S O N R.H. (2000) - Fluid involvement in normal
faulting. Journal of Geodynamics, 29, 469-499.

TH O R P E P.M., OT L E T R.L. & SW E E T I N G M.M. (1980) -
Hydrobiological implications of 14C profiling of UK
tufa. Radiocarbon, 22, 897-908.

TURI B. (1986) - Stable isotope geochemestry of traverti-
nes. In: P. FRITZ & J.C. FONTES (Eds) - Handbook of
Environmental  Isotope Geochemestry. 2 .
Terrestrial Environment, B. Elsevier, Amsterdam,
pp. 207-238.

US D O W S K I E. , HO E F S J. & ME N S C H E L G. (1979) -
Relationship between 13C and 18O fractionation and
changes in major element composition in a recent
calcite-depositing spring - a model of chemical
variations with inorganic CaCO3 p r e c i p i t a t i o n.
Earth and Planetary Science Letters, 42, 267-276.

VI O L A N T E C., FE R R E R I V. & D'AR G E N I O B. (1996) -
Modificazioni geomorfiche controllate dalla depo-
sizione di travertino. Il Quaternario, Italian Journal
of Quaternary Sciences, 9(1), 213-216.

VI O L A N T E C., FE R R E R I V. & D'AR G E N I O B. & GO L U B I C S .
(1994) - Quaternary travertines at Rocchetta a
Volturno (Isernia, Central Italy). Facies analysis and
sedimentary model of an organogenic carbonate
system. I.A.S. 15th Reg. Meet., April, 1994, Ischia,
Guide book to the field trip, 3-23.

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Ms. ricevuto il 22 febbraio 2008
Testo definitivo ricevuto il 21 marzo 2008

Ms. received: February 22, 2008
Final text received: March 21, 2008

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