Facies

DOI 10.1007/s10347-011-0266-0

ORIGINAL ARTICLE

Facies evolution and sequence chronostratigraphy of a “mid”-Cretaceous shallow-water carbonate succession of the Apulia Carbonate Platform from the northern Murge area (Apulia, southern Italy)

Luigi Spalluto

Received: 27 July 2010 / Accepted: 3 January 2011© Springer-Verlag 2011

Abstract The “mid”-Cretaceous carbonate succession ofthe Apulia Carbonate Platform cropping out in northernMurge area (Apulia, southern Italy) is composed of shal-low-water carbonate rocks and is over 400 m in thickness.This paper focuses on the lithofacies analysis of this car-bonate succession, its paleoenvironmental interpretation,and its sequence-chronostratigraphic architecture. Lithofa-cies analysis permitted to identify deposits which can begrouped into the following three facies belts: (1) terrestrialfacies belt formed by: intraclast-supported paleosoils; solu-tion-collapse breccias; (2) restricted facies belt made up oflithofacies deposited in protected peritidal environments;(3) normal-marine facies belt made up of lithofacies formedin moderate- to high-energy subtidal environments. Thedetailed study both in outcrops and in thin-sectionsrevealed that, at the bed scale, lithofacies are cyclicallyarranged and form shallowing-upward small-scale deposi-tional sequences comparable to parasequences and/or sim-ple sequences. The following three small-scale sequencetypes have been distinguished: (1) subtidal sequencesmostly made up of lithofacies formed in the normal-marineopen subtidal domain; (2) peritidal sequences made up oflithofacies formed in the restricted peritidal domain; (3)peritidal sequences showing a cap formed by paleosoils.Small-scale sequences are not randomly arranged in thecompiled succession but form discrete packages, or sets,that alternate in the sedimentary record. The repetition of

such small-scale sequence packages in the succession hasbeen the key to recognize large-scale sequences compara-ble to third-order depositional sequences. Although sedi-mentological data are often fragmentary due to latedolomitization, four large-scale sequences have been distin-guished. The data support a generalized landward-back-stepping of facies belts during transgression, which impliesa gradual gain of accommodation culminating with thedeposition of a package of small-scale sequences formed bynormal-marine subtidal deposits. These mark periods ofmaximum accommodation space and form the maximum-Xooding zones of large-scale sequences. A gradual seawardprogradation of facies belts is recorded during highstandconditions, which implies a gradual loss of accommodationculminating with the deposition of a package of peritidalsmall-scale sequences capped by paleosoils or by solution-collapse breccias. The occurrence of terrestrial depositsmarks periods of minimum accommodation on the platformand determines the sequence boundary of large-scalesequences. The large-scale sequences identiWed in thisstudy Wt with the main transgressive/regressive cycles pub-lished in the sequence-chronostratigraphic chart of Euro-pean basins. As a consequence, it is interpreted thatchanges of the sea level recorded at the scale of Europeanbasins played an important role in determining thesequence-stratigraphic architecture of the studied succes-sion. In spite of this, the occurrence of solution-collapsebreccias, which implies a signiWcant gap in carbonate sedi-mentation in between Early and Middle Cenomanian times,may also have an alternative interpretation. In particular,this deposit may represent the local Wngerprint of the well-known tectonic phase which, during Late Albian-Early/Middle Cenomanian times, determined the subaerial expo-sure of large parts of Periadriatic carbonate platforms pro-ducing a marked regional unconformity.

L. Spalluto (&)Dipartimento di Geologia e GeoWsica, Università degli Studi di Bari “Aldo Moro”, Via E. Orabona 4, 70125 Bari, Italye-mail: l.spalluto@geo.uniba.it

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Keywords Shallow-water carbonates · Sequence chronostratigraphy · “Mid”-Cretaceous · Apulia Carbonate Platform · Murge area · Southern Italy

Introduction

The “mid”-Cretaceous sedimentary succession of the Apu-lia Carbonate Platform cropping out in the Murge area(Apulia, southern Italy) is mainly composed of shallow-water carbonate rocks (e.g., Ricchetti 1975; CiaranW et al.1988; Spalluto et al. 2008). These carbonates form well-bedded and laterally continuous beds deposited in tropical-water environments that can be compared to present-dayshallow-water carbonate environments of the Bahamas(Eberli et al. 1993). The succession is rather monotonousand mostly consists of peritidal and shallow subtidal car-bonate lithofacies associations (Spalluto et al. 2008). Onlya few stratigraphic intervals contain more open- anddeeper-marine lithofacies associations in which abundantand diversiWed associations of rudists and benthic forami-nifera were found (Gallo Maresca 1994; Spalluto et al.2008). These intervals are fundamental in determining thechronostratigraphy of the studied succession since thestratigraphic distribution of benthic foraminifera assem-blages is the only available biostratigraphic tool for the dat-ing of these shallow-water limestones.

This paper is mainly Weld-based and represents a Wrstattempt to interpret gradual changes in lithofacies stacking-patterns of the Apulia Carbonate Platform using asequence-stratigraphic approach. The focus is on the depo-sitional architecture of large-scale (third-order) deposi-tional sequences, their chronostratigraphic evolution, andtheir correlation with main transgressive/regressive cyclespublished in the sequence-chronostratigraphic chart estab-lished for European basins (Hardenbol et al. 1998).

The vertical stacking of meter-scale sequences in shal-low-water carbonate successions leads to larger sequencescomparable to third-order sequences (Strasser et al. 2000)showing again a repetitive occurrence of depositional andearly diagenetic features. Since such sequences have anaggradational architecture, diagnostic geometries for mar-ginal-marine sequences (such as onlap, oZap, toplap stratalrelationships) cannot be recognized, limiting the applica-tion of classic sequence-stratigraphic paradigms. In spite ofthis, sequences boundaries, systems tracts, and transgres-sive and maximum Xooding surfaces are likely to be recog-nized applying a detailed lithofacies analysis (Goldhammeret al. 1990, 1993; D’Argenio et al. 1997, 1999; Strasseret al. 1999). SpeciWcally, diagnostic surfaces or intervalsare a proxy to interpret the sequence stratigraphy and canbe identiWed by tracing deepening-upward or shallowing-upward trends of lithofacies evolution in packages of

meter-scale sequences (sequence stratigraphy of gradualchanges sensu Schlager 2005).

The cyclic occurrence of depositional and diageneticfeatures in meter-scale peritidal sequences is the most com-mon stratigraphic feature of ancient shallow-water carbon-ate successions formed on Xat-topped platforms (e.g., Jonesand Desrochers 1992). These sequences correspond to abed or to groups of a few beds and display a dominant shal-lowing-upward trend, which is expressed by a gradualchange from deeper to shallower lithofacies, or by a diage-netic supratidal overprint of subtidal lithofacies (Strasser1994). Meter-scale sequences reXect short-term variationsin accommodation space, comparable to the forth- to Wfth-order parasequences (sensu Van Wagoner et al. 1988) orsimple sequences (sensu Vail et al. 1991). They stack intolower-order large-scale sequences (transgressive/regres-sive facies trends sensu D’Argenio et al. 1999), reXectinglong-term variations in accommodation space, comparableto the third-order depositional sequences of Vail et al.(1991).

Geological setting

The studied succession crops out in the northern part of theMurge area (Apulia, southern Italy, Fig. 1). The Murgearea is an autochthonous region and is considered as partof the extensive and only slightly deformed foreland area(Apulian foreland sensu Selli 1962; D’Argenio et al. 1973;Ricchetti et al. 1988) of the southern Apennines chain(Fig. 1). The sedimentary succession cropping out in theMurge area is mainly composed of 3,000-m-thick Creta-ceous shallow-water limestones and dolostones forming aS-SW dipping monocline slightly deformed by folds andsub-vertical normal and transtensional faults (Festa 2003and references therein). This carbonate succession wasdeposited mainly in low-energy shallow-water environ-ments (e.g., Ricchetti 1975; CiaranW et al. 1988; Spallutoet al. 2005, 2007, 2008) that developed in the interior ofthe Mesozoic Apulia Carbonate Platform (ACP), whichwas one of the Periadriatic platforms (D’Argenio 1974;Zappaterra 1990). Periadriatic platforms were sites ofnearly exclusive shallow-marine carbonate sedimentationfrom Late Triassic to the end of the Cretaceous (e.g.,Ricchetti et al. 1988; Zappaterra 1990). They where intra-oceanic platforms located at the northern margin of theAfrican Plate (the African Promontory sensu Channelet al. 1979) in the western sector of the Tethys ocean. Inthis paleogeographic context, thermal subsidence wascompensated by enough sedimentation to keep the plat-form growing in a passive-margin setting (Channel et al.1979; Ricchetti et al. 1988). Nevertheless, during Middle/Late Cretaceous times, when collision between Africa and

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Eurasia began, the Periadriatic region was involved in thedeformation process induced by the propagation of theintraplate stress during the early phase of the alpineorogenesis (e.g., Eberli 1991; Mindszenty et al. 1995).Tectonic deformation of carbonate platforms produced twomajor regional intra-Cretaceous unconformities pointingto long-lasting subaerial exposures, the former Albian/Cenomanian in age, the latter Turonian in age (e.g.,Mindszenty et al. 1995). The sedimentary record of theACP records only the Turonian event since no signiWcantrecord of subaerial exposures occurs in Albian and Ceno-manian deposits (Valduga 1965; Ricchetti 1975).

Stratigraphy

Lithostratigraphy

The studied succession is over 400 m thick (Fig. 2) andbelongs to the middle/upper part of the Calcare di Bari Fm(Valduga 1965; Ricchetti 1975). It is almost completelymade up of parallel-bedded limestones with frequentintercalations of dolostones. The limestones are mainlymud-supported with a poorly diVerentiated microfossilif-erous assemblage, in which small-sized benthic foramini-fers, calcareous algae, and ostracodes prevail. The

Fig. 1 a Location of the Apulian foreland in a synthetic structural map of Italy. b SimpliWed geologic map of the Apulia region. c Geologic crosssection through the Murge area (modiWed from Pieri et al. 1997). The rectangle outlines the study area

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mud-supported deposits commonly alternate with lami-nated microbial limestones and less frequently with intra-clastic breccias locally containing black pebbles (Spallutoet al. 2008). Dolostones prevail in some intervals of thesuccession forming massive banks often devoid of inter-nal bedding. They formed during late diagenesis, which

could lead to the almost complete obliteration of the orig-inal texture.

The relative facies monotony of the Calcare di Bari Fmis interrupted by two groups of beds rich in macrofossilsand by a massive layer made up of dolomitic breccias. Thegroups of beds correspond to the reference levels of the

Fig. 2 Stratigraphic log of the studied succession showing lithofacies and sequence-stratigraphic interpretation (SB sequence boundary; TD trans-gressive deposits; MF maximum Xooding; HD highstand deposits)

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Calcare di Bari Fm (Valduga 1965; Azzaroli and Valduga1967; Azzaroli et al. 1968; Boenzi et al. 1971; Ricchetti1975; Spalluto and CaVau 2010) that, within the studiedsuccession, are informally known as the “Palese level”(Late Albian in age) and the “Sannicandro level” (Middle/Late Cenomanian in age). The “dolomitic breccia level”(Early/Middle Cenomanian in age) is characterized by oneprevailing lithofacies. All these levels have a regionalextent and they can be mapped and laterally traced for sev-eral tens of kilometers in the whole Murge area (Ricchetti1975).

The “Palese level” is located in the lower part of thestudied succession and consists of an about 25-m-thickinterval characterized by rudist-dominated medium- tocoarse-grained deposits. Rudists form dm- to m-thick sheet-like tabular bodies, are laterally traceable, loosely packed(isolated), and the shells are whole, in growth position ormore commonly randomly oriented (Fig. 3a). The matrix ofthe rudist-rich layers is composed of medium- to coarse-grained bioclastic calcarenites and calcirudites with a rela-tive wide range of skeletal particles (mostly molluscs and

benthic foraminifers). In many beds of the “Palese level”rudist assemblages alternate with bioclastic calcarenitesshowing high-energy sedimentary structures such as gradedbeds, grain imbrication, and parallel to cross lamination.The following association of rudists characterizes thismarker layer (Gallo Maresca 1994): Eoradiolites murgen-sis, Eoradiolites lyratus, Apricardia sp.

The “dolomitic breccia level” is located in the middlepart of the succession and consists of an about 20-m-thickinterval made up of chaotically arranged dolomitic brecciasin a microcrystalline dolomitic matrix (Fig. 3b). The brec-cias are made up of dark gray diVerently sized (from a fewcentimeters to a few meters) clasts and do not show an evi-dent organization in beds.

The “Sannicandro level” is located in the upper part ofthe studied succession and consists of an about 20-m-thickinterval, in which rudist- and ostreid-dominated depositsoccur (Fig. 3c). Similarly to the “Palese level”, rudists andostreids form dm- to m-thick sheet-like and laterally trace-able layers, in which shells are arranged in autochthonousor parautochthonous loosely packed assemblages and lack

Fig. 3 Lithostratigraphic units of the Calcare di Bari Fm: a “Paleselevel”: in situ assemblage of randomly oriented radiolitids.b “dolomitic breccia level”: chaotically arranged diVerently sized

dolomitic clasts in a microcrystalline dolomitic matrix (bigger clastsare outlined by a black line). c “Sannicandro level”: coarse-grained bi-oclastic layer made up of radiolitid fragments

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evidence of a signiWcant transport. The matrix is made upof medium-grained deposits in which mollusc fragments,intraclasts, peloids, and benthic foraminifers are present.The following association of rudists and ostreids character-izes this marker level (Azzaroli et al. 1968): Eoradiolitessp., Chondrodonta joannae, Apricardia laevigata.

Biostratigraphy

Based on the stratigraphic distribution of benthic foramini-fers, Wve associations were identiWed in the studied succes-sion (Spalluto and CaVau 2010) (Fig. 2):

a1 —This association occurs in the Wrst 10 m of the stud-ied succession and is deWned by the concomitant occur-rence of the following taxa: Cuneolina sliteri,Cuneolina pavonia, Cuneolina parva, Praechrysali-dina infracretacea (Fig. 4a), Sabaudia minuta, Novale-sia angulosa, Nezzazatinella picardi, Nezzazataisabellae, Vercorsella arenata, and Vercorsella scar-sellai. The association of these taxa supports an Early/Middle Albian age according to VeliT (2007) but, inthis paper, a late Middle Albian age is proposed due tothe stratigraphic position of this association, which liesbelow the orbitolinid-rich assemblage of the associa-tion a2.

a2 —This association occurs from about 10 to 85 m in thesuccession. It is deWned by the concomitant occurrenceof two main taxa: “Valdanchella” dercourti (Fig. 4b)and Neoiraqia insolita, which represent valid biostrati-graphic markers. Associated fauna are ParacoskinolinaXeuryi, Praechrysalidina infracretacea, Nezzazata isa-bellae, Nezzazatinella picardi, and Cuneolina parva.This association supports a Late Albian age followingHusinec and Sokac (2006) and VeliT (2007).

a3 —This association occurs from about 120 to 180 m inthe succession. It is deWned by the concomitant occur-rence of two main taxa: Protochrysalidina elongata(Fig. 4c) and Neoiraqia cf. convexa. Praechrysalidinainfracretacea and Nezzazatinella picardi complete theassociation. This association supports the latest Albian(Vraconian) age, according to Mezga et al. (2007).

a4 —This association occurs from about 195 to 255 m inthe succession. It is deWned by the occurrence of thefollowing taxa: Sellialveolina viallii (Fig. 4d), Cuneo-lina pavonia, Nezzazatinella picardi, Nezzazata sim-plex and Pseudonummoloculina heimi. It has an EarlyCenomanian age following Chiocchini et al. (1984),VeliT and VlahoviT (1994) and VeliT (2007).

a5 —This association occurs from about 340 to 450 m inthe succession. It is deWned by the concomitant occur-rence of the following taxa: Chrysalidina gradata(Fig. 4e), Biconcava bentori, Trochospira avnimelechi,

Pseudorhapydionina dubia (Fig. 4f), Biplanata pene-ropliformis, Broeckina (Pastrikella) balcanica, Cisal-veolina fraasi, Nezzazatinella picardi, Nezzazataconica, Nezzazata simplex, Cuneolina pavonia, Pseud-onummoloculina heimi, Pseudolituonella reicheli, andVidalina radoicicae. This association supports a Mid-dle-Late Cenomanian age following Chiocchini andMancinelli (1977), De Castro (1988), VeliT and Vlah-oviT (1994), Luperto Sinni (1996), Husinec et al.(2000) and VeliT (2007).

Lithofacies analysis and environmental interpretation

The lithofacies analysis is based on the recognition offacies constituents, texture, fossil content, and early diage-netic overprint. Field observations and microfacies analysisperformed on 435 thin-sections permitted to distinguisheight lithofacies grouped in three lithofacies associations(A, B, and C), interpreted to represent three facies beltsformed in terrestrial, peritidal, and open-lagoon environ-mental domains. The study and interpretation of lithofaciesand lithofacies associations form the basis for the identiW-cation of depositional sequences.

A1 Dolomitic breccia

Description: This lithofacies is about 20 m thick and occursin the middle part of the studied succession. In the studiedsuccession, it corresponds to the “dolomitic breccia level”of the Calcare di Bari Fm (Fig. 2) and is made up of eitherclast-supported or matrix-supported intraclastic breccias.The breccias are monomictic with angular, diVerently sized(from a few millimeters to tens of centimeters) dolomiticclasts (Fig. 3b) and can be classiWed as “unsorted mono-mictic chaotic rubble breccia” (Morrow 1982) showinglimited or no transport. The matrix corresponds to amicrobreccia or to Wne-crystalline dolomite. The wholebrecciated interval shows a stratiform geometry with well-deWned boundaries.

Environmental interpretation: The interpretation of thislithofacies is quite controversial. Ricchetti (1975) suggeststhat this type of dolomitic breccias might develop in hyper-saline environments. The dolomitic breccias are then inter-preted as solution-collapse breccias caused by thedissolution of evaporitic layers, interbedded with dolomitebeds (e.g., Assereto and Kendall 1977; Eliassen and Talbot2005). This interpretation cannot be fully supported in thispaper since no direct or indirect evidence of the depositionof primary evaporitic layers has been found. In spite of this,these breccias show strong evidence (chaotic arrangement,no deWnable bedding, limited or no transport) that indicatean in situ formation. Therefore, as a possible alternative

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interpretation, this lithofacies may be interpreted as apaleokarst breccia formed during mid-Cenomanian times bypervasive meteoric dissolution of dolomitized beds. In this

context, brecciation of dolomitic beds might be the result ofthe collapse of a karstic cave system during a prolonged sub-aerial exposure phase (e.g., Esteban and Klappa 1983).

Fig. 4 Benthic foraminifer assemblages of the studied succession.a Association a1: Praechrysalidina infracretacica, longitudinal sec-tion. b Association a2: “Valdanchella” dercourti, longitudinal section.c Association a3: Protochrysalidina elongata, longitudinal section.

d Association a4: Sellialveolina vialii, mainly axial section and Cune-olina pavonia, longitudinal and basal section. e Association a5: Chry-salidina gradata, longitudinal-slightly oblique section. f Associationa5: Pseudorhapydionina dubia, longitudinal section

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A2 Intraclastic breccia

Description: This lithofacies is present in the lower and inthe middle part of the succession (Fig. 2) where it formstwo laterally continuous layers at the scale of the outcrop(few tens of meters). In both cases, each layer marks abreak in shallow-marine carbonate sedimentation. Intra-clastic breccias are arranged in dense grain-supportedassemblages and form layers in which two parts with adiVerent degree of cementation can be distinguished(Fig. 5a). The lower part is chalky and intraclasts areembedded in a greenish or light brown silty-clayey matrixand are arranged in sheet-like horizons. Intraclast rework-ing is absent. This part grades downward into the underly-ing rock through a transition zone showing strong evidenceof in situ alteration and brecciation. The upper part is wellcemented and thus stands out as a prominent feature since itis more resistant to weathering than the underlying part.Among intraclasts, black pebbles are abundant and locallygrouped together to form dark layers mostly concentratedin the uppermost part of the well-cemented interval(Fig. 5b). The matrix is commonly made up of clottedpeloidal microcrystalline calcite showing root casts Wlledby dark micrite, cylindrical to irregular pores Wlled by spa-rite, and circum-granular cracks. Intraclasts of thecemented interval may be also found reworked at the baseof the overlying bed, embedded in a shallow-marine car-bonate matrix.

Environmental interpretation: This lithofacies is inter-preted as having formed in supratidal environments proba-bly adjacent to a tidal Xat area. The lower chalky part maycorrespond to the early stage in the formation of a soil oncarbonate rocks (Esteban and Klappa 1983). This part pre-serves relics of the original sedimentary structures, such asbedding, and contains evidence of in situ alteration and par-tial replacement of the original material. In this speciWccase, weathering produced both pervasive brecciation of theoriginal material and accumulation of the residual silty-clayey detritus. The upper well-cemented part may corre-spond to the mature stage in the formation of a soil sinceprecipitation of calcium carbonate leads to the lithiWcationand fossilization of the soil proWle and formation of a hard-pan (Esteban and Klappa 1983). The presence of black peb-bles conWrms this interpretation since they are consideredas important markers for partial or complete subaerialexposure (Strasser and Davaud 1983; Flügel 2004) and fre-quently occur in carbonate soils (Esteban and Klappa1983).

B1 Fenestral wackestone/packstone and bindstone

Description: This lithofacies is made up of wackestonesand packstones with peloids, micritic intraclasts, grape-

stones, mollusk fragments, small-sized miliolids, tufts ofporostromate cyanobacteria, Thaumatoporella sp., andostracodes characterized by millimeter- to centimeter-sizedfenestral cavities. Smaller fenestrae (birdseyes) form lami-noid or irregularly distributed spheroidal spar-Wlled cavitiesand are often associated with microbial bindstones(Fig. 5c); larger ones form a dense network of irregularlyshaped voids (stromatactoid fabric) locally Wlled with Wne-grained geopetal sediments (vadose silt sensu Dunham1969) at the base and sparry calcite at the top (Fig. 5d). Theupper part of the larger cavities may show microstalactiticcements. Locally, shrinkage cracks occur at the top of thislithofacies.

Environmental interpretation: Fenestal limestones have apolygenic origin and may be caused by: (a) wetting anddrying of carbonates in upper intertidal/lower supratidalenvironments (Shinn 1968); (b) drying of cyanobacterialmats (e.g., Hardie and Shinn 1986); (c) degassing of decay-ing organic material (Shinn 1983). Fenestrae were pre-served during the early stages of the diagenesis and arepartly Wlled by microstalactitic cements and geopetal inter-nal sediments in the voids. Although fenestral limestonesmay form in diVerent environments, their occurrencetogether with early diagenetic vadose features, microbialbindstones, and mud cracks constrain the interpretation toupper intertidal/lower supratidal environments (e.g., Shinn1983).

B2 Peloidal mudstone/wackestone with rare fossils

Description: This lithofacies is predominantly made up ofpelleted lime mudstones and wackestones in which onlysparse small-sized thin-shelled ostracodes, miliolids, andgastropods may be recognized (Fig. 5e). These micrites arealways homogenized by burrowing and lack primary sedi-mentary structures. This lithofacies has a typical mottled-gray color.

Environmental interpretation: Pelleted micrites withoutfossils or with reduced benthic biota are usually diagnosticcriteria of low-energy restricted shallow-lagoon

Fig. 5 Platform interior lithofacies of the studied succession.a Lithofacies A1: intraclastic breccias arranged in dense grain-sup-ported assemblages showing two parts with a diVerent degree ofcementation. The lower one is chalky while the upper one is wellcemented (hardpan) and contains black pebbles. b Lithofacies A1: blackpebble layer at the top of the well-cemented part. c LithofaciesB1: microbial bindstones showing irregularly distributed spheroidalspar-Wlled fenestrae. d Lithofacies B1: fenestral packstone showingirregularly distributed voids with geopetal Wllings. e LithofaciesB2: partly dolomitized mudstone with a small gastropod. f LithofaciesB3: packstone made up of micritic intraclasts, peloids, miliolids, cal-careous algae. g Lithofacies C1: grainstone made up of aggregategrains (grapestones), small-sized benthic foraminifers and peloids.h Lithofacies C2: packstone with mollusc fragments and benthic fora-minifers (mostly orbitolinids)

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environments characterized by critical values of tempera-tures and/or salinities and by oxygen depletion (Enos1983).

B3 Miliolid-ostracode-algal wackestone/packstone

Description: This lithofacies is mostly made up of stronglyburrowed wackestones, packstones, and subordinatelygrainstones with benthic foraminifers (typical are miliolids,cuneolinids, textularids), ostracodes, calcareous algae, req-uienids, gastropods, Thaumatoporella sp., small-sized onc-oids, micritic intraclasts, and peloids (Fig. 5f). Biota show areduced diversity but commonly with a high number ofindividuals. Usually, fecal pellets Wll burrows.

Environmental interpretation: Taking into account:(a) the limited number of grain types; (b) the absence ofgrain reworking, abrasion, rounding, and sorting; (c) thereduced diversity of exclusively benthic biota but relativelygreat number of those few organisms adapted to survive;(d) the reduced size of individuals (dwarf fauna); (e) thelack of desiccation structures and other features indicatingtidal Xat environment (e.g., microbial laminae and/or fenes-trae), this lithofacies is interpreted as deposited in low-energy semi-restricted shallow-subtidal environments.

C1 Aggregate-grain and biopeloidal packstone/grainstone

Description: This lithofacies is made up of aggregate-grainand biopeloidal packstones/grainstones mostly made up ofmicritized aggregate grains (lumps) in association withmicritized skeletal grains (rudists and gastropods), micriticintraclasts, small-sized benthic foraminifers, dasycladaceanfragments, porostromate oncoid and peloids (Fig. 5g).Aggregate grains predominantly consist of lumps, showingthe characteristic lobate outline (grapestone), made up ofsmall bioclasts and peloids bound together by microcrystal-line calcite. Most grains show an isopachous rim of earlymarine cement. Coarser crystals of equant calcite Wll inter-particle and intraparticle pores. Facies constituents areoccasionally arranged in parallel-to-undulated laminationsand show prevailingly normal gradation.

Environmental interpretation: The grain-supported tex-tures, the presence of high-energy sedimentary structures,and the normal grading of grains permit the interpretation ofthis lithofacies as deposited in shallow wave- or current-agi-tated open-lagoonal environments where migrating sandbarscould form. The occurrence of a normal-marine and diversi-Wed benthic fauna also supports this interpretation.

C2 Foraminiferal wackestone/packstone

Description: This lithofacies is made up of burrowed fora-miniferal wackestones, packstones, and subordinately

grainstones showing a moderate species diversity. Thedominant biota are benthic foraminifers among which orbi-tolinids, alveolinids, cuneolinids, miliolids, and textularidsare abundant (Fig. 5h). Bioeroded fragments of dasyclada-cean algae and molluscs (mostly bivalves and gastropods),grapestones, cortoids, and peloids are also important con-tributors.

Environmental interpretation: This lithofacies, whencompared to previous lithofacies, shows a higher speciesdiversity, which indicates deposition in normal-marinelagoonal environments not subjected to signiWcant restric-tion in water circulation. In this environment, the mainsource of carbonate sediment was represented by the accu-mulation of foraminiferal tests.

C3 Molluscan Xoatstone/rudstone

Description: This lithofacies is made up of mollusc-bearingXoatstones and rudstones in a bioclastic wackestone/pack-stone or packstone/grainstone matrix (Fig. 3a, c). In thestudied succession, it occurs in beds of the “Palese” and“Sannicandro” levels of the Calcare di Bari Fm (Fig. 2).The dominant biota are rudists (mostly radiolitids and req-uienids) in association with gastropods. Rudist-dominatedassemblages occur in sheet-like concentrations in whichindividuals are loosely packed and completely lack mutualsupport. Typically, rudist shells lack the upper valve andare in growth position or, more commonly, slightly oblique(with random orientation of tests). The coarse sandy matrixconsists of skeletal fragments, which derived from bioero-sion and mechanical breakdown of rudist shells, only occa-sionally showing a micritic envelope (cortoids). Associatedare benthic foraminifers, fragments of dasycladacean algaeand echinoids, solitary corals, grapestones, and micriticintraclasts. Peloids occur only rarely.

Environmental interpretation: The relatively high fossildiversity and abundance is consistent with deposition innormal-marine lagoonal environments with low to moder-ate water energy conditions. These environments corre-sponded to rudist-inhabited sand plains, in which the mainsource of carbonate sediment was represented by the frag-mentation of rudist shells.

Depositional model

The lithofacies have been grouped in three facies belts, andcompared with facies belts 7, 8, and 9 of the standard faciesmodel of Wilson (1975) with modiWcations of Flügel(2004) and Schlager (2005) and thus referred to the samenumber of respective environmental domains that devel-oped in a tropical-type platform-interior depositional sys-tem isolated from terrigenous inputs.

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Facies

Low-energy muddy peritidal deposits (lithofacies associ-ation B) characterized the innermost sectors of the platforminterior (Fig. 6). Peritidal limestones contain a relativelypoor and dwarfed benthic biotic assemblage, suggestingrestricted conditions in water circulation due to poor con-nection with the open ocean, which caused large variationsin water temperatures and salinities. Intertidal/supratidaldeposits (lithofacies B1) show meteoric cements, geopetalvadose silt and mud cracks indicating periodic subaerialexposure. Moving seaward, restricted deposits pass intodeeper and more open ones, which formed in lagoons suY-ciently connected with the open ocean to preserve normal-marine salinity and temperature close to that of tropicaloceans. As a result, in this setting, an abundant and diversi-Wed stenohaline fauna (mostly rudists and benthic foramini-fers) developed in moderate energy environments. Thedeposition of relatively coarser and laminated deposits(lithofacies C1) reXects relatively higher-energy conditionsalong a belt of migrating sand bars caused by wave and/or

current energies transporting sediment. The occurrence ofwell-developed terrestrial deposits, locally represented bycollapse breccias (lithofacies A1) and paleosoils (lithofa-cies A2), testiWes that shallow-water carbonate sedimenta-tion was aVected by signiWcant breaks. These gaps insedimentation are related to relative sea-level falls able toperiodically expose the platform for a time span longenough to develop karstic processes and pedogenesis.According to Birkeland (1999), soil processes on carbonaterocks occur at a considerably low rate and usually takethousands of years (see also Wright 1996; D’Argenio et al.1997).

Small-scale depositional sequences

In the studied succession, the vertical organization of lithof-acies and lithofacies associations results in small-scale(from a few dm- to a few m-thick) sequences displaying a

Fig. 6 Depositional model showing the paleoenvironmental interpretation of lithofacies forming the studied succession (modiWed from Read1985)

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Facies

cyclic occurrence of depositional and early diagenetic char-acteristics. Each sequence usually corresponds to an indi-vidual bed and shows an initial thin deepening trend,followed by a thicker and much better developed shallow-ing trend (shallowing-upward subtidal and peritidalsequences according to Enos 1983; James 1984; Osleger1991, among many others). Sequence boundaries corre-spond to bed surfaces and display evidence of either sub-aerial or submarine exposure and also normally correspondto subtidal, intertidal, or supratidal surfaces that cap theshallowest lithofacies of each sequence (Strasser et al.1999). A thin lag of reworked intraclasts locally marks theearly transgressive phases in the formation of small-scalesequences. Transgressive deposits are indicated by thedeepening-upward trend in lithofacies. In many cases, thisinterval is either thin or absent and when absent the rela-tively most open lithofacies directly lie at the base of thesequences. Highstand deposits of small-scale sequences arealways well developed since they are indicated by the dom-inant shallowing-upward trend of lithofacies.

According to their lithofacies evolution, three mainkinds of small-scale depositional sequences can be recog-nized (Fig. 7): (A) subtidal sequences, (B) peritidalsequences, and (C) peritidal sequences capped by paleo-soils.

Subtidal sequences

Small-scale subtidal sequences are composed entirely bylithofacies formed in the lagoonal domain (lithofacies asso-ciation C). From bottom to top, in each subtidal sequenceonly a shallowing-upward trend in lithofacies assemblagesis recorded. This trend is marked by the gradual changefrom molluscan Xoatstones (lithofacies C3) to foraminif-eral-rich packstones (lithofacies C2). This trend culminateswith the deposition, on top of subtidal sequences, of lami-nated biopeloidal packstones/grainstones (lithofacies C1)deposited in higher-energy conditions (migrating shoalbars). Incomplete subtidal sequences lack this high-energycap. Sequence boundaries correspond to sharp surfacesmarking a rapid deepening underlined by the restoration ofmolluscan-inhabited open-lagoon environments. As a con-sequence, small-scale subtidal sequences may be ascribedto parasequences since, according to the original deWnitionof Van Wagoner et al. (1988), they are bounded by marineXooding surfaces.

Peritidal sequences

Small-scale peritidal sequences are formed by lithofaciesdeposited entirely in the peritidal domain (lithofacies asso-ciation B). The base of these sequences containsreworked deposits mostly formed by a few-mm to a few-cm

intraclast-bearing lags. An initial deepening-upward trendis marked by the gradual transition from reworked depositsto miliolid-ostracode-algal limestones (lithofacies B2),indicating restricted subtidal environments. The followingshallowing-upward trend is always well developed and typ-ically marked by the gradual transition from restricted sub-tidal limestones (lithofacies B2 and B3) to intertidal/supratidal ones (lithofacies B1). Sequence boundaries ofperitidal sequences correspond to sharp surfaces recordingevidence of subaerial exposure. Subaerially exposed lime-stones (lithofacies B1) are typically aVected by vadose dia-genesis (vadose cap) and, as a consequence, show a well-developed fenestral fabric and pervasive recrystallization ordolomitization. As a consequence, these small-scalesequences can be compared to the simple sequences of Vailet al. (1991), since they are bounded by surfaces formed insubaerial conditions. Peritidal sequences represent the larg-est parts of the identiWed sequences and show the most fre-quent occurrence along the investigated succession.

Peritidal sequences capped by paleosoils

Small-scale peritidal sequences capped by paleosoils showan incomplete shallowing-upward tendency in lithofaciesevolution as intertidal lithofacies are missing. Restrictedsubtidal limestones are cut by a surface recording exposurefeatures (e.g., root traces and brecciation), and desiccationpolygons). Paleosoils (lithofacies A2) cover the boundingsurfaces. According to D’Argenio et al. (1997, 1999), thedevelopment of such exposure surfaces, showing a deeppenetration of meteoric overprint in underlying deposits,suggests a more prolonged subaerial exposure associatedwith major sedimentary gaps in carbonate deposition. Aswith the previous sequence type, this sequence can also becompared to the simple sequences of Vail et al. (1991)since they are bounded by well-developed exposuresurfaces.

Origin of small-scale depositional sequences

The vertical stacking of meter-scale depositional sequencesis a very common characteristic of Xat-topped carbonateplatform successions and can be explained by autocyclicand/or allocyclic processes (e.g., Strasser 1991). The Wrstones depend on factors linked to normal sedimentary evolu-tion of the depositional system, the second ones depend onexternal factors totally independent from it.

In the studied succession, peritidal sequences may beexplained by an allocyclic process since they show a rela-tively abrupt deepening (i.e., lagoonal deposits directlysuperposed to supratidal ones) and then a gradual shoalingtrend related to the progradation of tidal Xat deposits over

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Facies

adjacent lagoonal deposits (e.g., Ginsburg 1971). Neverthe-less, this process may be excluded as the main controllingfactor in the formation of both subtidal and peritidalsequences capped by paleosoils for the following reasons:(a) the occurrence of subtidal sequences implies that sedi-mentation rate was not high enough to Wll all the availableaccommodation space (Osleger and Read 1991); (b) thesuperposition of terrestrial deposits directly on lagoonal

sediments implies a relative sea-level drop and then a pro-longed subaerial exposure (e.g., D’Argenio et al. 1997). Asa result, it is interpreted that high-frequency relative sea-level changes in concert with the local rates of carbonateaccumulation played an important role in the formation ofthe three diVerent types of small-scale sequences.

The origin of high-frequency relative sea-level changesis commonly explained by allocyclic processes and the

Fig. 7 Sketch showing lithofacies evolution of the three diVerent types of shallowing-upward, small-scale, depositional sequences identiWed inthe studied succession

Subtidal sequence

m w p g f/r

open lagoon

open lagoon

shoal

shoal

shal

low

ing-

upw

ard

Peritidal sequence

inter/supratidal

restricted lagoon

restricted lagoon

shal

low

ing-

upw

ard

inter/supratidal

transgr. lag deposit

transgr. lag deposit

Peritidal sequence capped by paleosoil

m w p g f/r

restricted lagoon

restricted lagoon

shal

low

ing-

upw

ard

paleosoil

paleosoil

m w p g f/r

lithofacies C1

lithofacies C2

lithofacies C1

lithofacies C3

lithofacies C3

lithofacies B1

lithofacies B2

lithofacies B1

lithofacies B3

lithofacies B3

lithofacies A1

lithofacies A1

lithofacies B2

lithofacies B1

lithofacies B3

lithofacies B3

subaerial exposure

transgr. lag deposit

subaerial exposure

fenestrae

microbial mat

Facies elements

benthic foraminiferthaumatoporellaceangastropod

Keys and symbols

burrowing

Sedimentary structures

Textures m mudstone/bindstone w wackestone p packstone g grainstone f/r floatstone/rudstone

rudistostracod

parallel lamination

erosive surface

LithologyLimestone

Residual clays

peloid

intraclastic layer

black pebble layer

desiccation features

from

30

cm to

120

cm

from

30

cm to

100

cm

from

90

cm to

250

cm

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Facies

discussion focuses on tectonic vs. eustatic control. In thestudied succession, a tectonic control may be excluded forthe following reasons: (a) there is no evidence in the stud-ied area of periodic pulses of downfaulting (e.g., Cisne1986) that would have repeatedly created accommodationspace for the small-scale sequences. Moreover, these eventsshould be limited close to the fault zone and could notexplain the widespread extent of sequences across theentire platform (e.g., Grotzinger 1986; Strasser 1991);(b) regardless of the regional tectonic setting, it is hard toinvoke high-frequency cyclic tectonic pulses generating avertical stacking of meter-scale sequences like thosedescribed in this paper (e.g., Osleger and Read 1991).

As a consequence, it is interpreted that high-frequency,orbitally forced, relative sea-level changes probably in theMilankovitch frequency band may be considered the maincontrolling factors in the formation of small-scalesequences. Nevertheless, autocyclic processes cannot betotally excluded as contributors of the internal variability ofindividual sequences (Osleger 1991).

This interpretation agrees with several cyclostratigraphicstudies (e.g., D’Argenio et al. 1997, 1999; Spalluto 2008among many others) performed on several Cretaceous plat-form carbonate successions cropping out in southern Apen-nines and formed in the same paleotectonic andpaleogeographic context in which deposited the studiedsuccession.

Large-scale depositional sequences

The sedimentary record of the studied succession is formedby complex packages, or sets, of small-scale sequences.These small-scale sequences may be viewed as the buildingblocks of larger sequences showing again deepening-upward and shallowing-upward trends of lithofacies evolu-tion (Fig. 2). Deepening-upward trends are interpreted astransgressive deposits of large-scale sequences and arecharacterized by: (a) stacking of small-scale sequencesfrom those formed exclusively by peritidal lithofacies asso-ciations towards those formed by open subtidal lithofaciesassociations; (b) general upward-increasing thickness ofsmall-scale sequences. The maximum-Xooding zone (thezone where the relatively deepest or most open-marinelithofacies associations occur, and/or reduced sedimenta-tion rate according to Montañez and Osleger 1993andStrasser et al. 1999) of large-scale sequences correspondsto the thickness of those few beds formed by rudist-richsubtidal small-scale sequences occurring on top of thedeepening-upward interval. Shallowing-upward trends areinterpreted as highstand deposits of large-scale sequencesand are characterized by: (a) upward stacking of small-scale sequences from those formed by open subtidal

lithofacies associations to those formed exclusively inrestricted peritidal lithofacies associations; (b) generalupward-decreasing thickness of small-scale sequences.Sequence boundaries of large-scale sequences correspondto the thickness of those few beds formed by peritidalsequences capped by paleosoils (sequence boundary zonesin Fig. 2) or to the top of a massive interval made up ofsolution-collapse breccias.

Although the occurrence of several dolomitized intervalsdoes not always permit a continuous lithofacies record, fourlarge-scale sequences, labeled from 1 to 4, have been deW-ned in the studied succession (Fig. 2).

Sequence 1

This sequence (S1) is incomplete since only the upper part(about 10 m in thickness) crops out in the studied succes-sion. This part of S1 records a shallowing-upward trend oflithofacies evolution. This trend is underlined by the occur-rence of a package of peritidal sequences showing a thin-ning-upward stacking pattern of peritidal sequences and anupward-increasing enhancement of desiccation features(i.e., thicker vadose cap) recorded on top of each peritidalsequence. This interval corresponds only to the upper partof highstand deposits of S1 (Fig. 2). As a matter of fact,such types of small-scale sequences imply an importantloss of the accommodation space on the platform due to aseaward shift of the shoreline and the subsequent exposureof wide sectors of the inner part of the platform for a timespan long enough to induce soil-forming processes. As aresult, these three sequences are considered as the sequenceboundary zone of S1. This sequence boundary marks alsothe local last occurrence in the succession of several fora-miniferal taxa. The following species: Cuneolina sliteri,Cuneolina parva, Sabaudia minuta, Novalesia angulosa,Nezzazata isabellae, Vercorsella arenata, and Vercorsellascarsellai found in association a1 (Fig. 2), well recorded inAptian-Lower/Middle Albian limestones of the Apulia Car-bonate Platform (Luperto Sinni and Masse 1992), do notsurvive this important event.

Sequence 2

This sequence (S2) begins with a package of small-scaleperitidal sequences showing a deepening-upward trend oflithofacies evolution. This trend is recorded as a thickening-upward stacking pattern of small-scale sequences showingan upward-decreasing of early vadose diagenesis. Com-monly, for each successive small-scale sequence, the thick-ness of the subtidal lithofacies (lithofacies B2) increasesand, at the same time, subaerial exposure occurs at a pro-gressively later stage, reXecting a gradual gain in accom-modation space. The deepening-upward trend in lithofacies

123

Facies

assemblages culminates with a 20-m-thick interval made upof small-scale subtidal sequences. This interval is inter-preted as the maximum Xooding zone of the S2. This inter-pretation is supported by the fact that small-scale subtidalsequences are exclusively made up of open subtidal depos-its (lithofacies association C) suggesting that, at that time,the platform was extensively Xooded. Rudist-rich bedsbelonging to the informal lithostratigraphic unit of the Cal-care di Bari Fm locally named “Palese level” formed dur-ing this period (Fig. 2). The shallowing-upward trend of S2is much more developed since it is about 130 m thick andrecords the gradual evolution from subtidal to peritidalsmall-scale sequences. This trend marks the gradual disap-pearance in the succession of open-marine lithofacies dueto a general decrease in the accommodation space. Peritidallithofacies dominated this interval and represent the typicalsedimentary signature of highstand deposits of S2; at thesame times, open-shelf lithofacies probably developed onlyseaward in limited areas close to the margin of the plat-form. As with S1, the sequence boundary zone of S2 isunderlined by a few small-scale peritidal sequences cappedby paleosoils.

Sequence 3

This sequence (S3) is 70 m thick and shows an initial deep-ening-upward trend that culminates with the deposition ofsmall-scale subtidal sequences showing a rich content inbenthic foraminifer assemblages. The maximum-Xoodingzone of this sequence corresponds to the occurrence ofsmall-scale subtidal sequences, suggesting that the platformwas characterized by normal-marine subtidal environments.This interpretation is also supported by the Wrst occurrencein the succession of primitive alveolinids, adapted to sur-vive in normal-marine waters. The shallowing-upward partof S3 is partly hidden by late dolomitization, while theupper part records an approximately 20-m-thick intervalmade up of solution-collapse breccias (lithofacies A1). Thislithofacies marks a period of prolonged subaerial exposureand its top represents the sequence boundary of S3.

Sequence 4

This sequence (S4) is incomplete, since the upper part isnot recorded in the studied succession. The outcroppingpart of S4 is about 170 m thick, the lowest 50 m of whichare obliterated by late dolomitization. Similar to S2 and S3,the maximum-Xooding zone of S4 is underlined by theoccurrence of small-scale subtidal sequences locally corre-sponding to rudist-rich beds of the “Sannicandro level”.Although the shallowing-upward part of S4 is not com-pletely outcropping, it is proposed that the sequence bound-ary of S4 corresponds to an important phase of subaerial

exposure marked in the Murge area by the deposition ofbauxites and terra rossa deposits (Crescenti and Vighi1964). This sequence boundary can be interpreted as a tec-tonically enhanced unconformity (sensu Jacquin et al.1991) since it is produced by regional uplifting that aVectedshallow-marine environments of the ACP in response to thepropagation, in distal domains, of the intraplate stress pro-duced by early phases of the Alpine orogenesis (Mindsz-enty et al. 1995).

Sequence-stratigraphic interpretation

The detailed lithofacies analysis performed on the studiedsuccession shows that facies belts in the platform interior ofthe ACP migrated several times landward and seaward.This resulted in the observed deepening-upward and shal-lowing-upward trends both at the bed scale (small-scalesequences) and at the bedset scale (large-scale sequences).Regarding the stratigraphic architecture of large-scalesequences, deepening-upward and shallowing-upwardtrends may be, respectively, assimilated to transgressivedeposits and highstand deposits of third-order depositionalsequences (e.g., Goldhammer et al. 1990, 1993; D’Argenioet al. 1999, 2004; Strasser et al. 2000). The basic buildingblocks of transgressive and highstand deposits are formedby shallowing-upward small-scale sequences, which repre-sent the composite sedimentary signature recorded by thedepositional system during short-term (high-frequency) rel-ative sea-level changes superimposed on an underlyinglong-term (low-frequency) signal.

Deepening-upward trends implies that facies belts grad-ually moved landward since the rate of accommodationgrowth exceeded the rate of sediment supply (Fig. 8). As aconsequence, each successive small-scale sequence is theproduct of building out into a relatively deeper lagoon dur-ing a continued long-term relative sea-level rise (Kendalland Schlager 1981; Handford and Loucks 1993; Schlager2005). The continued superposition of high-frequency sig-nals on the long-term rise built a sedimentary succession inwhich repetition of Xooding and catch-up sedimentationproduced an interval made up of a gradual evolution fromperitidal to subtidal-dominated sequences interpretable as aretrogradational small-scale sequence set. The relativelydeepest lithofacies associations developed on top of thissequence set forming a package of small-scale subtidalsequences interpreted as maximum-Xooding intervals(Figs. 2, 8). In addition, during transgressive times, benthicorganisms (rudists and benthic foraminifers) were able todiversify into various euphotic habitats, particularly withinshallow, open-lagoonal environments of the platform inte-rior setting. Qualitative analysis demonstrated that,throughout transgressive deposits, abundance and diversity

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Facies

Fig. 8 SimpliWed sequence stratigraphic model of the studied area and proposal of correlation with transgressive/regressive cycles of thesequence-chronostratigraphic chart (modiWed from Hardenbol et al. 1998)

123

Facies

of benthic organisms increased as an ecologic response tothe spreading of oligotrophic and stenohaline shallow-marine waters and reached the acme during times of maxi-mum Xooding.

Shallowing-upward trends indicate that facies belts grad-ually moved seaward, since the rate of sediment supplyexceeded the rate of accommodation creation. The resultingsedimentary record represents the product of the buildingout into shallower environments during a continued long-term highstand of relative sea level (Kendall and Schlager1981; Handford and Loucks 1993; Schlager 2005). Thecontinued superposition of the high-frequency signals onthe long-term highstand phase, produced highstand depositsmade up of progradational small-scale sequence set inwhich a gradual evolution from subtidal to peritidal-domi-nated small-scale sequences can be traced (Figs. 2, 8).Foraminiferal abundance and diversity decreased duringthe shallowing-upward trend as a response to the growingdegree of restriction in peritidal environments. The rela-tively shallowest lithofacies associations developed on topof this progradational sequence set forming either a pack-age of peritidal small-scale sequences capped by paleosoils(tops of S1 and S2 in Figs. 2, 8) or a massive layer of solu-tion-collapse breccias (top of S3 in Figs. 2, 8). The intervalsin which occur small-scale sequences capped by paleosoilsare interpreted as sequence boundary zones since theyformed during long-term sea-level fall, which produced ageneral loss of accommodation space resulting in periods ofsubaerial exposure marked by soil-forming processes. Inspite of this, it is worth to note that during this period therecord of small-scale sequences, although largely incom-plete, was not completely stopped because relatively higheramplitude high-frequency relative sea-level changes wereable to periodically Xood the platform creating a very fewaccommodation space for shallow-marine carbonates. Onthe contrary, the interval in which occurs solution collapsebreccias is interpreted as a period of prolonged and perva-sive meteoric dissolution of highstand carbonates duringwhich the record of small-scale sequences was completelystopped. In this case, the top of the brecciated interval isconsidered the sequence boundary of S3. As a result, thissequence boundary is interpreted as an important unconfor-mity whose hiatus falls in between Early and Middle Ceno-manian times (Fig. 8).

Sequence-chronostratigraphic correlation and origin of large-scale depositional sequences

Although the chronostratigraphic resolution of the studiedsuccession is not very precise as biostratigraphic data arebased only on the stratigraphic distribution of benthic fora-minifers, a tentative correlation is proposed between the

observed large-scale sequences and main long-term trans-gressive/regressive cycles published in the sequence-chro-nostratigraphic chart for European basins (Hardenbol et al.1998). A correlation has been proposed between thesequence boundary at the top of S1 with the Al 7 sequenceboundary of the chronostratigraphic chart, which marks thetransition between Middle and Late Albian times (Harden-bol et al. 1998) (Fig. 8). This correlation is supported by thelast occurrence of several Middle Albian taxa in late high-stand deposits of S1 (association a1 in Fig. 2) and by theWrst occurrence of Late Albian primitive orbitolinid assem-blages (association a2 in Fig. 2) in deepening-upward car-bonates of S2 above this sequence boundary zone. Acorrelation may be also proposed between the sequenceboundary zone at the top of S2 and the Al 11 sequenceboundary of chronostratigraphic charts, which falls imme-diately below the Albian/Cenomanian boundary (Harden-bol et al. 1998) (Fig. 8). This interpretation is supported bythe disappearance of all Albian species in the late highstandcarbonates of S2 and by the Wrst occurrence of LowerCenomanian taxa (see association a3 in Fig. 2) in transgres-sive carbonates of S3. A further correlation may be dubita-tively proposed between the sequence boundary of S3 andthe Ce3 sequence boundary, which marks the transitionbetween Early and Middle Cenomanian times (Hardenbolet al. 1998) (Fig. 8). This correlation may be supported bythe Wrst occurrence of Middle-Late Cenomanian taxa (asso-ciation a4 in Fig. 2) in transgressive carbonates of S4. Nev-ertheless, an alternative interpretation of this latter eventcannot be excluded. As a matter of fact, the massive layerof solution-collapse breccias marking the sequence bound-ary zone of S3 implies a prolonged subaerial exposure thatabruptly interrupted the record of small-scale sequences.This condition is not recorded through sequence boundaryzones of S1 and S2 where the high-frequency signal,although incomplete, is recorded by peritidal sequencescapped by paleosoils. This implies for sequence boundaryof S3 an important gap in carbonate sedimentation, whichprobably falls in between Early and Middle Cenomaniantimes (Fig. 8). As a working hypothesis, it is suggested thatthis prolonged interval of subaerial exposure may be corre-lated with the important tectonic phase, well recorded incentral-southern Apennines area, that during “mid”-Creta-ceous times aVected large areas of the Periadriatic carbonateplatforms resulting in a gap in carbonate sedimentation span-ning in age from Late Albian to Early/Middle Cenomanian(Eberli 1991; Mindszenty et al. 1995; Bernoulli et al. 1996;Vecsei et al. 1998 among others). This correlation contrastswith previous interpretation of stratigraphic data availablefor the “mid”-Cretaceous ACP succession cropping out inthe Murge area, which support an uninterrupted shallow-water carbonate sedimentation until Turonian times (e.g.,Ricchetti 1975). As a consequence, it is here proposed that

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Facies

an important “mid”-Cretaceous gap in shallow-water car-bonate sedimentation is recorded also in the Murge area,even if the time span not represented by carbonates isshorter than that recorded by coeval successions croppingout in central-southern Apennines.

The sequence-chronostratigraphic interpretation pro-posed in this paper permits to discuss the origin of large-scale sequences cropping out in the studied area. The goodWt between these sequences with those published in thesequence-chronostratigraphic chart of Hardenbol et al.(1998), suggests that long-term sea-level changes recordedat the scale of European basins played an important role indetermining the sequence-stratigraphic architecture dis-played by the studied succession. Nevertheless, it is notexcluded that the formation of the unconformity (sequenceboundary of S3) marked by solution-collapse breccias maybe controlled and/or enhanced by tectonics. As a matter offact, this event records a prolonged subaerial exposurephase of this sector of the ACP during times in which car-bonate platforms of the Periadriatic region were subaeriallyexposed as the consequence of the regional tectonic bulgingrelated to the early stage of the Alpine orogenesis (e.g.,Eberli 1991; Mindszenty et al. 1995).

Conclusions

The “mid”-Cretaceous shallow-water carbonate successioncropping out in the studied area is a typical example of atropical-type Xat-topped carbonate platform that developedin a platform interior setting. The stratigraphic architectureof this succession mostly consists of vertically stacked tab-ular beds as the result of the continued aggradation ofinner-platform limestones in a subsident area. In situ car-bonate sedimentation was able to Wll the available accom-modation keeping up with the rate of relative sea-level rise.As a result, sedimentation developed constantly in shallow-water environments.

In spite of its relatively simple architecture, the physicalexpression of the studied succession is quite complex sincethe vertical sedimentary signature of lithofacies changed intime and showed a predominant cyclic pattern. At the bedscale, these cycles correspond to small-scale sequences thatstack, at the bedsets scale, into large-scale sequences.

Focusing on large-scale sequences, it is proposedthat transgressive deposits correspond to that package ofsmall-scale sequences showing a deepening-upward trendof lithofacies evolution. Their top is characterized by amaximum-Xooding zone made up of a thin package ofsmall-scale sequences formed by the relatively deepestlithofacies association. Highstand deposits correspond tothat package of small-scale sequences showing a shallow-ing-upward trend of lithofacies evolution. The top of these

deposits is characterized by a sequence-boundary made upof either a thin package of small-scale sequences (sequenceboundary zones), formed by the relatively shallowest lithof-acies association, or by a massive layer of solution-collapsebreccias.

In conclusion, this facies-based approach, applied to therecognition of large-scale depositional sequences in the“mid”-Cretaceous platform interior setting of the ACP,demonstrated that diagnostic intervals for sequence-strati-graphic interpretation are mostly made up of a multi-signa-ture record of small-scale sequences, which are part of apredictable stratigraphic pattern.

The good Wt between large-scale sequences with maintransgressive/regressive cycles published in the sequencechronostratigraphic chart of European basins suggests thatlow-frequency sea-level changes recorded at the regionalscale played an important role in determining thesequence stratigraphic architecture of the studied succes-sion. Nevertheless, it is not excluded that the occurrencein the middle part of the succession of solution-collapsebreccias may be alternatively interpreted as the local sig-nature of the regional-known “mid”-Cretaceous tectonicevent, which exposed the carbonate platform for a timespan long enough to produce deep karstiWcation ofcarbonates.

Acknowledgments I would like to thank M. CaVau for the biostrati-graphic work, M. Tropeano for the critical review of an early draft ofthe text, and P. Pieri for fruitful discussions. I am sincerely grateful toreviewers A. Strasser and D. Sanders who considerably improved themanuscript with many constructive comments and suggestions. I amalso grateful to A. Freiwald for editorial advice. Data and results of thiswork were partly obtained during the geological survey for the realiza-tion of the new 438 Sheet “Bari” (scale 1:50000)—CARG (CARtogra-Wa Geologica)-Puglia Project. Financial support for this research wasprovided by MIUR grants to L. Sabato (ex 60% 2008–2009).

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