The Structure of the Aurunci Mountains (Southern Lazio): a Balanced Cross-Section and Its Restoration

Home , Aurunci, Aurunci Mountains, Campodimele, Monti Ausoni, Monti Lepini

Boll. Soc. Geol. It., Volume speciale n. 1 (2002), 151-159, 7 ff.

The structure of the Aurunci Mountains (southern Lazio): a balanced cross-section and its restoration

DAVID ROSSI (*), SABINA BIGI (**), MARIO DEL CASTELLO (***) & PIO DI MANNA (****)

ABSTRACT sfruttano il line-length balancing methods, sono stati calcolati i tassi di estensione e di raccorciamento, che possono essere generalizzati This short note presents a short balanced cross section between all’intera struttura studiata. Questa presenta una notevole comples- Gaeta and Campodimele, based on field data from a geological- sità strutturale, caratterizzata dalla sovrapposizione delle strutture structural map (1:25.000 scale). distensive, legate all’estensione tirrenica su quelle compressive me- The investigated area presents some specific topics, which dif- dio-mioceniche a vergenza nord-orientale. Nell’area infatti sono ri- ferentiate it from the adjacent northern and southern zones. The conoscibili due unità tettoniche principali, sovrapposte mediante un structural setting is characterized by a thin-skinned thrusting which piano di sovrascorrimento a generale andamento appenninico che involved the whole sedimentary succession (Upper Triassic-Upper presenta una traiettoria tipo ramp-flat-ramp. Nel settore sudocciden- Cretaceous). After the structuring of the Apenninic chain, the Plio- tale dell’area il sovrascorrimento determina la sovrapposizione dei Pleistocene extension offsets this sector along NW and subordinated termini triassico-giurassici su quelli cenomaniani; mentre nel setto- NE trending normal faults. re centrale un piano ausiliario posto alla base del cretacico determi- The Aurunci Mountains belong to the southwestern portion of na soltanto un raddoppio della porzione cretacica della successione. the Lazio-Abruzzi (mesozoic) carbonate platform domain. The sedi- Probabilmente associabili alle fasi finali della deformazione sono in- mentary succession shows the characters of inner shelf environ- fine i sistemi di faglie normali a direzione prevalentemente appen- ment, with facies ranging from subtidal to supratidal. The lithotypes ninica; mentre parte delle strutture distensive minori mostrano di- are mainly laminated dolomitic wackestones and calcareous pack- rezioni antiappenniniche e riattivano in senso normale anche faglie stones with benthic assemblages dominated by molluscs, foraminif- preesistenti a direzione N-S. era and green algae. I calcoli di bilanciamento hanno fornito valori di raccorcia- A number of outcrop of reasonable quality has enabled the con- mento pari a 6.6 km (32.8%) mentre i valori di estensione calcolati struction of one balanced cross-section throughout the Aurunci sono pari a 4.9 km (26.9%). Mountains, using the line-length method. This has been made up using as main detachment the Triassic dolostones levels and, as sec- ERMINI CHIAVE ondary ones, the lower portion of the cretaceous succession. T : Sezione geologico bilanciata, Appennino Using specific computers software we obtain a value of 6.6 km centrale, Monti Ausoni-Aurunci. e.g. (32.8%) of shortening, and a 4.9 km e.g. (26.9%) of extension.

KEY WORDS: Balanced cross-section, central Apennines, 1. INTRODUCTION Aurunci and Ausoni Mountains. Cross-section balancing has been used widely to produce structural models of the external parts of fold and RIASSUNTO thrust belts and is used in both contractional and extensional tectonic regimes. Restoration and balancing is an La struttura dei Monti Aurunci (Lazio meridionale): una se- old method of calculating depth to detachment and short- zione geologico-bilanciata e la sua retrodeformazione. ening (CHAMBERLAIN, 1910; BUCHER, 1933; GOUGEL, I Monti Ausoni-Aurunci costituiscono la parte sudoccidentale 1962) which was modified and adapted by DAHLSTROM del dominio della Piattaforma Laziale-Abruzzese, dove affiora una (1969), HOSSACK (1979); BOYER & ELLIOTT (1982); COO- potente successione carbonatica dal Trias superiore al Cretaceo su- PER (1983); GIBBS (1983); WOODWARD et alii (1985); periore di mare sottile, costituita essenzialmente da calcari fangoso- stenuti, calcari dolomitici e dolomie (ACCORDI et alii, 1988; CARAN- DE PAOR (1987, 1990); DE PAOR et alii (1988) and many NANTE et alii, 1978; CHIOCCHINI et alii, 1994). others. Attraverso una dettagliata analisi di superficie, ottenuta tramite Using the most commonly utilized geometric con- un rilevamento geologico alla scala 1:25.000, ed una analisi struttu- straints for thrust structures, we propose a short balanced rale alla meso ed alla macro-scala, viene proposta una sezione geologica bilanciata tra Gaeta e Campodimele. Utilizzando software che geological cross-section, between Gaeta and Campodi- mele in the Aurunci and Ausoni Mountains (southern Lazio). Data come from field mapping and conventional structural analysis. We use the line-length balancing (*) Dottorato di Ricerca in Scienze della Terra, Università method (DENNISON & WOODWARD, 1963) to calculate the degli Studi di Roma «La Sapienza» (P.le A. Moro, 5 – Roma), E-mail: shortening and extension of the section. [email protected] (**) Dipartimento di Scienze della Terra Università degli Stu- di di Roma «La Sapienza» (P.le A. Moro, 5 – Roma), E-mail: [email protected] 2. REGIONAL SETTING (***) Dottorato di Ricerca in Scienze della Terra Università degli Studi di Bologna (Via Zamboni, 67 – 40129 Bologna), E-mail: The Aurunci and Ausoni Mountains, in Southern [email protected] (****) Collaboratore esterno al Dipartimento di Scienze della Lazio area, represents the most internal part of the Lazio- Terra Università degli Studi di Roma «La Sapienza» (Via Farneti Abruzzi carbonate paleo-platform sensu CHIOCCHINI & S. Giorgio, 17 – 03020 Pico FR). MANCINELLI (1977). This area is comprised among the 152 D. ROSSI ET ALII

Fig. 1 - Structural scheme of Souther Latium: 1) Quaternary deposits; 2) Plio-Pleistocene vul- canic sediments; 3) Miocene silicoclastic sequences; 4) Argille Varicolori formation; 5) Lazio- Abruzzi carbonate platform deposits; 6) Upper Triassic outcropping formations; 7) Thrust faults; 8) Normal faults; 9) minor faults. – Schema strutturale del Lazio meridionale: 1) Depositi quater- nari; 2) Sedimenti vulcanici Plio-Pleistocenici; 3) Sequenze silicoclastiche mioceniche; 4) For- mazione delle Argille varicolori; 5) Depositi di piattaforma Lazia- le-Abruzzese; 6) Affioramenti del Triassico superiore; 7) Faglie in- verse; 8) Faglie normali; 9) Faglie di minore importanza.

Amaseno River in the West, the Latina Valley in the 3. STRATIGRAPHICAL DATA North, the Garigliano River in the East and the Tyrrhen- ian Sea in the South (fig. 1). The sedimentary succession The bottom of the sedimentary succession cropping cropping out in the whole area belongs to the carbonate out in the area consists of massive dolomites covered by platform domain. It consists of neritic carbonate deposits limestone beds from Upper Triassic to Lower LIASSIC of Upper Triassic to Upper Cretaceous age (ACCORDI et (fig. 2) (CHIOCCHINI & MANCINELLI, 1977; CARANNANTE alii, 1988; CARANNANTE et alii, 1978; CARBONE, 1992; CA- et alii, 1978). Above this sabkha deposits, marine lagunal TENACCI, 1978; CHIOCCHINI & MANCINELLI, 1977; CHIOC- subtidal limestones (Middle Liassic-Upper Jurassic), CHINI et alii, 1984; DE CASTRO, 1962; GROSSI, 1933; PRA- rarely and poorly dolomitized occur. The facies analyses TURLON, 1964). Such sequences are typical of subsiding suggests the development of a carbonate inner shelf, carbonate platform areas where the accumulation rate characterised by moderate but variable water energy. counterbalances the relative sea level changes and causes The presence of layers containing rudstones and oolitic fluctuations from supratidal to shallow subtidal environ- deposits suggests the occurrence of depositional environment (ACCORDI et alii, 1988; CARANNANTE et alii, 1978; ment characterised by high energy. The Lower Creta- CHIOCCHINI et alii, 1994). ceous deposits suggests the onset of a carbonate plat- From South to North the structural setting consists of form depositional system ranging from tidal flat to a deformed fold belt, trending NW-SE and bounded to lagoon. The analysis of textural parameters and vertical N-E by a main thrust fault (ACCORDI, 1963, 1964, 1966; organisation of the lithofacies assemblages allow to rec- CASSETTI, 1896; CASSETTI, 1900; CIPOLLARI & COSENTINO, ognise a cyclic organisation of the facies, arranged in 1991, 1995; FRANCHI, 1924). It placed the meso-cenozoic shoaling upward sequences. In the lower part, the sedimentary succession over the upper Miocene terrige- sequence is composed of interbedded wackestones and nous deposits cropping out in the Latina Valley, as men- packstones, sometimes dolomitized. The middle part tioned by many authors (ACOCELLA et alii, 1996; BENEO, (Lower Aptian-Cenomanian) is mainly composed of 1942; CARRARA et alii, 1995; DI FILIPPO, 1978; DI FILIPPO wackestones with interbedded micrites and laminated et alii, 1979; DI FILIPPO & TORO, 1980; DI FILIPPO et alii, dolomicrites. Interformational conglomerates, often dol- 1986; BARTOLE, 1984; MOSTARDINI & MERLINI, 1989). omitized, and discontinuous red layers (paleosoils) are The main tectonic transport is northeastward; in contrast interbedded and suggest the occurrence of depositional the amount of slip determined is not well defined environment characterised by restricted water circula- (PAROTTO, 1980; PATACCA et alii, 1990; TOZZI & CAPO- tion or short emersions. The bioclastic limestones (crys- TORTI, 1991; CERISOLA & MONTONE, 1992; NASO & TAL- talline limestone) occurring in the upper Cenomanian LINI, 1993; CIPOLLARI & COSENTINO, 1995; CIPOLLARI et carbonate succession are indicative of deposition process alii, 1995). A Plio-Pleistocene normal faults systems offset controlled by very high hidrodynamism. The sedimen- to the south-west the whole structure (PAROTTO & PRA- tary succession shows an increase of the occurrence of TURLON, 1975). open shelf facies in the Upper Cretaceous; during this THE STRUCTURE OF THE AURUNCI MOUNTAINS 153

Fig. 2 - Stratigraphic column of the outcropping formations. – Colonna stratigrafica delle formazioni affioranti. 154 D. ROSSI ET ALII

Fig. 3 - Structural scheme of the study area. U1) Hangingwall unit; U2) intermediate unit; U3) footwall unit. The tick black line represent the cross section trace. – Schema strutturale dell’area di studio. U1) Unita di tetto; U2) Unita intermedia; U3) Unita di letto.

period the reef environment (Caprinid, Coral rudstones, 4. STRUCTURAL SETTING ALONG THE GAETA Ippuritid banks, Orbitoid shoals) moved toward inner AND CAMPODIMELE BALANCED CROSS-SECTION platform areas. As a consequence, no organogenic rims but lense-shaped bodies of bioclastic sediments seem to The Gaeta and Campodimele cross-section crosses the characterise this carbonate platform. Rudist floatstones Aurunci Mountains area along a SSW-NNE direction, are organised in subtidal cycles with bioclastic material, parallel to the main tectonic transport direction (fig. 3). produced essentially by bioerosive processes acting on In this sector of the Aurunci Mountains, two main tecton- the rudist mound and by resedimentation processes. This ics unit can be recognized, superimposed one on the sedimentary succession generally stops in the studied other by a main thrust planes trending mainly NW-SE area at the end of the Cretaceous; nevertheless, in the with a N25°E main tectonic transport as shown in fig. 3. eastern sector of the Aurunci Mountains, includes sedi- In the south-western part of the sector the thrust ments which extend up to Miocene. These limestones, plane places the Triassic-Jurassic limestones of the han- represented by the Formation known in the literature as gingwall on the Cenomanian bioclastic limestones of the «Calcari a Briozoi e Litotamni» of Burdigalian-Serraval- footwall in the southwestern sector. The entire structure lian age, overlies the Cretaceous platform sediments by shows a north-eastward vergence. The same thrust gives a paraconformity surface. Locally the top of the descri- rise to the contact between the lower and upper Creta- bed succession is also covered by the chaotic «Argille ceous portions of the succession in the norther part of the varicolori Formation» during Oligocene-Aquitanian age area. The main detachment level is represented by the (PAROTTO, 1980; PAROTTO, 1996), that covers in uncon- Triassic dolostones; a minor detachment level in the formity the whole carbonate substratum. The geometric Lower Certaceous limestons has been localized. relationship between these deposits and the structural More in detail, along the cross-section (fig. 3), three setting of the area still not clear; some evidences suggest main sectors can be recognized, showing different geomet- the presence of a deformed and uplift substratum dur- ric arrangement. In the south-eastern side the hangingwall ing the onset of the «Argille Varicolori Formation». Fur- ramp, with 60/250° dip angle, is well developed, and the thermore these formation should be deformed also dur- hangingwall anticline can be reconstructed as well with ing others upper Tortonian-Messinian tectonic events 20/340° hinge direction. The thrust plane is also offset by (ANGELUCCI et alii, 1963; ACCORDI et alii, 1967). tear faults, which can be traced with a direction ranging THE STRUCTURE OF THE AURUNCI MOUNTAINS 155

Fig. 4 - Detailed structural scheme of the intermediate unit (M.te Grande-M.te Larigno). The stereonet in the box represent the lower hemisphere projection of the Schmidt’ Net. The black triangle represent fold hinge direction, the black dots represent the pole of fault plane; the cross line represent pole of bedding, while the X-shaped lines represent the pole of joints. – Schema strutturale di dettaglio dell’unita tettonica intermedia (M.te Grande-M.te Larigno). Le proiezioni sull’emisfero inferiore del reticolo di Schmidt’ sono inserite nel riquadro in basso. I triangolini neri rappresentano le linee di cerniera delle mesopieghe; i pallini neri si riferiscono ai poli dei piani di faglia; le crocette si riferiscono ai poli dei piani di stratificazione; le ics si riferiscono ai poli dei piani delle fratture associate. 156 D. ROSSI ET ALII

cline, essentially returns stratigraphy back to its unde- formed regional level. Furthermore the anticline-sincline described above are refolded by a second hinge direction generations NW-SE («D» bedding stereonet; fig. 4). The geometric relationship between the thrust planes and the folds suggests the occurrence of two steps in the deformation process, the first one (anticline and syncline with ESE-WNW hinge direction) characterized by the detachment of the upper part of the succession and the development of the first folds generation (buckling process described above), the second produced by the super- position of non-coaxial upright fold set (NE-SW hinge direction) upon the first-phase fold pattern due to a second compressional phase. In the Northeastern portion of the cross-section the footwall crops out, showing a gently folded and/or horizontal setting (fig. 3). Normal faults system, trending Fig. 5 - The photo show a compressive S-C fabric superimposed by pure shear extensional conjugate systems X-X’, cropping out along NW-SE linked to the Tyrrhenian extensional process the eastern slope of M. Grande-M.te Larigno unit. – La foto mostra un fabric S-C compressivo, al quale è sovraimposto un sistema coniugato estensionale X-X’, affiorante lungo il versante orientale dell’unità strutturale M.te Grande-M.te Larigno. between N15-40°E well exposed along the NW-SE Itri valley (fig. 3). In the central sector, the thrust trace shows an intermediate flat developed in the lower Cretaceous terms which shows a complex geometry characterized by the development of folds and minor splays. The Cretaceous sedimentary succession cropping out between these thrust planes is mainly characterized by several buckling folds, detached at the base of the Lower Cretaceous, with ESE- WNW main hinge direction (fig. 3). A quantitative analyses carried out (using diffractometrical analyses) on many col- lected samples along the main buckling detachment levels, shows a predominance of dolomite 98% with only 2% of calcite. Furthermore the presence of microfratures inside these rocks cropping out at the base of the cretaceous sediments, give rise for the buckling processes that developed along these dolomite levels. The development of a intermediate detachment level at the bottom of the Lower Creta- ceous described above is likely due to the high pore pressure developed in these rocks supported by the presence of impermeable levels at the top of the lower Cretaceous (Orbitoline Marls, Albiano p.p.- Cenomanian p.p.). During the diagenesis process the occurrence of this level and many others, prevented the expulsion of water and the per- manence of fluids inside the Lower Cretaceous dolomites and limestone. The lithostatic load before and the tectonic stress after that acted on these rocks increase the fluid pressure that reach the lithostatic value. A detailed structural analysis along the main thrust faults has revealed a compressive S-C fabric, superimposed by pure shear extensional conjugate system (X-X’ in CALAMITA, 1991) (fig. 5). This structural setting is evi- dent along the eastern slope of M. Grande-M. Larigno unit, where the main thrust plane crops out. More in detail the M. Grande-M. Larigno structure (fig. 4) consist of a anticline and syncline system (WNW-ESE hinge direction) linked to a secondary thrust plane developed in the hangingwall of the main thrust. The detailed geome- Fig. 6 - Example of restore procedure with inversion regime along try of the forelimb of the M. Grande anticline contains the central sector of the Gaeta-Campodimele cross section. The trace of the section is shown in fig. 4. maximum bedding dips ranging from 30° to strongly – Esempio di retrodeformazione in regime di inversione tettonica lungo overturned in the other part of the anticline. A frontal un settore della sezione geologica Gaeta-Campodimele. La traccia di syncline (M. Larigno), in the north of the M. Grande anti- questa sezione è mostrata in fig. 4. THE STRUCTURE OF THE AURUNCI MOUNTAINS 157

Fig. 7 - Balanced cross-section procedure: a) Geological cross-section between Gaeta and Campodimele. b) Restored section before the extensional phase. c) Restored section before the second compressional phase. d) Resto- red section before the first compressional phase. Equations: E) extension; R) shortening; La) pin line distance of the cross section; Lb) pin line distance before extension; Le) pin line distance after compression; Lc) pin line distance before compression; Rb%) percentage of shortening of the first compressional phase; Rt%) percentage of shortening of the second compressional phase. – La sezione geologica è stata retrodefor- mata come segue: a) Sezione geologica tra Gaeta e Campodimele; b) Retrodefor- mazione alla fase pre-tettonica distensiva; c) Retrodeformazione alla seconda fase compressiva; d) Retrodeformazione alla prima fase compressiva. Equazioni: E) Estensione; R) Raccorciamento; La) Distanza esistente tra i punti di riferimento nella sezione geologica; Lb) Di- stanza esistente tra i punti di riferimen- to dopo la retrodeformazione alla fase pre-tettonica distensiva; Le) Distanza tra i punti di riferimento misurata prima della retrodeformazione alla fase pre- tettonica compressiva; Lc) Distanza tra i punti di riferimento dopo la retrodeformazione alla fase pre-tettonica compressiva; Rb%) Percentuale del raccorciamento parziale riferita alla prima fase compressiva; Rt%) Percentuale del raccorciamento parziale riferita alla seconda fase compressiva.

(Plio-Pleistocene to Olocene) cut the thrust belt with off- tion can be assumed through all the section, and that the set of about 400-700 m. Southwestern dipping normal thickness of the sedimentary succession doesn’t change faults locally reactivate pre-existing thrust faults, espe- during the deformation process (DAHLSTROM, 1969; cially along the M.te Grande-M.te Larigno unit, where it WICKHAM & MOECKEL, 1997; WOODWARD et alii, 1989; has also been recognized an extensional reactivation of SUPPE, 1983; ELLIOT, 1983; MOSTARDINI & MERLINI, the pre-existing thrust faults. These processes produce a 1986; BALLY et alii, 1986). This has been made up using falsify offset value of the thrust faults as shown in fig. 6. two main detachment levels: one in the Triassic dolostone, and the other at the bottom of the Lower Creta- ceous dolostone. The line of the section was drown per- 5. THE GAETA AND CAMPODIMELE BALANCED pendicular to the major thrusts, large order fold trends CROSS-SECTION associated with thrust ramp. Small-scale folds were not used to determine the transport direction, especially in The balance of the section has been made using the areas of high strain adjacent to faults. Balancing a section line-length method, considering that plain strain condi- requires a comparison between two sections: a deformed 158 D. ROSSI ET ALII state one, and a restored one. The «balancing» means that 4) The structural analyses allow us to choose a respective quantities (lengths or areas) in each section N30°E compressional slip direction. These give rise for should be equal. The development of the balanced section the orientation of the cross section that was constructed using a computer software program was traced as in the parallel to the tectonic transport direction; following steps: 5) The restoration value obtained for the balanced 1) we compiled geologic maps and subsurface data; cross-section are 6.6 km of shortening (i.e. 32.8%) and 4.9 2) we drew a section line parallel to the direction of km of extension (i.e. 26.9%). tectonic transport obtained by macro and meso-structu- These results, shows that the Ausoni-Aurunci com- ral analyses; pressional system was strongly driven by different strati- 3) we drew a separate restored stratigraphic layer- graphic behaviour, due to two main thick dolomite levels cake using the youngest pre-orogenic unit as a horizontal (Triassic and Lower Cretaceous). The Lower Cretaceous reference and, using thickness data from surface and sub- one prevents the development of buckling folds struc- surface measurements for each thrust sheet; tures that characterized the hangingwall of the main 4) we drew a foreland pin line in the deformed sec- thrust. tion to correspond to the foreland edge of the restored one; 5) we gave the same hanging wall cut-off to the offset formations, as measured in field or as reconstructed ACKNOWLEDGEMENTS by unfolding processes; The authors acknowledge Prof. E. Centamore for helpful and 6) we measured bed lengths from the foreland pin critical comments on this work, Stefano Stellino and Piero Patarelli point back through the section for each horizon; for laboratory analyses and interpretation. We acknowledge also 7) we measured off the same bed lengths from the Valeria Misiti. foreland margin of the restored stratigraphic wedge. This locates all faults in the restored section; 8) we check that all local pin lines, or well-constrained REFERENCES surface geometries are preserved in the restored section; 9) we check that respective hangingwall and foot- ACCORDI G., ANGELUCCI A. & SIRNA G. (1967) - Note Illustrative del- wall cut-off angles correspond. No gaps or overlaps in the la carta geologica d’Italia F. 159/160 Frosinone-Cassino. restored section are permitted. ACCORDI G., CARBONE F., CIVITELLI G., CORDA L., DE RITA D., ESU D., FUNICELLO R., KOTSAKIS T., MARIOTTI G. & SPOSATO A. 10) For inversion tectonic processes we restore, along (1988) - Note illustrative della carta delle litofacies del Lazio- the same fault plane, first of all the offset of normal Abruzzo ed aree limitrofe. C.N.R.-P.F. Geodinamica: sottoproget- faults; using the same fault plane we restored the offset to 4, «Quaderni della Ricerca Scientifica», 114 (5), 223 pp. of thrust faults, as shown in the examples of fig. 6. ANGELUCCI A., DEVOTO G. & FARINACCI A. (1963) - Le argille caoti- che di Colle Cavallaro a Est di Castro dei Volsci, Frosinone. Geo- The restored section before the extensional phase and logica Romana, 2, 305-329. the compressional ones are shown respectively in (figs. 7a BALLY A.W., BURBI L., COOPER C. & GHELARDONI R. (1986) - Bal- and 7d). In the balanced geological section between Gaeta anced section and seismic reflection profiles acros the central and Campodimele the whole structure shows shortening Apennines. Mem. Soc. Geol. It., 35, 257-310. value of 6.6 km (about 32.8%). The restoration allow also BARTOLE R. (1984) - Tectonic structure of the Latian-Campain shelf to calculate the extension value of 4.9 km (about 26.9%). (Tyrrenian sea). Boll. Ocean. Teor. Appl., 2 (3), 197-230. The balanced value obtained are compatible with the BOYER S.E. & ELLIOT D. (1982) - Thrust systems. A.A.P.G. Bullettin, 66, 1196-1230. ones calculated by other authors in adjacent areas (BALLY et alii, 1986). BUCHER W.H. (1933) - The deformation of the Earth’s Crust. Prince- ton University Press, Princeton, New Jersey. CALAMITA F. (1991) - Extensional mesostructures in thrust shear zones: example from the Umbria-Marchean Apennine. Boll. Soc. 6. CONCLUSION Geol. It., 110, 469-480. CARANNANTE G., CARBONE F., CATENACCI V. & SIMONE L. (1978) - I The results of our field and analytical investigation carbonati triassici dei Monti Aurunci: facies deposizionali e dia- allow us to reconstruct the tectonic setting of the area genetiche. Boll. Soc. Geol. It., 97, 687-698. and its deformation history. The most important results CARBONE F. (1992) - Cretaceous depositional system of the evolving can be resume as follows: mesozoic carbonate platform of central apennine thrust belt, Italy. Geologica Romana, 29, 31-53. 1) The sedimentary succession cropping out in the CARRARA C., FREZZOTTI M. & GIRAUDI C. (1995) - Area compresa tra whole area consist of neritic carbonate deposits from la Valle Latina e la Valle Roveto: stratigrafia plio-quaternaria. upper Triassic to upper Cretaceous, with two main Enea Serie Studi e Ricerche Lazio meridionale. detachment levels, one on the top of Triassic massive dol- CASSETTI M. (1896) - Sulla costruzione geologica dei Monti di Gaeta. omites, a second one localized in the Lower Cretaceous Boll. R. Commit. Geol. It., 27, 36-45. dolomites; CASSETTI M. (1900) - Nuove osservazioni geologiche sui monti di Gae- 2) The whole studied area is characterized by two ta. Boll. R. Commit. Geol. It., 31, 74-180. main tectonics unit, an upper and a lower ones, superim- CATENACCI V. (1976) - Environmental analogies between on upper posed one on the other by main thrust plane trending cenomanian «Bivalve» facies of the Lepini Mts. (Latium) and the NW-SE with a north-eastward vergence; lower Jurassic «Litjiotis» facies. Boll. Soc. Geol. It., 95, 875-880. 3) Two different generation of fold sets is developed CATENACCI V. (1978) - I depositi bioclastici saccaroidi della sequenza medio cretacica dei M.ti Lepini. Caratteri sedimentologici e consi- during the compressional phases in the upper unit. The derazioni generiche. Boll. Soc. Geol. It., 95, 851-873. refolded folds (ESE-WNW and NE-SW), cropping out CERISOLA R. & MONTONE P. (1992) - Analisi strutturale di un setto- along the M. Grande-M. Larigno structure, represent two re della catena dei Monti Ausoni-Aurunci (Lazio, Italia centrale). non coaxial folds pattern; Boll. Soc. Geol. It., 111, 449-457. THE STRUCTURE OF THE AURUNCI MOUNTAINS 159

CHIOCCHINI M., FARINACCI A., MANCINELLI A., MOLINARI V. & PO- ELLIOT D. (1983) - The costruction of balanced cross sections. Jour- TETTI M. (1994) - Biostratigrafia a foraminiferi, dasidacladali e nal of Structural Geology, 5, 101. calpionelle delle successioni carbonatiche mesozoiche dell’Appen- FRANCHI S. (1924) - Il grande slittamento delle masse calcaree secon- nino centrale. Studi Geologici Camerti, Vol. Spec. 1994, A, 9- darie dei monti ausoni e lepini sui terreni miocenici della Valle del 130. Liri e della Valle Latina. Rend. R. Acc. Naz. Lincei, 33, 60-66. CHAMBERLAIN R.T. (1910) - The Appalachian folds of central Pennsyl- GIBBS A.D. (1983) - Balanced cross-section construction from seismic vania. Journal of Geology, 18, 228-251. sections in areas of extensional tectonics. Journal of Structural CHIOCCHINI M. & MANCINELLI A. (1977) - Microbiostratigrafia del Geology, 5, 153-160. mesozoico in facies di piattaforma carbonatica dei Monti Aurun- GOUGEL J. (1962) - Tectonics. W.H. Freeman, San Francisco. ci (Lazio meridionale). Studi Geol. Camerti, 3, 109-152. GROSSI M. (1933) - Note illustrative della Carta Geologica d’Italia, Fo- CHIOCCHINI M., MANCINELLI A. & ROMANO A. (1984) - Stratigraphic glio Frosinone. R. Uff. Geol. d’Italia. distribution of benthic foraminifera in the Aptian, Albian and HOSSACK J.R. (1979) - The use of balanced cross-sections in the cal- Cenomanian carbonate sequences of the Aurunci and Ausoni culations of orogenic contractions. Journal of the Geological mountains (Southern Latium, Italy). Benthos, 83, 167-181. Society of London, 136, 705-711. CIPOLLARI P. & COSENTINO D. (1991) - Considerazioni sulla struttu- MOSTARDINI F. & MERLINI S. (1986) - Appennino centro meridiona- razione della catena dei Monti Aurunci: vincoli stratigrafici. Stu- le: sezione geologica e proposta di un modello strutturale. Mem. di Geol. Camerti, Vol. Spec. (1991-2), CROP 11, 151-156. Soc. Geol. It., 35, 177-202. IPOLLARI OSENTINO C P. & C D. (1995) - Il sistema Tirreno-Appennino: NASO G. & TALLINI M. (1993) - Tettonica compressiva e distensiva dei segmentazione litosferica e propagazione del fronte compressivo. Monti Aurunci occidentali (Appennino centrale): prime conside- Studi Geologici Camerti, Geodinamica e tettonica attiva del Si- razioni. Geologica Romana, 29, 455-462. stema Tirreno-Appennino, Volume Speciale 1995/2, 125-134. PAROTTO M. (1980) - Apennin central. In: introduction a la geologie CIPOLLARI P., COSENTINO D. & PAROTTO M. (1995) - Modello cine- generale d’Italie. 26° Congr. Geol. Intern., Parigi 1980, 33-37. matico-strutturale dell’Italia centrale. Studi Geologici Camerti, PAROTTO M. (1996) - Mineralogia delle argille varicolori dell’Appenni- Volume Speciale 1995/2, 135-143. no centrale: risultati preliminari e prospettive di ricerca. Boll. Soc. COOPER M.A. (1983) - The calculation of bulk strain in oblique and Geol. It., 115, 698-700. inclined balanced sections. Journal of Structural Geology, 5, 161- PAROTTO M. & PRATURLON A. (1975) - Geological summary of the 165. central Apennines, in: «Structural model of Italy». Quad. Ric. DAHLSTROM C.D.A. (1969) - Balanced cross sections. Canadian Jour- Scientifica, C.N.R., 90, 257-300. nal of Earth Sciences, 6, 743-757. PATACCA E., SARTORI R. & SCANDONE P. (1990) - Tyrrenian basin and DE CASTRO P. (1962) - Sulla presenza del Giura (Dogger-Malm) nei apenninic arcs: Kinematic relations since Tortonian times. Mem. monti Aurunci. Bol. Soc. Nat. di Napoli, 71. Soc. Geol. It., 45, 435-451. DENNISON J.M. & WOODWARD H.P. (1963) - Palinspastic maps of PRATURLON A. (1964) - Calcareous algae from Jurassic-Cretaceous central Appalachians. A.A.P.G. Bullettin, 47, 666-680. limestones of central Apennine (southern Latium-Abruzzi). Geol. DE PAOR D.G. (1987) - Stretch in shear zones: implications for section Romana, 3, 171-202. balancing. Journal of Structural Geology, 9, 893-895. ROYSE F.J., WARNER M.A. & REESE D.L. (1975) - Thrust belt struc- DE PAOR D.G. (1990) - Cross-section balancing in space and time. In tural geometry and relatd stratigraphic problems, Wyoming-Idaho- Petroleum and Tectonics in Mobil Belts. Ed. J. Letouzey, editions Northern Utah. In Rocky Mountain Association of Geologist, Technip, Paris, 149-154. Symposium on Deep Drilling Frontiers in central Rocky Moun- DE PAOR D.G. & BRADLEY D.C. (1988) - Balanced sections in thrust tains, 4-54. belts, Part 2: computerized line and area balancing. Geobyte, 3(5), SUPPE J. (1983) - Geometry and kinematics of fault-bend folding. 33-37. American Journal of Science, 183, 684-721. DI FILIPPO M. (1978) - Profili gravimetrici e modello bidimensionale TOZZI M. & CAPOTORTI F. (1991) - Tettonica trascorrente nella peni- dei Monti Lepini. Rend. Soc. Geol. It., 1, 49-52. sola Sorrentina. Mem. Soc. Geol. It., 47, 235-249. DI FILIPPO M., FAVALLI P., SCALERA S.G. & TORO B. (1986) - Lazio: WOODWARD N.B., BOYER S.E. & SUPPE J. (1985) - An outline of bal- studio delle strutture tettoniche profonde e superficiali mediante il anced Cross-sections. University of Tennesse, Studies in Geo- confronto di dati gravimetrici e sismologici. Mem. Soc. Geol. It., logy, 11. 35, 294-302. WOODWARD N.B., BOYER S.E. & SUPPE J. (1989) - Balanced geologi- DI FILIPPO M., FUNICIELLO R. & SERVA L. (1979) - Il margine tirre- cal cross-sections: An essential technique in Geological research nico dell’Italia centrale in un profilo M. Amiata-S. Felice Circeo. and exploration. Short course presented at the 28th International Rend. Soc. Geol. It., 2, 43-46. Geological Congress Washington D. C., Vol. 6, 131 p.p. DI FILIPPO M. & TORO B. (1980) - Analisi gravimetrica delle struttu- WICKHAM J. & MOECKEL G. (1997) - Restoration of structural cross- re del Lazio meridionale. Geologica Romana, 19, 285-294. sections. Journal of Structural Seology, 19 (7), 975-986.

Manoscritto pervenuto il 23 Agosto 2000; testo approvato per la stampa il 29 Maggio 2001; ultime bozze restituite l’8 Ottobre 2001.

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