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Le tecniche geofisiche sono i metodi più efficienti per ottenere informazioni sulle strutture presenti nel sottosuolo. Ad oggi, la tomografia di resistività elettrica (ERT) è il metodo più utilizzato per il rilevamento di vuoti sotterranei, tuttavia, la combinazione con dati derivanti da diversi metodi geofisici è l’approccio più adatto per la determinazione delle cavità. Negli ultimi anni, la ERT è stata sempre più spesso congiunta alla tomografia sismica a rifrazione (SRT) al fine di ottenere interpretazioni più robuste anche utilizzando un approccio di tipo statistico. La cluster analysis eseguita su unità statistiche definite da valori di resistività elettrica, velocità delle onde P e densità sismica, ha permesso di ottenere interpretazioni ottimali delle strutture del sottosuolo. In base al numero di cluster, le mappe di distribuzione sono state costruite in uno spazio multiparametrico, consentendo di definire determinati limiti di variabilità per i parametri selezionati. Geophysical techniques are the most efficient methods for obtaining information on the structures present in the subsoil. Today electrical resistivity tomography (ERT) is the most used method for the detection of underground voids, however, the combination of experimental data from different geophysical methods is the most suitable approach for the determination of cavities. In recent years, the ERT has been joined more and more often to the technique of seismic refraction tomography (SRT) in order to obtain more robust interpretations also using a clustering approach. The cluster analysis performed on static units defined by electrical resistivity values, P wave velocities, and seismic density on coincident sections, allowed to interpret the subsoil structures. Based on the number of clusters, cluster distribution maps have been constructed in the multi-parameter space, allowing to define certain variability limits for the selected parameters.

In the past 15 years several expeditions by French, American and especially Italian cavers have surveyed over 15 km of salt cave passages in the Cordillera de la Sal, close to San Pedro de Atacama village (Atacama Desert, Northern Chile). Over 50 caves have been explored up to now at an elevation around 2,500 m asl. These karst systems are characterized by in-cave temperature of around 17 °C and a relative humidity always very low, with a maximum of 15%. This extreme aridity is due to the severe conditions of the area with only a couple millimeters annual rainfall and several years without rain. Currently the rare precipitation events are enough to allow the dissolution of the salt rock and crusts, and the deepening of underground meandering river passages. Moreover, after the sporadic rain events, the water penetrating the cave’s host rock along fractures and bedding plains leads to the dissolution of primary minerals and allows the formation of seeping brines with dissolved salts. Both these processes selectively add solutes to the incoming undersaturated rainwater. The evaporation of these resulting salt-rich fluids at the cave atmosphere interface causes secondary minerals to precipitate. Mineral samples have been collected in eight caves, and include stalactites, flowstones, precipitates that form crusts in the streambeds and at the groundwater seeps, parietal coatings, earthy masses from the cave floors and efflorescence salts on ceiling rock outcrops. Most secondary deposits are composed of halite, but also other halides, carbonates, sulphates, nitrates, phosphates, and silicates have been discovered. Among the sixteen observed minerals, antarcticite, leonite, darapskite, blödite, atacamite and anhydrite are worth mentioning. The peculiar climate (extremely arid) and the very special environment dominated by NaCl and CaSO4, allow the crystallization primarily of halite. Atacamite was found where local enrichment in Cu (of hydrothermal origin) occurs, and antarcticite precipitates by the final evaporation of SO4-depleted brine (after early precipitation of anhydrite). Among sulphates, the metals necessary for the formation of these mineral species (magnesium, potassium, sulphate) derive from the cave sediments while nitrates are supplied by bird guano. Salt mineral precipitation is controlled by the temperature dependence solubility of the species in saline water, so that different secondary minerals were observed.

As part of activities of the “Inside the Glaciers” project, managed by an Italian team of speleologists and geologists with the purpose of studying several ice-caves in Europe and South America, a research campaign was recently carried out in Mount Etna (Sicily, Italy). This volcano is the highest active in Europe and hosts more than 200 caves including Grotta del Gelo (Ice Cave) which is located on the Northern flank of Mount Etna at an altitude of about 2040 m a.s.l. This cave was formed during the Etna’s long and most destructive eruption dated from 1614 to 1624 and is one of the most famous because it hosts a small glacier, maybe the southernmost of the Northern hemisphere. Aim of this project was to realize a detailed survey of Grotta del Gelo using a Leica HDS 7000 terrestrial laser scanner in order to acquire precise data measurements of the ice deposits. This survey was the first step of a monitoring project that will be developed in the next years in collaboration with the Etna Regional Park, the Sicilian Regional Speleological Federation and the Centro Speleologico Etneo of Catania which by many years are involved in the topographic monitoring of this particular cave. The proposed article introduces the methods used for this first laser scanning survey campaign of Grotta del Gelo and the results obtained.

Italy is a country hosting a large number of hypogenic sulfuric acid (SAS) speleogenesis caves, mostly located along the Apennine chain, but also in Campania (along the coastline of Capo Palinuro), Apulia (along the coastline of Santa Cesarea Terme) and Sicily. Besides the typical morphologies related to their special geochemical origin (cupolas, replacement pockets, bubble trails, etc), these caves often host abundant secondary mineral deposits, mainly gypsum, being the result of the interaction between the sulfuric acid and the carbonate host rock. Native sulfur deposits are also well visible on the ceiling and roof, and peculiar sulfuric acid minerals such as jarosite, alunite, and other sulfates like copiapite, pickeringite, tschermigite, tamarugite (probably related to the weathering of native clay minerals) have been found in those caves. The presence of typical SAS minerals, together with the morphologies, testifies the influence of rising acidic waters, that likely interact with the deep-seated Triassic evaporite deposits (along the Apennine chain), with volcanic sources or hydrothermal springs in the Tyrrhenian sea (in Campania) and with marine waters that infiltrate on the sea bottom and rise through deep faults (in Apulia). This paper describes the secondary minerals discovered in several caves, and discusses their origin and possible use in reconstructing the evolution of these cave systems.

The little known impact of bats and bat guano in the late stages of cave morphogenesis. Bats are considered as symbolic caves inhabitants. The colonies, sometimes huge, may occupy caves through long periods. Large guano deposits were accumulated. Some have been mined for phosphates, either by hand or at the industrial scale. Bats impact is triple: breathing releases CO 2 , urine is corrosive, and guano mineralization releases acids (carbonic, nitric, sulfuric, and phosphoric). Such aggressive compounds have an effect on carbonate rock and flowstones, either by direct ground corrosion at the contact of the guano, or by condensation-corrosion on walls and ceilings. The speleogenetic impact of these late stages of cave evolution is considerable and may provoke denudation of several meters of rock. The long lasting presence of bat colonies is a major factor of the late speleogenetical stages, making specific morphologies, significant phosphate deposits, and wall reworking ranging from some centimeters to several meters. These corrosion morphologies, sometimes misinterpreted as marks of flooding, are also responsible of the destruction of many prehistoric realizations, which have been preserved only in specific conditions., L'impact méconnu des chauves-souris et du guano dans l'évolution morphologique tardive des cavernes : Les chauves-souris sont considérées comme des occupants emblématiques des grottes. Les colonies, parfois de taille gigantesque, peuvent occuper les cavernes sur de très longues périodes. Ainsi, il se constitue des accumulations de guano dont le volume a favorisé l'exploitation des phosphates, à l'échelle artisanale voire industrielle. L'impact des chauves-souris est triple : leur respiration dégage du CO 2 , leur urine est corrosive, et la minéralisation du guano libère des acides (carbonique, nitrique, sulfurique, phosphorique). Ces substances agressives agissent sur la roche et les concrétions carbonatées, soit par corrosion directe du sol encaissant au contact du guano, soit par condensation-corrosion sur les parois et les plafonds. Bien que tardif dans l'histoire des cavités, l'impact spéléogénétique sur les parois est considérable et peut aller jusqu'à l'ablation de plusieurs mètres d'épaisseur de roche. La présence durable de colonies de chauves-souris est un facteur majeur de spéléogenèse tardive des cavernes, générant des morphologies spécifiques, des dépôts de phosphates conséquents, et un remaniement des parois allant d'un simple rabotage centimétrique jusqu'à des ablations métriques. Ces morphologies de corrosion, qui ont pu être confondues avec des ennoyages, sont probablement responsables de la disparition d'une bonne partie des oeuvres pariétales préhistoriques qui n'ont pu être préservées que dans des conditions bien spécifiques.

International audience; The little known impact of bats and bat guano in the late stages of cave morphogenesis. Bats are considered as symbolic caves inhabitants. The colonies, sometimes huge, may occupy caves through long periods. Large guano deposits were accumulated. Some have been mined for phosphates, either by hand or at the industrial scale. Bats impact is triple: breathing releases CO 2 , urine is corrosive, and guano mineralization releases acids (carbonic, nitric, sulfuric, and phosphoric). Such aggressive compounds have an effect on carbonate rock and flowstones, either by direct ground corrosion at the contact of the guano, or by condensation-corrosion on walls and ceilings. The speleogenetic impact of these late stages of cave evolution is considerable and may provoke denudation of several meters of rock. The long lasting presence of bat colonies is a major factor of the late speleogenetical stages, making specific morphologies, significant phosphate deposits, and wall reworking ranging from some centimeters to several meters. These corrosion morphologies, sometimes misinterpreted as marks of flooding, are also responsible of the destruction of many prehistoric realizations, which have been preserved only in specific conditions.; L'impact méconnu des chauves-souris et du guano dans l'évolution morphologique tardive des cavernes : Les chauves-souris sont considérées comme des occupants emblématiques des grottes. Les colonies, parfois de taille gigantesque, peuvent occuper les cavernes sur de très longues périodes. Ainsi, il se constitue des accumulations de guano dont le volume a favorisé l'exploitation des phosphates, à l'échelle artisanale voire industrielle. L'impact des chauves-souris est triple : leur respiration dégage du CO 2 , leur urine est corrosive, et la minéralisation du guano libère des acides (carbonique, nitrique, sulfurique, phosphorique). Ces substances agressives agissent sur la roche et les concrétions carbonatées, soit par corrosion directe du sol encaissant au contact du guano, soit par condensation-corrosion sur les parois et les plafonds. Bien que tardif dans l'histoire des cavités, l'impact spéléogénétique sur les parois est considérable et peut aller jusqu'à l'ablation de plusieurs mètres d'épaisseur de roche. La présence durable de colonies de chauves-souris est un facteur majeur de spéléogenèse tardive des cavernes, générant des morphologies spécifiques, des dépôts de phosphates conséquents, et un remaniement des parois allant d'un simple rabotage centimétrique jusqu'à des ablations métriques. Ces morphologies de corrosion, qui ont pu être confondues avec des ennoyages, sont probablement responsables de la disparition d'une bonne partie des oeuvres pariétales préhistoriques qui n'ont pu être préservées que dans des conditions bien spécifiques.

Sulfuric acid caves can display a variety of forms, from 3D maze systems, to isolated chambers, and more or less maze-like water table caves. Most of the voids are normally generated at or immediately above the water table, where condensation-corrosion processes are dominant, creating a set of characteristic meso- and micromorphologies. This paper deals with the description of four very typical sulfuric acid water table caves: the Grotte du Chat in Provence (France), the Acqua Fitusa Cave in Sicily (Italy), and the Bad Deutsch Altenburg and Kraushöhle caves in Austria.

First results of a study on hypogenic caves in Sicily are presented. Inactive water-table sulphuric acid caves and 3D maze caves linked to rising of thermal waters rich in H2S were recognized. Cave patterns are guided by structural planes, medium and small scale morphological features are due mainly to condensation-corrosion processes. Calcite and gypsum represent the most common cave minerals. Different types of phosphates linked to the presence of large bat guano deposits were analyzed.

The Marsala area, at the western end of Sicily, has been historically interested by quarry activities, both at surface and underground. The carved rocks are Lower Pleistocene calcarenites, defined as “Calcarenite di Marsala” and referred to the Marsala syntheme. The subterranean quarries, now abandoned, show increasing instability signs becoming in time a risk factor for several causes, among which: a) breakdowns due to poor (weak) strength of rock and to large size of voids; b) progressive weathering of rock; c) effects of the discontinuities in the rock mass with the pillars and/or walls of the underground quarries. These factors contributed to enlargement of the subterranean voids and to their upward propagation, thus triggering several sinkholes. The fast urbanization of the city masked many subterranean quarries causing the loss of memory of their location.In the last decades, numerous sinkholes occurred both in urban sectors and in areas designated for agricultural use, creating extensive damage to buildings and infrastructures.The latest sinkhole episode occurred in the Amabilina area, at the eastern suburbs of Marsala. The depression shows an elliptical perimeter (100×70 m) and a depth of at least 15 m.At the bottom, some rooms up to 5 m high of an underground quarry are visible. From the evidences collected a few days after the event, it was possible to reconstruct the time sequence in the formation of the sinkhole. The collapse started due to the propagation of voids and a first failure of some pillars, and was subsequently followed by a second event, which caused a widening of the depression, due to the redistribution of the stress resulting after early failures.

Il sistema carsico di Sant’Angelo Muxaro si sviluppa in corrispondenza del rilievo gessoso su cui sorge l’abitato omonimo, nel centro Sicilia, in provincia di Agrigento. Tale sistema è costituito da due inghiottitoi attivi (Grotta di Sant’Angelo Muxaro o localmente Grotta Ciavuli e Inghiottitoio Infantino), che si aprono al termine di due valli cieche alla base del versante meridionale del rilievo, e da una risorgenza attiva, ubicata alle pendici del versante nord-occidentale dello stesso rilievo. Le prime esplorazioni speleologiche e l’attività di ricerca in questo sistema nei gessi messiniani della Sicilia, escludendo le segnalazioni del geografo Olinto Marinelli, sono cominciate tra la fine degli anni ’80 e la metà degli anni ‘90, quando è stata topografata e descritta la Grotta di Sant’Angelo Muxaro ed esplorato l’Inghiottitoio Infantino. Solo a partire dal 2004 le ricerche si sono rivolte anche alla risorgenza. Nell’ambito di studi di carattere geomorfologico effettuati nell’area, è stato realizzato un nuovo rilievo topografico e geomorfologico della Grotta di Sant’Angelo Muxaro. In questa occasione sono stati scoperti alcuni rami nuovi, caratterizzati dalla presenza di particolari speleotemi gessosi. In questo contributo verrà descritto il sistema carsico nel suo complesso, anche alla luce delle nuove scoperte.

Cozzo Disi was one of the main sulphur mines in Italy, but after the closure and more than 10 years of desertion, urgent works are now necessary to save it from vandalism and flooding. This big mine contains geological and mineralogical peculiarities, so uncommon to be sometimes unique: this is the case of the “Grandi Garbere” at 3rd level, majestic karst cavities, containing magnificent selenite crystals documented by old miners. The possibility to have a “Sicilian Naica” attracted a multi-disciplinary underground task-force, now exploring the mine underground, in order to inspect old works and their good-safety conditions, and to achieve the rooms/caves of “Grandi Garbere”. This extraordinary discovery should be relevant for the future of this territory. In the past, the mine was characterized by huge safety problems: hydrogen sulfide, carbon dioxide and explosive atmospheres; so, the team involved in actual and future explorations has to move with caution, using adequate equipment and - if necessary - waiting for acceptable environmental conditions created by artificial tools (ventilation, pumping, etc.).

La Grotta dei Personaggi è localizzata in Sicilia occidentale, nei pressi di Monte Magaggiaro, a S del centro abitato di Montevago (AG). Nell’area sono presenti sorgenti termali, caratterizzate da acque cloro-solfate alcalino-terrose con temperatura di circa 40 °C e pH 7. La Grotta dei Personaggi, conosciuta già dai primi anni del 1900 e nota anche per ritrovamenti archeologici, non era mai stata dettagliatamente rilevata e studiata. La cavità si sviluppa prevalentemente in calcari di piattaforma della formazione Inici (Giurassico inf.) e in calcari di scarpata e pelagici della formazione Buccheri (Giurassico inf.-sup.). Si tratta di una cavità sub-orizzontale che presenta uno sviluppo di circa 1,7 km, un dislivello ascendente di 15 m e discendente di 32 m. Il pattern dei condotti è labirintico e strettamente influenzato dalla struttura geologica; non ci sono veri e propri pozzi, ma soltanto fratture che si restringono in profondità; i rami ascendenti sono caratterizzati da cupole che si compenetrano verso l’alto. Tra le altre morfologie si riconoscono buchi da stillicidio, canali di condensazionecorrosione, sfere di condensazione, bocche alimentatrici, pilastri e tramezzi. All’interno della cavità sono presenti anche una colonia di chirotteri e diversi depositi di minerali ancora in fase di studio. L’analisi delle morfologie a grande e media scala e la presenza di acque termali nell'area fanno ipotizzare che la genesi di questa cavità sia legata a processi ipogenici.

The application of numerical modeling to the analysis of the stability of both natural and man-made underground caves is rapidly increasing due to the availability of powerful numerical codes, that can account for either continuum or discontinuum behavior of the rock masses. Numerical methods allow to overcome traditional methods for cave stability analysis that assume too simplified geometrical, geological and geomechanical conditions. Further, they are also able to assess the potential failure mechanisms of underground systems. On the other hand, the application of numerical methods requires availability of a detailed geo-structural survey of the cave, as well as a proper geomechanical characterization of the rock and joint material properties for the pre-processing stage. The present contribution is aimed at describing some aspects related to implementation, and comparison of the outcomes, of two-dimensional or three-dimensional finite element analysis as regards artificial caves with complex geometries excavated within calcarenite rock masses. This type of man-made caves is very common in Southern Italy, and is at the origin of frequent sinkholes, often threatening the built-up areas. In particular, the results from 2-D and 3-D analyses of a case study represented by a cave with complex geometry are presented, showing that 3-D analysis leads to more stable conditions of the rock mass surrounding the cave. This is supposed to be the consequence of the different stress state as calculated by the two analyses, the 2-D one assuming plane strain conditions while the 3-D analysis assumes more general stress conditions.

La presenza di estesi sistemi caveali in sotterraneo, utilizzati nel secolo scorso per l’estrazione di materiale da costruzione in diversi contesti del territorio italiano, di frequente determina situazioni di pericolo per l’ambiente antropizzato, a causa dello sviluppo di processi di instabilità, che possono propagarsi verso l’alto, sino a raggiungere la superficie. Specialmente nei casi in cui la memoria storica della presenza ed estensione delle cave sotterranee è andata persa, lo sviluppo urbanistico dei centri abitati nel corso degli ultimi decenni può avere determinato la realizzazione di abitazioni ed infrastrutture al di sopra, o nelle immediate vicinanze, di zone interessate da complessi sistemi ipogei. Il territorio di Marsala, in Sicilia occidentale, è caratterizzato da numerose cave per l’estrazione della locale roccia calcarenitica, realizzate a profondità variabili da pochi metri a circa 15 m, su livello singolo o su due livelli, seguendo la tecnica di scavo a gallerie e pilastri. Dopo la cessazione dell’attività estrattiva, le cave sono state abbandonate e si è inevitabilmente avviato un processo di decadimento delle proprietà fisiche e meccaniche dell’ammasso roccioso, che spesso ha determinato l’occorrenza di fenomeni di instabilità in sotterraneo. Tali fenomeni, documentati per la zona in esame a partire dagli anni 1960, consistono essenzialmente in collasso e deformazioni delle volte e dei pilastri degli ambienti ipogei. In più situazioni, essi si sono propagati verso l’alto sino a raggiungere la superficie topografica, con formazione di sprofondamenti che hanno coinvolto anche aree urbanizzate, producendo significativi danni. L’ultimo evento è avvenuto nel mese di novembre 2013, ed è presentato nel dettaglio in un altro contributo di questo congresso. Il presente lavoro descrive le analisi numeriche 2D e 3D agli elementi finiti, eseguite su un interessante caso di studio avvenuto nel giugno 2011 nella zona orientale della città di Marsala, prodotto dall’instabilità all’interno di una cava sotterranea, e che ha provocato danni ad un edificio scolastico. La disponibilità del rilievo completo della cava sotterranea, eseguito alcuni anni prima dello sprofondamento, congiuntamente a specifici rilievi geologico-strutturali all’interno degli ambienti ipogei,hanno permesso l’esecuzione di analisi a ritroso per la comprensione dei meccanismi di rottura e l’individuazione dei fattori responsabili dei meccanismi genetici dello sprofondamento. In particolare, verranno evidenziate e discusse le principali differenze riscontrate nel corso dell’esecuzione di analisi bi- e tri-dimensionali.

La presenza di estesi sistemi caveali in sotterraneo, utilizzati nel secolo scorso per l’estrazione di materiale da costruzione in diversi contesti del territorio italiano, di frequente determina situazioni di pericolo per l’ambiente antropizzato, a causa dello sviluppo di processi di instabilità, che possono propagarsi verso l’alto, sino a raggiungere la superficie. Specialmente nei casi in cui la memoria storica della presenza ed estensione delle cave sotterranee è andata persa, lo sviluppo urbanistico dei centri abitati nel corso degli ultimi decenni può avere determinato la realizzazione di abitazioni ed infrastrutture al di sopra, o nelle immediate vicinanze, di zone interessate da complessi sistemi ipogei. Il territorio di Marsala, in Sicilia occidentale, è caratterizzato da numerose cave per l’estrazione della locale roccia calcarenitica, realizzate a profondità variabili da pochi metri a circa 15 m, su livello singolo o su due livelli, seguendo la tecnica di scavo a gallerie e pilastri. Dopo la cessazione dell’attività estrattiva, le cave sono state abbandonate e si è inevitabilmente avviato un processo di decadimento delle proprietà fisiche e meccaniche dell’ammasso roccioso, che spesso ha determinato l’occorrenza di fenomeni di instabilità in sotterraneo. Tali fenomeni, documentati per la zona in esame a partire dagli anni 1960, consistono essenzialmente in collasso e deformazioni delle volte e dei pilastri degli ambienti ipogei. In più situazioni, essi si sono propagati verso l’alto sino a raggiungere la superficie topografica, con formazione di sprofondamenti che hanno coinvolto anche aree urbanizzate, producendo significativi danni. L’ultimo evento è avvenuto nel mese di novembre 2013, ed è presentato nel dettaglio in un altro contributo di questo congresso. Il presente lavoro descrive le analisi numeriche 2D e 3D agli elementi finiti, eseguite su un interessante caso di studio avvenuto nel giugno 2011 nella zona orientale della città di Marsala, prodotto dall’instabilità all’interno di una cava sotterranea, e che ha provocato danni ad un edificio scolastico. La disponibilità del rilievo completo della cava sotterranea, eseguito alcuni anni prima dello sprofondamento, congiuntamente a specifici rilievi geologico-strutturali all’interno degli ambienti ipogei, hanno permesso l’esecuzione di analisi a ritroso per la comprensione dei meccanismi di rottura e l’individuazione dei fattori responsabili dei meccanismi genetici dello sprofondamento. In particolare, verranno evidenziate e discusse le principali differenze riscontrate nel corso dell’esecuzione di analisi bi- e tri-dimensionali.

The Map Sheet 1:50.000 595 ”Palermo” includes marine and land areas of the topographic map sheet “Palermo”. The map sheet “Palermo” (Palermo Province) covers a part of the Sicily Fold and Thrust Belt (FTB) which has developed along the plate boundary between Africa and Europe in the Central Mediterranean. The Sicily FTB links the African Maghrebide to the Calabrian arc and Southern Apennines. The FTB and its submerged western and northern extensions are part- ly located between the Sardinia block and the Pelagian-Ionian sector, and partly beneath the central southern Tyrrhenian Sea. In this sector of the Mediterranean area, the main compressional move- ments, after the Paleogene Alpine orogeny, began with the latest Oligocene-Early Miocene counterclockwise rotation of Corsica-Sardinia, believed to represent a volcanic arc, and its collision with the African continental margin. Thrusting oc- curred in connection with the westward subduction of the Adriatic and Ionian lithosphere beneath the Corsica-Sardinia block. Today, a westward subduction is indicated by a North-dipping Benioff zone, as deep as 400 km, west of Calabria and the Apennines, and the related calc- alkaline volcanism in the Eolian Islands. Subduction and thrusting are contempo- raneous with a back arc-type extension in the Tyrrhenian Sea.186 LAND AREAS geomorphoLogy Three different sectors can be distinguished in Sheet 595: 1) the Palermo and Bagheria coastal plains, characterized by several poly- cyclic marine terraces organized in different orders; 2) the isolated carbonate reliefs of Monte Pellegrino and Monte Catalfano; 3) the internal Belmonte Mezzagno highlands and the Oreto and Eleuterio river valleys. The geomorphological evolution of the area has been controlled by strong down-cutting and dismantling processes that have produced both the erosion of thick volumes of mainly Tertiary terrigenous deposits and the exhumation of mainly Mesozoic carbonate rocks. Due to tectonic uplifting, these proces- ses are intensely developed on ”soft rocks “(Numidian Flysch clayey deposits), producing large river valleys with slopes affected by water erosion and surficial landslides (valleys of Fiume Oreto, Fiume Eleuterio and Fiume Milicia); they have, however, considerably slowed down along the blocks of more resistant rock (Mesozoic-Tertiary carbonate units), forming the wide Palermo Mountains. At the present-day, relict (planation surfaces and abandoned valleys), structural (fault/fault-line scarps) and karst (sinkholes and polje) forms occur in the highlan- ds. The geomorphological setting of the coastal areas has been influenced more by significant Quaternary extensional tectonics that originated the drowning of the northern sectors of the Sicilian chain in the Tyrrhenian Sea above which the marine deposition was deposited (Marsala synthem). The uplifting, involving also the lowered blocks, has resulted in the progressive retreat of the sea that gave origin to a succession of marine terraces, Ionian-Latest Pleistocene in age, and fi- nally the emersion of the present-day coastal depressions (Palermo and Bagheria plains). During the Upper Pleistocene to Holocene, the uplifting rates reached values generally lower than 0.1 m/ky. stratIgraphy The carbonate and terrigenous rock facies analysis and stratigraphy led to the recognition of large Paleozoic to Miocene sedimentary bodies pertaining to diffe- rent and separate crustal paleogeographic domains; the former, developed along the African passive continental margin and the adjacent Tethyan ocean. The “Tethyan” successions correspond to the deep clayey carbonate and vol- canoclastic rocks known to have been deposited in the Sicilide Domain. The pas- sive margin rock bodies are shallow water carbonates, deep water carbonates and 187 siliceous carbonates that were deposited in domains, locally known as Panormide, Trapanese and, Imerese. Terrigenous, evaporitic and clastic-carbonate rocks, Miocene to Pleistocene in age, formed during the foredeep evolution of the Sicilian FTB. A detailed stratigraphy of the rock-successions is summarized in the paragraph “Legend of the Palermo Sheet”. Quaternary continental deposits have been mapped as unconformity-bounded stratigraphic units limited by lower and upper unconformities, locally marked by palaeosoils, due to erosion/depositional processes, marine/sub-aerial processes or non-depositional events. Locally, the upper boundaries are the present-day topo- graphic surface. The detection of some unconformities of regional extent allowed us to define several synthems. The Marsala synthem is a Lower Pleistocene body of marine/coastal deposits, with abundant fossils; its lower boundary is a mari- ne erosion surface cutting pre-Quaternary rocks. The Buonfornello-Campofelice synthem is composed of middle Pleistocene marine deposits covering abrasion surfaces above the coastal stepped blocks. The Polisano synthem is made up of aeolian sandstones and sands with intercalations of breccias talus, late Middle Pleistocene in age (OIS 6); its lower boundary is a non-depositional surface at the top of older rocks. Eleuterio and Milicia synthems are made up of Middle-Upper Pleistocene, mainly fluvial, deposits deposited on river terrace surfaces; their lo- wer boundary is a stream erosion surface. The Benincasa synthem includes colluvial Middle-Upper Pleistocene deposits of Qz-sandstones interbedded with stone-line, palaeosoils, Fe-rich layers and no- dular concretions. Its lower boundary is an unconformity above the Buonfornello- Campofelice synthem, the upper one is the base of the Capo Plaia synthem of the present soil. The Barcarello synthem encompasses marine/coastal conglomerates and are- nites, with a rich warm-temperate “Senegal fauna” including Strombus bubonius; it is located on two orders of marine terraces (OISs 5e and 5c or 5a) and laterally passes into welded colluvial deposits whose age is correlated with the OIS 5. The lower boundary of the synthem is a marine abrasion surface, laterally extending to a continental erosion surface; the latter is cutting the Polisano synthem or older rocks. The Raffo Rosso synthem consists of aeolian sandstones and sands, collu- vial or gravitational deposits and thick stratified slope deposits of the last glacial climatic event (OISs 4-2); the lower boundary is a non-depositional surface at the top of the Barcarello synthem or older rocks. The Capo Plaia synthem is made up of coastal to continental deposits of the last glacial climatic event of the end - Holocene age (OISs 2-1); its lower boundary is formed by variously origina- ted erosion or non-depositional surfaces; the upper boundary is the topographic surface.188 struCturaL graIn The Paleozoic to Cenozoic, mainly carbonate sedimentary bodies, developed in different sectors of the African passive continental margin and the adjacent Tethyan ocean and were progressively accreted in a pile of tectonic units and are now exposed to form the Sicilian fold and thrust belt. To define the extension and setting of these bodies versus their internal facies pattern, we individuate them as Structural-Stratigraphic Units (U.S.S.), described as large geological bodies per- taining to original paleogeographic domains from where they were removed and later deformed. These bodies are bounded by clearly mappable tectonic features (faults, thrust, etc.) and each of them is characterized by homogeneous lithologies and similar structural behaviours and settings. The outcropping tectonic edifice, in the “Palermo” Sheet, is composed of se- veral U.S.S., which can be locally subdivided into tectonic units of minor order. These subunits have been mapped on the basis of their tectonic relationships. Some U.S.S. have been identified, starting from the geometrically highest and most internal in the FTB. 1) U.S.S. deriving from the deformation of the Sicilide domain succession: - U.S.S. Tusa-Troina outcropping in the south-eastern sector, overlying the Numidian Flysch deposits. 2) U.S.S. deriving from the deformation of the Imerese domain succession and its overlying numidian flysch basin. The units widely outcrop in the cen- tral and southern sector of the geological sheet where Mesozoic deep water carbonates and their oligo-miocene numidian flysch covers are deformed, with the latter often slightly detached from the carbonate substrate. Among them we distinguished: - U.S.S. Sagana - Belmonte Mezzagno, in the western sector, where we indi- viduated the sub-unit Pizzuta-S.Cristina; - U.S.S. Monte Cane-San Calogero, in the eastern sector, subdivided into a) the subunit Monte Cane-S. Onofrio, overlying b) the subunit Bizolelli; 3) U.S.S. deriving from the deformation of the Panormide Domain. The U.S.S. consists of Meso-Cenozoic shelf to pelagic carbonates and the often detached nu- midian flysch cover, pertaining to the U.S.S. M. Gallo-M. Palmeto, forming the margin of the Panormide Platform. It outcrops only at Monte Pellegrino (subunit Pellegrino). 4) U.S.S. deriving from the deformation of the Trapanese domain. It is recognizable only in the seismic profile crossing the eastern sector where it is overlain by the U.S.S. Sagana - Belmonte Mezzagno. Southwards, it oucrops at Monte Balatelle (U.S.S. Kumeta-Balatelle).189 Structural evolution The tectonic edifice outcropping and buried beneath the area of the Palermo Sheet is the result of several deformational events that have taken place since the Triassic, deforming complexly the sedimentary successions deposited during the Mesozoic-Pleistocene. After the detachment from their crystalline basement the original sedimentary bodies were progressively accreted in a pile of tectonic units now exposed in the Sicilian chain. Two main events have occurred during the Miocene and Pleistocene time interval. They are respectively characterized by compression and transpression. Contraction originally involved the Tethyan domains and the internal domains of the continental margin, whose deep water meso-cenozoic carbonates formed the structurally highest tectonic units in the chain. The occurrence of intrastratal decollement originated duplex geometries. Since the Messinian, the deformation moved at depth, progressively involving the carbonate platform rock bodies in large E-W antiforms that were successively (during Late Pliocene) folded by NE- SW structures. The transpressional event is proved by NNW-SSE and NE-SW transcurrent and transpressive structures (dextral); it involves the deep-seated car- bonate platform-forming fold structures and severe uplifting that induces reimbri- cation in the overlying Imerese deep-water units. This transpressive event accom- panies the paleomagnetically evidenced thrust rotations between the Late Miocene and the Early Pleistocene. An abrupt change in the tectonic transport direction of the two compressional structure systems is explained taking into account the 120° clockwise rotations based on the paleomagnetic results of ChanneL et alii (1980, 1990); speranza et alii (2000). As a consequence the present day outcropping structural attitude of the structures (and consequently of the deformation fields) do not coincide with the original trends. The compressional and traspressional structures are down faulted northwards by the extensional tectonics. MARINE AREAS In the marine areas, we distinguished different morphological environments, from beaches through the offshore (inner shelf), to the outer shelf and upper slope where two confined slope basins (Palermo and Termini basins, separated by the Monte Catalfano salient) represent the south-western margin of the large Cefalù basin. The substrate of these basins is represented by the Sicilian FTB tectonic units and their syn- and post-orogenic covers. The area shows a lateral variation from the rocky shores, in front of Monte Pellegrino and Monte Catalfano and in the eastern sector, to the beaches mainly in the central sector.190 Important physiographic changes, as shelf width and gradient and different coast orientations, characterise the continental shelf and slope and influence the hydrodynamic processes (wave activity and shelf current patterns). The continental shelf reaches 250 km2 and shows width values ranging from 1.5 km in the Capo Zafferano offshore to 8,0 km in the gulf of Termini, whereas gradient values range between 1° and 8°. The continental shelf has been subdi- vided into an inner infralittoral domain down to a 30 - 35 m water depth, which is characterized by an abrasion platform at different depths, and the outer shelf domain extends to the shelf edge. The shelf edge, which is both depositional and erosional, located at water depths between 120 m and 140 m, rises to lower depths at the canyon heads. Dominant morphological features along the continental slope are the submari- ne erosive conduits, locally interesting also the continental shelf. The heads of the conduits are characterised by severe episodes of retrogressive failure and incised by small gullies. Some (the Oreto and Eleuterio canyons) are directly linked to rivers and were connected during the last glacial maximum through incised val- leys, now buried by transgressive to highstand deposits. In the central sector of the Gulf of Palermo, we pinpointed almost three pockmarks, depressions tens of meters deep, originating from escaping fluids, while in the western sector of the gulf the same phenomena caused the occurrence of isolated or aligned, outcrop- ping or buried mounds. Finally anthropic features largely characterize the seabottom mainly in the inner shelf. seIsmostratIgraphy and stratIgraphIC settIng The buried sedimentary succession has been investigated by means of a close grid of single and multichannel seismic lines. On the whole, three seismic units (S, C and A) have been distinguished. The S seismic unit represents the offshore prolongation of the Meso-Cenozoic units of the Sicilian FTB and their syn- and post-orogenic cover. They are ge- nerally topped by a pronounced, erosive unconformity, correlated to the exten- sive Messinian horizon, generated during the last phases of the Mediterranean Salinity Crisis (5.5 Ma), and covered by a transparent seismic unit representing the Globigerina - bearing pelagic chalk (Trubi) and the Upper (?) Pliocene slope to shelfal deposits. The C seismic unit is represented by a prograding succession of 4° to 7° dip- ping horizons, which have been correlated with the regressive upper Pliocene- Pleistocene deposits, topped by the regional wide, erosional truncation related to the last glacioeustatic sea level fall, correlated with the δ18 O isotopic stage 2. The A seismic unit corresponds to the Late Pleistocene to Holocene 191 depositional sequence (SDTQ) with sigmoidal to tabular geometry; the deposi- tional sequence consists of a Falling Stage and Lowstand Systems Tracts with a progadational pattern controlling a relevant out-building of the shelf margin and a sedimentary wedge, of variable thickness, made up of the Transgressive (TST) and the Highstand (HST) Systems Tracts. The TST, developed during the Holocene sea level rise, shows a retrograda- tional stacking pattern, while the HST, deposited during the last 6 ka b.P., shows aggradational to faintly progradational geometries, related to the development of a littoral depositional system. Along the upper slope, turbiditic systems, characterized by erosive conduits and scattered mass wasting, developed extensively during the Late Pleistocene to Holocene. Surficial sediments of the continental shelf and slope The continental shelf and slope of the Palermo sheet are veneered with uncon- solidated, late Holocene in age, clastic and biogenic carbonate (Palermo gulf) and in second order, lithoclastic (Termini gulf) sediments. Deposits are composed of sands, relict Pleistocene and older carbonate parti- cles, abundant biogenic carbonate granules and algal-coated grains. In the outer shelf and upper slope, deposits are predominantly fine to very fine grained (silts and silty clays). The inner shelf is veneered by a mixture of gravel (rarely), coarse to fine sands, silts and clays, showing a general trend of decrea- sing size in a general seaward direction. From the sedimentary and the morphological features, four different depo- sitional systems have been distinguished: foreshore depositional systems, inner shelf depositional systems, outer shelf depositional systems and upper slope de- positional systems, mapped as g8 , g19 , g21 , m2 respectively. The systems are laterally gradational and linked by a variety of sedimentary processes. Shallow marine environments (up to a 50 m water depth) are generally characterized by biogenic sediments while terrigenous and carbonate clastic sedi- ments supplied by rivers or coastal erosion locally prevail. The most important facies of the infralittoral domain consists of Posidonia oceanica and Cymodocea nodosa meadows, which extensively cover the rocky substrate or the sandy floors the former and the muddy floors the latter. teCtonIC evoLutIon of the offshore areas The present day structural setting reconstructed in the Palermo sheet marine sectors appears the same as the tectonic edifice depicted on the mainland: it has 192 been interpreted as a consequence of the complex Neogene to Quaternary tectonic evolution. The compressive tectonics, responsible for the wedging of the present day submerged thrust sheets, developed during the Late Miocene span interval. This event was followed by transpressive tectonics that faulted and folded the Late Neogene to Pliocene infill by activation of high-angle, deep faults. During the Pleistocene, extensional tectonics accounted for opening and subsidence of structural lows. Present day active tectonics is still going on, as documented by compressive- transpressive focal mechanisms of shallow to deep, low amplitude earthquakes occurring along the offshore between the Sicilian coast and Ustica Island. A few middle-late Pleistocene marine terraces, outcropping along the coast at different levels, suggest a prolonged, faintly tectonic uplift. On the whole, the Plio-Quaternary geological evolution of the offshore area appears to be constrained by a strong interaction between eustatic sea level chan- ges, sediment supply and tectonics, recorded by strain features and enhanced un- conformities crossing the basin fill.

Vengono presentati i risultati preliminari di uno studio condotto su alcune grotte ipogeniche della Sicilia, ritenute fino a questo momento di natura epigenica: il sistema carsico di Monte Inici e la Grotta dell’Acqua Fitusa. Il primo sistema è localizzato nella Sicilia nordoccidentale lungo il versante sudorientale di Monte Inici. È costituito da due cavità, la Grotta dell’Eremita e l’Abisso dei Cocci, che si sviluppano in calcari e calcari dolomitici della Fm. Inici (Giura inf.) e in calcari ad ammoniti della Fm. Buccheri (Giura medio-sup.). Si tratta di sistemi tridimensionali freatici che raggiungono una lunghezza di oltre 2km e una profondità superiore a 300m. Sono caratterizzati da diversi livelli di gallerie, spesso impostate lungo piani di strato, connesse da profondi pozzi che seguono sistemi di fratture subverticali o piani di faglia. Lungo le pareti e il soffitto degli ambienti ipogei sono state riconosciute numerose morfologie legate a processi di condensazione-corrosione, quali megascallops e cupole di diverse dimensioni. I depositi chimici consistono di speleotemi carbonatici, croste di gesso, aghi di aragonite, croste di carbonato-apatite e altre mineralizzazioni in fase di analisi. Entrambe le grotte sono prive di sedimenti di natura alluvionale. L’intero sistema è verosimilmente connesso alla risalita di acque termali sulfuree che attualmente emergono a Est e a quota inferiore rispetto alle cavità. L’evoluzione e l’ampliamento dei vuoti carsici sembrano inoltre essere legati a flussi d’aria che favoriscono processi di corrosione per condensazione. La Grotta dell’Acqua Fitusa è localizzata nella Sicilia centrale, lungo la scarpata nordorientale del rilievo La Montagnola. La grotta si sviluppa su almeno tre livelli di gallerie per circa 700m raggiungendo una profondità di 25m, lungo brecce carbonatiche a rudiste, risedimentate, della Fm. Crisanti (Creta sup.). Si tratta di una grotta sulfurica epifreatica inattiva, formatasi in corrispondenza della superficie piezometrica. Attualmente la sorgente di acqua sulfurea (T=25°C) è ubicata a circa 300m a nordovest e ad una quota inferiore rispetto alla cavità. La grotta è caratterizzata da numerose forme originate da processi di corrosione per condensazione, quali: cupole, nicchie parietali a diversa quota, megascallops, boxwork, canali di condensazione lungo il soffitto, ecc. Nicchie di sostituzione connesse a processi di corrosione-sostituzione sono presenti in molti ambienti della grotta. Intagli a tetto piatto, dovuti a corrosione laterale da parte della tavola d’acqua termale, incidono le pareti della grotta a diversa altitudine, registrando antiche fasi di abbassamento del livello di base dell’erosione. Cristalli e croste di gesso, gesso massivo sono diffusi. L’origine della cavità è legata a fenomeni di corrosione della roccia carbonatica con sostituzione di gesso da parte delle acque sulfuree termali. In particolare, l’allargamento dei vuoti e la genesi delle principali forme sono legati al degassamento di H2S nell’atmosfera grotta, ossidazione dei solfuri e convezione termale che produce intensi processi di corrosione per condensazione al di sopra della superficie piezometrica.

The Northern Madonie Mountains (Northern-Central Sicily), sector of the Sicilian Maghrebian chain, consist of a tectonic thrust system developed through two subsequent main contractional events: 1) a shallow-seated compressional event developed during the Middle-Upper Miocene; 2) a deep-seated transpressional event occuring since the Late Miocene. Lower Pliocene (Trubi) to Quaternary clastic deposits unconformably lie on the tectonic units and are partially involved by deformation. In the selected area, syntectonic sedimentary basins characters are able to define the timing of deformation only until the Lower Pliocene; to resolve this gap of information application of quantitative geomorphic techniques, based on relationships between tectonics and hydrographic network development could contribute to recognize and characterize Quaternary structures in areas where clayey/marly deposits, widely outcropping, are not marked by pervasive tectonic deformations. In order to define the geological setting of the study area and to detect Quaternary tectonic structures, geological, structural and geomorphological analyses have been carried out. Geological and structural analyses have shown: 1) characters and style of deformation of fold structures: two main systems of folds have been recognized - the early system NW-SE-trending is refolded by a later system (trends in the E-W to NE-SW range); 2) orientation and kinematics of faults related to superimposed compressional events: an early thrust system characterized by SW-ward tectonic transport; a later transpressive system consistent with a maximum compression oriented N-S ± 20°, and nearly horizontal. Although the occurence of two compressional deformation events, interplaying in the construction of the Sicilian chain, is well-known, the field data, here collected, help to better characterize the relationship between shallow-seated and deep-seated structures. Due to rare and thin Quaternary deposits, quantitative geomorphic analysis has been performed on the hydrographic network of the study area, because the river drainage of Sicily is believed to have developed during the Quaternary age. In particular, have been carried out: 1) azimuthal distribution analysis, by cumulative length, of stream channels related to different orders, taking into account structurally and lithologically homogeneous areas to evaluate the influence of Quaternary tectonics on the geometry of drainage patterns; NNW-SSE, NNE-SSW, E-W and N-S domains have been evidenced in lower orders of channels; 2) “azimuthal transect method”, performed along 16 suitable segments crossing previously inferred fault zones, able to detect possible Quaternary strike-slip kinematics. Progressive apparent rotations of stream channels have been found, documenting the occurence along the main rivers of Quaternary faults and suggesting both right-lateral (NNW-SSE oriented) and left-lateral (NE-SW oriented) kinematic components. The multidisciplinary approach used suggests the geological/geomorphological setting of the study area is influenced by Quaternary faults with strike-slip component, highlighting a general congruency between hydrography and tectonics.