Karst of Sicily and its conservation

In Sicily, karst is well developed and exhibits different types of landscapes due to the wide distribution of soluble rocks in different geological and environmental settings. Karst affects both carbonate rocks, outcropping in the northwest and central sectors of the Apennine chain and in the foreland area, and evaporite rocks, mainly gypsum, that characterize the central and the southern parts of the island. The carbonate and gypsum karsts show a great variety of surface landforms, such as karren, dolines, poljes, blind valleys, and fluvio-karst canyons, as well as cave systems. Karst areas in Sicily represent extraordinary environments for the study of solution forms. In addition, they are of great environmental value because they contain a variety of habitats that hold species of biogeographic significance. Unfortunately, karst areas are increasingly threatened by human activity, mainly in the form of grazing and other agricultural practices, wildfires, quarrying, urbanization, building of rural homes, and infrastructure development. The value of karst features has been recognized by the Sicilian Regional Government since 1981 when it enacted laws to create several nature reserves to preserve the peculiar karst landscapes, including caves. At present, the state of conservation of karst areas in Sicily may be considered to be at an acceptable level, yet numerous issues and difficulties need to be overcome for the effective protection and enhancement of karstlands

Geomorphological evolution of western Sicily, Italy

This paper proposes a morphoevolutionary model for western Sicily. Sicily is a chain–foredeep–foreland ­system still being built, with tectonic activity involving uplift which tends to create new relief. To reconstruct the ­morphoevolutionary model, geological, and geomorphological studies were done on the basis of field survey and aerial photographic interpretation. The collected data show large areas characterized by specific geological, geomorphological, and topographical settings with rocks, landforms, and landscapes progressively older from south to north Sicily. The achieved results display: (1) gradual emersion of new areas due to uplift, its interaction with the Quaternary ­glacio-eustatic oscillations of the sea level, and the following production of a flight of stair-steps of uplifted marine ­terraces in southern Sicily, which migrates progressively upward and inwards; in response to the uplift (2) triggering of down-cutting processes that gradually dismantle the oldest terraces; (3) competition between uplift and down-cutting processes, which is responsible for the genesis of river valleys and isolated rounded hills in central Sicily; (4) continuous deepening over time that results in the exhumation of older and more resistant rocks in northern Sicily, where the higher heights of Sicily are realized and the older forms are retained; (5) extensional tectonic event in the northern end of Sicily, that produces the collapse of large blocks drowned in the Tyrrhenian Sea and sealed by coastal-marine deposits during the Calabrian stage; (6) trigger of uplift again in the previously subsiding blocks and its interaction with coastal processes and sea level fluctuations, which produce successions of marine terraces during the Middle–Upper Pleistocene stages

DETECTION OF PLIO-QUATERNARY FAULTS IN MADONIE MOUNTAINS (SICILY) BY USING QUANTITATIVE GEOMORPHIC AND STRUCTURAL GEOLOGY ANALYSES

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

Fogli 609-596, Termini Imerese-Capo Plaia

Il Servizio Geologico Nazionale ha unificato i Fogli 609 "Termini Imerese" e 596 "Capo Plaia" in un unico Foglio denominato 609/596 "Termini Imerese-Capo Plaia" allo scopo di uniformare i rilievi e raccoglierne la descrizione in un unico volume delle Note Illustrative. Il Foglio 609/596 "Termini Imerese-Capo Plaia" della Carta Geologica d’Italia in scala 1:50.000 è stato realizzato nell’ambito del Progetto CARG con i fondi della Legge 67/88 - Legge 226/99 con una convenzione tra Servizio Geologico Nazionale ora ISPRA) e Regione Siciliana. Le aree ricadono interamente nella Provincia di Palermo, comprendono la fascia marina del Golfo di Termini Imerese fino al promontorio di Capo Plaia, la regione dei Monti di Termini Imerese e Trabia ad ovest e il settore occidentale del gruppo montuoso delle Madonie ad est. Tra questi rilievi si sviluppa un’ampio settore collinare inciso dai fiumi Torto e Imera settentrionale (o Fiume Grande)

Geology of Monte Gallo (Palermo Mts, NW Sicily)

The promontory of Monte Gallo (Palermo, NW Sicily) is a spectacular site where Upper Triassic-Eocene carbonate platform rocks and Quaternary continental to marine deposits are well exposed. A Mesozoic-Paleogene rock succession allows the potential visitor to easily detect the features and the evolution of the Panormide carbonate platform, a shallow-water paleogeographic domain of the Southern Tethyan margin. Quaternary deposits, as well many landforms, enable the visitor to directly identify the interplay between climate changes, tectonics and fluctuations of marine level that occurred during the Quaternary Period. A detailed geological map (1:15,000 mapping scale) is presented, accompanied by a stratigraphic correlation of logged sections and morpho-stratigraphic and tectonic schemes of the area, aimed at highlighting the geological heritage of Monte Gallo in support of the establishment of a Geosite. The Geological Map and relevant explanatory notes should be used as cartographic support and as a field trip guide for possible geological itineraries

The Middle-Late Quaternary littoral deposits of Western Sicily coastal belt (southern Italy): sedimentology and geomorphology

A multidisciplinary study has been carried out on the littoral deposits located along the western Sicily coastal belt, central Mediterranean region, with the aim of unravelling their origin and evolution through analysis of their lithology, texture, sedimentary structures, and geomorphological features. The deposits crop out between the towns of Trapani and Marsala and are distributed from the present-day coastline up to 120 m above sea level, forming four major discrete ridges in the landscape, each of separated by topographic depressions with flat or slightly concave upwards surfaces. The ridges ranging between 5 to 30 m in height, display a NNE-SSW trend almost parallel to the present-day coastline, and are 1–2 km apart from each other. The littoral deposits rest above an extensive unconformity surface separating them from the Lower Pleistocene calcarenite unit (Marsala synthem) or older (Oligocene-Miocene) mostly marly-shaley and arenaceous units. Along the ridges, the following four lithofacies have been encountered, from the bottom to the top: i) transgressive lag composed of rounded pebbles, sandstones, and breccias of Tertiary limestone in a silty matrix containing small fragments of Mollusca shells; ii) medium to coarse, well sorted sands with plane-parallel lamination, passing upwards to medium-to-coarse sand containing polygenic well rounded pebbles interpreted as longshore current and wave-reworked river mouth deposits; iii) tabular or lens shaped, well stratified calcarenites with low- and high-angle lamination, interpreted as upper shoreface and foreshore deposits; iv) medium-to-coarse, cemented, mostly carbonate-rich sands with subordinate percentage of quartz granules, containing sparse reworked foraminifera and terrestrial gastropods, showing evident large-scale tabular and concave cross-lamination (each lamina is 0.5–2 cm thick). The deposits consisting of this lithofacies form convex elongated sedimentary bodies with thickness ranging between 2 and 15 m where up to three sub-units, separated from each other by upward concave erosional surfaces marked by paleosoils, can be recognized. This lithofacies is interpreted to be associated with an aeolian dune sedimentary complex developed on a coastal environment. In addition, in the topographic depressions separating the ridges, coastal fine-grained sandstone containing sparse marine fauna with fragments of shells of bivalves and gastropods and matrix-supported well-rounded quartz-arenitic pebbles suggests a deposition in a fluvial-influenced coastal lagoon environment. The overall geomorphological setting, stratigraphy and sedimentary features observed in the study area suggest the development of a complex coastal barrier environment associated with shoreface, beach-barrier coastal dunes and back barrier lagoon and fluvial-coastal system. This resulted from the complex interplay between coastal, aeolian and fluvial processes in an area intensely which during the Middle-Late Pleistocene has been affected by sea-level fluctuations and tectonic uplift inducing the progressive westward migration of the coastline to the present-day position