Calpionellid biostratigraphy of the Upper Tithonian–Upper Valanginian interval in Western Sicily (Italy)

A revision of the calpionellid bio-chronostratigraphy in Western Sicily (Italy) was carried out, in order to update the taxonomy of this group, through the identification of some genera (Borziella, Longicollaria, Chitinoidella, Dobeniella, Sturiella, Borzaiella and Praecalpionellites) and species (Remaniella catalanoi Pop, Remaniella duranddelgai Pop, Remaniella colomi Pop, Remaniella borzai Pop, Remaniella filipescui Pop) recorded for the first time in the area. The studied sections, belonging to the Trapanese and Saccense Domains (Western Sicily), include at the base the upper portion of the Rosso Ammonitico Unit (Upper Tithonian), followed by the Lattimusa Formation (Lower Cretaceous). The quantitative and biostratigraphic analysis of the calpionellid assemblages allowed us to identify 13 assemblages and to define some important bioevents for the Upper Tithonian–Valangianian interval. The recorded calpionellid bioevents allowed us to recognize Zone/Subzone schema, which have been correlated with the bio-chronostratigraphy previously proposed for the Western Tethys. Editorial handling: M. Chiari (Guest) & J.-P. Billon-Bruyat     

Petrography and decay of a marly limestone in the cloister of a medieval cathedral in Sicily

This paper deals with a significant process of decohesion of a marly limestone, taking place in the cloister of the medieval Cathedral of Cefalù, a pleasant town on the northern coast of Sicily. After desalination with deionised water and consolidation with ethyl silicate, the decay of the stone became faster. The aim of our study is to characterise the stony material and investigate the observed decay phenomena. The stone, that is a poor building material indeed, is characterised by means of petrographical, chemical and physical analyses on samples taken from the monument. Furthermore, experimental tests are performed in the laboratory in order to highlight the causes of incompatibility between the stone and the applied treatments.     

Seven landslide dams of old seismic origin in southeastern Sicily (Italy)

This paper focuses on origin, morphology and evolution of seven landslide dams in southeastern Sicily. These landforms are part of a set of 146 landslides recently recognised in this area, which was hitherto considered to have little or no slope instability. Southeastern Sicily consists of a plateau (the Hyblaean Mountains) incised by canyons and surrounded by lower lands. It is underlain mostly by subhorizontal, moderately to well-lithified carbonate rocks. Relief is low.Several lines of evidence justify the assumption of a seismic trigger for the landslides in this area: (1) the geo-climatic environment is not favourable to landsliding, (2) low-angle basal shear surfaces are very frequent, (3) landslide distribution is consistent with the known magnitude–distance relationships for earthquake-induced landslides, (4) historical documents testify to earthquake-triggered slope instability and (5) a specific landslide can be exactly dated.The phenomena illustrated here include six rock slides (one with a debris-flow component) and one rock fall. Slip surfaces are mostly non-circular. Landslide volume ranges from about 50×10³ to 34×10⁶ m³.With reference to the Costa and Schuster [Geol. Soc. Am. Bull. 100 (1988) 1054] classification of landslide dams, five cases belong to type II (spanning the entire valley), and two to type IV (failures from both valley sides, with frontal or side contact between failed masses). With reference to Crozier and Pillans [Catena 18 (1991) 471] classification of landslide lakes, all cases show a main valley lake while tributary valley, back and supra lakes are sporadically present. One damming is attributable to the 1693 earthquake with certainty; another damming, to the same earthquake with high probability. Three dams were reincised, one breached or reincised, one is slightly reincised and two more or less intact; correspondingly, five silting up deposits were reincised, one is being reincised at present and two are still under formation.     

Isotope distribution of dissolved carbonate species in southeastern coastal aquifers of Sicily (Italy)

Concentrations of major ions and the δ¹³C composition of dissolved inorganic carbon in groundwater and submarine groundwater discharges in the area between Siracusa and Ragusa provinces, southeastern Sicily, representing coastal carbonate aquifers, are presented and discussed. Most of groundwater analysed belongs to calcium bicarbonate type, in agreement with the geological nature of carbonate host rocks. Carbonate groundwater acquires, besides the dissolution of carbonate minerals, dissolved carbon (and the relative isotopic composition) from the atmosphere and from soil biological activity. In fact, δ¹³C values and total dissolved inorganic carbon contents show that both these sources contribute to carbon dissolved species in the waters studied. Finally, mixing with seawater in the second main factor of groundwater mineralization Copyright © 2007 John Wiley & Sons, Ltd.     

Sedimentation, fracturing and sliding on a pelagic plateau margin: the Middle Jurassic to Lower Cretaceous succession of Rocca Busambra (Western Sicily, Italy)

The Jurassic succession of Rocca Busambra consists of two lithostratigraphic units: a pile of peritidal limestones several hundreds of metres thick (Inici Formation: Hettangian to Sinemurian) and a 2 to 15 m thick sequence of Rosso Ammonitico‐type pelagic limestones (Toarcian? to lowermost Berriasian). An extensive interval of non‐deposition is evidenced by a thick Fe–Mn oxide crust on the bounding disconformity and is recorded partially in the material contained within a complex network of neptunian dykes and sills. Seven lithofacies are distinguished in the Rosso Ammonitico. These lithofacies show that the Rosso Ammonitico limestones differ from most analogues both in Sicily and elsewhere: sediments are mostly grain‐supported and non‐nodular; obviously bottom currents were important during deposition of these sediments. These currents were pulsating at different frequencies and induced winnowing, intraclast production and early cement precipitation. Other Rosso Ammonitico lithosomes of Late Jurassic to earliest Cretaceous age, usually decimetre thick and discontinuous, overlie the Inici Formation without any Fe–Mn crust; their anomalous stratigraphical and geometrical relationships show that they were deposited on an inclined, stepped, erosional surface incised in the sub‐horizontal Inici Formation. This ancient escarpment is interpreted as the result of a mainly gravitational collapse of the margin of a pelagic plateau. Such mass wasting was probably due to the backstepping of the tectonic plateau–basin margin that is not observable directly, but may be inferred from circumstantial evidence. This observation clearly shows that tectonic activity affected the Rocca Busambra sector of the West Tethys continental margins a few tens of millions of years after the end of the rifting stage. The anomalous Rosso Ammonitico sediments are the only indication of the escarpment and their occurrence in the stratigraphic record is probably more widespread than reported in the literature. More accurate palaeoenvironmental and palaeogeographic reconstructions may depend on the identification of these sediments.     

Evolution of a carbonate delta generated by gateway‐funnelling of episodic currents

Cool‐water carbonate sedimentation has dominated Mediterranean shelves since the Early Pliocene. Skeletal sand and gravel herein consist of remains of heterozoan organisms, which are susceptible to reworking due to weak early cementation in non‐tropical waters. This study documents the Lower Pleistocene carbonate wedge of Favignana Island (Italy), which prograded from a 5   km wide passage between two palaeo‐islands into a perpendicular, 10 to 15   km wide strait between the palaeo‐islands at one side and Sicily at the other during the Emilian highstand (1·6   Ma to 1·1   Ma). The clinoformed carbonate wedge, which is 50   m thick and 6   km long, formed by east/south‐east progradation of a platform on the submarine sill by currents that were funnelled between the two palaeo‐islands. Platform‐slope clinoforms evolved from initial aggradation (thin and low‐angle) into a progradation phase (thick and high‐angle). Both clinoform types are characterized by a bimodal facies stacking pattern defined by sedimentary structures created by: (i) subaqueous dunes associated with dilute subcritical currents; and (ii) upper‐flow‐regime bedforms associated with sediment‐laden supercritical turbidity currents. Focusing of episodic currents on the platform by funnelling between the islands controlled the downstream formation of a sediment body, here named carbonate delta. The carbonate delta interfingers with subaqueous dune deposits formed in the perpendicular strait. This study uses a reconstruction of bedform dynamics to unravel the evolution of this gateway‐related carbonate accumulation.     

Land subsidence along the Ionian coast of SE Sicily (Italy), detection and analysis via Small Baseline Subset (SBAS) multitemporal differential SAR interferometry

The paper presents the results of a multi‐temporal, differential interferometric synthetic aperture radar (DInSAR) analysis aiming to identify active surface deformation phenomena in south‐eastern Sicily. The study area has been chosen because of its strong seismicity, high concentration of industrial and agricultural activities, and high density of people living in the coastal area. Furthermore, the morphology, lithology and climatic features of this sector of the Hyblean foreland are suitable for an interferometric analysis, providing a high coherence over the area. The Small BAseline Subset (SBAS) multitemporal DInSAR technique was used to calculate mean ground velocity maps and displacement time series from a large data set of European Remote Sensing Satellites (ERS 1–2) images spanning the time period 1992–2000. The reliability of the DInSAR results was tested calculating the East_SAR and Up_SAR values over two permanent global positioning system (GPS) stations in the area, and comparing them with the East_GPS and Up_GPS values. The residuals between GPS and DInSAR velocities were 1 and 0.6 mm/yr for the Up and East components, respectively. Four main subsiding areas, previously undetected, have been identified, corresponding with the towns of Augusta, Siracusa, Priolo, and Villasmundo. The observed deformation phenomena are located within coastal structural basins, filled with Pleistocene and Holocence deposits, except the Villasmundo land subsidence, which is located on the Hyblean plateau. The measured deformation rates reach values up to ?18 mm/yr in Augusta, –6 mm/yr in Siracusa, –5 mm/yr in Villasmundo and ?4.5 mm/yr in Priolo. The examination of velocity profiles, time series, and geological data allows us to relate all the detected deformation patterns primarily to groundwater over‐exploitation. A multi‐dimensional interpolation with kriging was performed to obtain a field subsidence map. A first‐order elastic deformation model was used to simulate the peculiar features of the Villasmundo subsidence. Copyright © 2011 John Wiley & Sons, Ltd.     

Growth discontinuity in males of the deep-water giant red shrimp Aristaeomorpha foliacea in the Mediterranean Sea

The deep-water giant red shrimp, Aristaeomorpha foliacea (Risso, 1827) (Decapoda, Aristeidae), represents a highly valuable resource for bottom trawling in the Mediterranean Sea. Recent assessments have described both a worsening of the status of the traditionally exploited stocks and low levels of annual-based instantaneous natural mortality (M 0.4–0.7 year⁻¹) in the unexploited stocks. The mortality (M) figures, however, are in contrast with the longevity (T_max) of 3–4-year males and 4–5-year females, estimated from classical length frequency distribution analysis. Reduced growth (after the onset of sexual maturity) and pile-up of older individuals in the larger size classes have been considered to be reasonable explanations for the contrast between M and T_max. We propose that a discontinuity of the growth models could address this contrast. Because a clear discontinuity in sexual maturity is evident only in males, length frequency distribution data for different sets of males collected from the South of Sicily and the Maltese Islands deep bottoms (400–800 m) were fitted with both the classic (c) and double-phased (d) von Bertalanffy growth formula (VBGF). According to the dVBGF, adult males sharply reduce their growth rate after reaching an age between 1.2 and 1.5 year, which corresponds to the estimates of age at sexual maturity (t_m between 1 and 1.5 years). The reduction in growth determines a higher T_max (7.3–9.5 year) and lower M (0.4–0.6 year⁻¹) than previously derived on the basis of cVBGF estimates (T_max 3–4 years and M 1.2 year⁻¹). The dVBGF results suggest that sexual dimorphism and length–sex segregation in giant red shrimps reflect an alternative life history strategy that is based mainly on growth reduction in adult males and it might be adopted for implementing more conservative assessments.     

Organochlorine compounds in tissues of swordfish (Xiphias gladius) from Mediterranean Sea and Azores islands

Polychlorobiphenyls (PCB) and organochlorine (OC) pesticides are endocrine-disrupting chemicals (EDCs). The Italian Ministry of Environment has undertaken a program (1999-2001) to measure levels of contaminants in top marine predators and to develop sensitive biomarkers for the evaluation of toxicological risk in these species. In 1999, 15 swordfishes (Xiphias gladius) taken from the Mediterranean Sea along the Sicilian coast (Strait of Messina, Italy) and in the Atlantic Ocean along the Azores Islands, and analysed for 34 congeners of PCBs and 27 organochlorine (OC) pesticides in gonad, muscle, liver and blubber tissues. In the tissues of Mediterranean swordfishes the sum of the determined PCBs congeners ranged from 4.61 to 4651.17 ng g(-1) on fresh tissue basis. Among organochlorine pesticides DDE, DDT and DDD (TDE) predominated with an overall range of 2.37-4734.56 ng(-1) w.w. In particular p,p'-DDE had concentrations appearing up to 3900 ng(-1), with the highest values found in fatty tissues, such as blubber. In the liver of Azores Island swordfishes lower levels of summation PCBs (8.43-294.17 ng/g w.w.) and summation DDTs (<0.01-217.44 ng/g w.w.) were determined.