The Central-Western Mediterranean: Anomalous igneous activity in an anomalous collisional tectonic setting     

Michele Lustrino  Svend Duggen  Claudio L. Rosenberg 《Earth》2011,104(1-3):1-40

The central-western Mediterranean area is a key region for understanding the complex interaction between igneous activity and tectonics. In this review, the specific geochemical character of several ‘subduction-related’ Cenozoic igneous provinces are described with a view to identifying the processes responsible for the modifications of their sources. Different petrogenetic models are reviewed in the light of competing geological and geodynamic scenarios proposed in the literature.Plutonic rocks occur almost exclusively in the Eocene–Oligocene Periadriatic Province of the Alps while relatively minor plutonic bodies (mostly Miocene in age) crop out in N Morocco, S Spain and N Algeria. Igneous activity is otherwise confined to lava flows and dykes accompanied by relatively greater volumes of pyroclastic (often ignimbritic) products. Overall, the igneous activity spanned a wide temporal range, from middle Eocene (such as the Periadriatic Province) to the present (as in the Neapolitan of southern Italy). The magmatic products are mostly SiO₂-oversaturated, showing calcalkaline to high-K calcalcaline affinity, except in some areas (as in peninsular Italy) where potassic to ultrapotassic compositions prevail. The ultrapotassic magmas (which include leucitites to leucite-phonolites) are dominantly SiO₂-undersaturated, although rare, SiO₂-saturated (i.e., leucite-free lamproites) appear over much of this region, examples being in the Betics (southeast Spain), the northwest Alps, northeast Corsica (France), Tuscany (northwest Italy), southeast Tyrrhenian Sea (Cornacya Seamount) and possibly in the Tell region (northeast Algeria).Excepted for the Alpine case, subduction-related igneous activity is strictly linked to the formation of the Mediterranean Sea. This Sea, at least in its central and western sectors, is made up of several young (< 30 Ma) V-shaped back-arc basins plus several dispersed continental fragments, originally in crustal continuity with the European plate (Sardinia, Corsica, Balearic Islands, Kabylies, Calabria, Peloritani Mountains). The bulk of igneous activity in the central-western Mediterranean is believed to have tapped mantle ‘wedge’ regions, metasomatized by pressure-related dehydration of the subducting slabs. The presence of subduction-related igneous rocks with a wide range of chemical composition has been related to the interplay of several factors among which the pre-metasomatic composition of the mantle wedges (i.e., fertile vs. refractory mineralogy), the composition of the subducting plate (i.e., the type and amount of sediment cover and the alteration state of the crust), the variable thermo-baric conditions of magma formation, coupled with variable molar concentrations of CO₂ and H₂O in the fluid phase released by the subducting plates are the most important.Compared to classic collisional settings (e.g., Himalayas), the central-western Mediterranean area shows a range of unusual geological and magmatological features. These include: a) the rapid formation of extensional basins in an overall compressional setting related to Africa-Europe convergence; b) centrifugal wave of both compressive and extensional tectonics starting from a ‘pivotal’ region around the Gulf of Lyon; c) the development of concomitant Cenozoic subduction zones with different subduction and tectonic transport directions; d) subduction ‘inversion’ events (e.g., currently along the Maghrebian coast and in northern Sicily, previously at the southern paleo-European margin); e) a repeated temporal pattern whereby subduction-related magmatic activity gives way to magmas of intraplate geochemical type; f) the late-stage appearance of magmas with collision-related ‘exotic’ (potassic to ultrapotassic) compositions, generally absent from simple subduction settings; g) the relative scarcity of typical calcalkaline magmas along the Italian peninsula; h) the absence of igneous activity where it might well be expected (e.g., above the hanging-wall of the Late Cretaceous–Eocene Adria–Europe subduction system in the Alps); i) voluminous production of subduction-related magmas coeval with extensional tectonic régimes (e.g., during Oligo-Miocene Sardinian Trough formation).To summarize, these salient central-western Mediterranean features, characterizing a late-stage of the classic ‘Wilson Cycle’ offer a ‘template’ for interpreting magmatic compositions in analogous settings elsewhere.  相似文献   

Applicability of solid state fast field cycling NMR relaxometry in understanding relaxation properties of leaves and leaf-litters     

Anne E. BernsSalvatore Bubici  Claudio De PasqualeGiuseppe Alonzo  Pellegrino Conte 《Organic Geochemistry》2011,42(8):978-984

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The Second World Landslide Forum     

Claudio Margottini  Paolo Canuti  Kyoji Sassa 《Landslides》2011,8(1):133-138

ICL\IPL Activities

The Second World Landslide Forum  相似文献   

From back-analysis to run-out prediction: a case study in the Western Italian Alps   总被引：3，自引：1，他引：2  

Marina Pirulli  Alessio Colombo  Claudio Scavia 《Landslides》2011,8(2):159-170

Rock avalanches are complex phenomena that occur with a low frequency but which have a high destructive potential. As a consequence, the people who are responsible for the management of a territory are more and more interested in predicting the possible evolutions of well-known potential events. Tackling the above problems from a quantitative point of view, the RASH3D code, based on continuum mechanics concepts, has been here used to predict the evolution of a potential rock avalanche in the Western Italian Alps. A calibration-based approach, in which rheological parameters are constrained by systematic adjustment during trial-and-error back-analysis of past events similar to the landslide under investigation, is proposed to set rheological parameter values to be used for prediction purposes. The back-analysis of a 2?10⁶ m³ rock avalanche located in the Divedro Valley, close to the area of the potential event, has then been analysed using both a frictional and a Voellmy rheology. The characteristics of the slope and the dynamics of the event have made the frictional rheology more suitable to come to the correct simulation of the historical case. The back-analysis results have contributed not only in the selection of the rheological parameter values but also in the choice of the type of rheological law to use in the carried out forward-analyses.  相似文献   

The Tauern Window (Eastern Alps, Austria): a new tectonic map, with cross-sections and a tectonometamorphic synthesis     

Stefan M. Schmid  Andreas Scharf  Mark R. Handy  Claudio L. Rosenberg 《Swiss Journal of Geoscience》2013,106(1):1-32

We present a tectonic map of the Tauern Window and surrounding units (Eastern Alps, Austria), combined with a series of crustal-scale cross-sections parallel and perpendicular to the Alpine orogen. This compilation, largely based on literature data and completed by own investigations, reveals that the present-day structure of the Tauern Window is primarily characterized by a crustal-scale duplex, the Venediger Duplex (Venediger Nappe system), formed during the Oligocene, and overprinted by doming and lateral extrusion during the Miocene. This severe Miocene overprint was most probably triggered by the indentation of the Southalpine Units east of the Giudicarie Belt, initiating at 23–21 Ma and linked to a lithosphere-scale reorganization of the geometry of mantle slabs. A kinematic reconstruction shows that accretion of European lithosphere and oceanic domains to the Adriatic (Austroalpine) upper plate, accompanied by high-pressure overprint of some of the units of the Tauern Window, has a long history, starting in Turonian time (around 90 Ma) and culminating in Lutetian to Bartonian time (45–37 Ma).  相似文献   

Organochlorine compounds in sharks from the Brazilian coast     

Claudio Eduardo de Azevedo e Silva  Adriana de Cássia Lima Dias  José Lailson-Brito  Jean Remy Daveé Guimarães 《Marine pollution bulletin》2009,58(2):294-298

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Interactive effects of environmental variability and human impacts on the long-term dynamics of an Amazonian floodplain lake and a South Atlantic coastal lagoon   总被引：2，自引：1，他引：1  

Reinaldo L. Bozelli  Adriano Caliman  Rafael D. Guariento  Luciana S. Carneiro  Jayme M. Santangelo  Marcos P. Figueiredo-Barros  Joo J.F. Leal  Adriana M. Rocha  Letícia B. Quesado  Paloma M. Lopes  Vinicius F. Farjalla  Claudio C. Marinho  Fabio Roland  Francisco A. Esteves 《Limnologica》2009,39(4):306-313

Human activities are exposing freshwater ecosystems to a wide range of stressors, whose direct and indirect effects can be alleviated or exacerbated through interactive effects with dynamic environmental drivers. This study used long-term data from two Neotropical lacustrine freshwater systems (Batata Lake, an Amazonian floodplain lake and Imboassica lagoon, an Atlantic coastal lagoon) subjected to different kinds of environmental fluctuations (i.e., flood pulse and sandbar opening) and anthropogenic impacts (i.e., siltation and eutrophication). Our objective was to determine whether the effects of human perturbations are contingent on modifications of important biotic and abiotic characteristics through environmental variability. For both ecosystems, environmental variability consistently interacted with anthropogenic perturbations to alter most of the variables analyzed, such as nutrient dynamics, chlorophyll-a concentration, zooplankton and benthic invertebrate species richness, and temporal community stability, which indicates that interactive effects between environmental variability and anthropogenic perturbations may impact a myriad of ecosystem properties. Furthermore, the nature of these interactive effects was highly dependent on the variable considered and on the ecosystem analyzed. For example, at Imboassica lagoon, sandbar openings interacted synergistically with trophic state to increase the phosphorus concentration in the water column. At Batata Lake, flooding generally alleviated the negative effects of siltation on species richness by both diluting inorganic suspended material concentration and by promoting local recruitment from the regional species pool. Such results indicate that our ability to understand and predict the outcome of anthropogenic impacts on inland aquatic systems can be hampered if we consider human stressors as “static” phenomena disconnected from dynamic interactions with major local environmental drivers.  相似文献   

Estimation of load reduction factors for clay masonry walls     

Francesca da Porto  Manuel Grendene  Claudio Modena 《地震工程与结构动力学》2009,38(10):1155-1174

The in‐plane cyclic behaviour of three types of unreinforced clay masonry was characterized by means of laboratory tests on full‐scale specimens. The masonry walls were assembled with various bonding arrangements (head joints made with mortar pockets, dry head joints with mechanical interlocking, thin‐layer mortar bed joints), which are not yet inserted in seismic codes. Experimental behaviour was modelled with an analytical hysteretic model able to predict lateral load–displacement curves in case of shear failure of the unreinforced walls. According to the experimental results and those of the selected analytical model, parametric study to evaluate the reduction in lateral strength demand produced by non‐linear behaviour in masonry walls, i.e. the load reduction factor was carried out by non‐linear dynamic analyses. The calculated values of the load reduction factor were modest. The differences in values found for the three masonry types, although consistent with them, were not great. This may indicate that, in the ultimate limit state, the type of masonry cannot significantly affect the behaviour of an entire building. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Environmental conditions for gravelly and pebbly dunes and sorted bedforms on a moderate-energy inner shelf (Marettimo Island,Italy, western Mediterranean)     

Claudio Lo Iacono  Jorge Guillén 《Continental Shelf Research》2008

Side scan sonar records, sediment textural characteristics, and in-situ field observations were used to study gravelly and pebbly dunes and sorted bedforms on the inner shelf of Marettimo Island, along the northwestern Sicilian shelf. The dunes are composed of coarse sands, gravels and pebbles (D50: 2–16 mm), displaying a symmetrical shape with a wavelength in the range of 1–2.5 m and a height of 0.15–0.30 m. The bedforms are distributed in a patchy pattern in a depth range of 10–50 m, and are described for the first time on a Mediterranean inner shelf. Sorted bedforms are linear morphological features developed almost perpendicular to the coast in the eastern sector of the island between 15 and 50 m water depth. Bottom shear stresses required for sediment entrainment and the generation of the shallower dunes can be reached during strong storms (Hs=5–6 m; Tp=9–11 s), which are not common in the Mediterranean Sea. However, wave storm events recorded in the study area during the last 17 years are not able to generate the coarsest and deeper dunes, suggesting that the stirring mechanism for dune formation is associated with severe storms that have a recurrence interval of more than 17 years. The long-term stability of the coarse bedforms is supported by the permanence of sorted bedforms without significant morphological changes for long periods (>13 years). Therefore, it is shown that processes forming coarse bedforms can occur in tideless and moderate-energy settings like those of the Mediterranean continental shelves, although the morphological features are probably less dynamic and remain unaltered for longer periods than on higher-energy shelves.  相似文献   

Genesis of zeolites in the Neapolitan Yellow Tuff: geological, volcanological and mineralogical evidence   总被引：1，自引：1，他引：0  

Maurizio de'Gennaro  Piergiulio Cappelletti  Alessio Langella  Annamaria Perrotta  Claudio Scarpati 《Contributions to Mineralogy and Petrology》2000,139(1):17-35

 The study proposes a model by which a thick succession of volcanic tuffs can be zeolitized by alteration of pyroclastic material in the presence of sufficient eruptive water and at temperatures close to water vapour condensation. In the case of phreatomagmatic products, the model simplifies interpretation of problematic deposits that exhibit pronounced vertical and lateral variation in lithification grade. A major feature of the model is that thick zeolitized tuffs can be formed during emplacement of pyroclastic products, in marked contrast to later alteration in an open hydrologic system. Geological, volcanological and mineralogical data for the Neapolitan Yellow Tuff, a widespread trachytic pyroclastic deposit outcropping around Campi Flegrei (Southern Italy), have been used to infer the physico-chemical conditions that determined mineral genesis. This tuff shows a reduction in lithification grade towards the base, top and with distance from the vent and very variable zeolitization within the lithified portion. We suggest that during initial emplacement the erupted products chilled against the ground, inhibiting zeolite crystallization. During rapid deposition of the thick, wet succession thermal insulation allowed the persistence of elevated temperatures for a time sufficient for enhancement of hydration-dissolution processes in the volcanic glass. The highly reactive alkali-trachytic glass quickly buffered the acid pH of the system, favouring phillipsite crystallization followed by chabazite nucleation. The variable zeolite content reflects fluctuating emplacement conditions (e.g. changes in water content and temperature). Cooling of the upper and relatively thin distal deposits inhibited the zeolitization process, thereby preserving the primary unlithified deposit. Received: 25 May 1999 / Accepted: 28 October 1999  相似文献