A computer program for calculation and plotting of stress distribution and faulting     

Sandro Serra 《Mathematical Geology》1973,5(4):397-407

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Petrology and geochemistry of potassic and ultrapotassic volcanism in central Italy: petrogenesis and inferences on the evolution of the mantle sources   总被引：15，自引：0，他引：15  

Sandro Conticelli  Angelo Peccerillo 《Lithos》1992,28(3-6):221-240

Major, trace element, Sr isotopic and mineral chemical data are reported for mafic volcanic rocks (Mg-value 65) from the northern-central sector of the potassic volcanic belt of Central Italy. The rocks investigated range from potassic series (KS) and high-K series (HKS) to lamproitic (LMP) and kamafugitic (KAM) through a transitional series (TRANS), thus covering the entire compositional spectrum of potassic and ultrapotassic magmas. KAM rocks are strongly silica undersaturated and, compared with the other rock series, have low SiO₂, Al₂O₃, Na₂O, Sc and V and high CaO, K/Na, (Na + K)/Al. KS and HKS have high Al₂O₃, CaO and variable enrichment in K₂O and incompatible elements. LMP rocks are saturated in silica and have high SiO₂, K₂O, K₂O/Na₂, MgO, Ni and Cr and low Al₂O₃, CaO, Na₂O, Sc and V. TRANS rocks display intermediate compositional characteristics between LMP and KS.

All the rocks under study have fractionated hygromagmaphile element patterns with high LIL/HFS element values and negative anomalies of Ti, Ta, Nb and Ba. Negative Sr anomalies are observed in the LMP and TRANS rocks. LIL elements show overall positive correlations with K₂O, whereas different trends of Sr and HFSE vs. K₂O are defined by LMP-TRANS and KS-HKS-KAM. ⁸⁷Sr/⁸⁶Sr range from about 0.710 to 0.716. KS, HKS and KAM rocks have similar ⁸⁷Sr/⁸⁶Sr values clustering around 0.710. LMP and TRANS rocks have the highest ⁸⁷Sr/⁸⁶Sr values.

Geochemical and isotopic data reported for the most primitive Italian potassic and ultrapotassic rocks support the hypothesis that the interaction between crustal and mantle reservoirs was a main process in the genesis of Italian potassic magmatism. Simple mass balance calculations exclude, however, an important role of crustal assimilation during ascent of subcrustal magmas to the surface and indicate that the sources of Central Italy volcanics underwent contamination with fluids and/or melts released by upper crustal material previously brought into the mantle by subduction processes.

Different trends of incompatible elements vs. K₂O observed in the studied rocks suggest distinct metasomatic processes for the sources of the investigated magmas. Liquids derived by bulk melting of pelitic sediments are believed to be the most likely contaminants of the source of LMP rocks. Fluids or melts rich in Ca, Sr and with high LILE/HFSE value and Sr isotopic composition around 0.710 are the most likely contaminant of the source region of KS, HKS and KAM volcanics. Variations in CaO, Na₂O and ferromagnesian element abundances and ratios suggest that, in some zones, the mantle source of potassic magmas experienced partial melting with extraction of basaltic liquids prior to metasomatism.  相似文献   

Heavy metal contamination in surface sediments from the Gulf of Venice, Italy     

Romano Donazzolo  Oplinia Hieke Merlin  Laura Menegazzo Vitturi  Angelo A. Orio  Bruno Pavoni  Guido Perin  Sandro Rabitti 《Marine pollution bulletin》1981,12(12):417-425

The authors studied surface sediments from 102 stations in four areas of the three port entrances to the Lagoon of Venice, examining the relationships between textural character, mineralogical composition, and Hg, Pb, Cd, Cu, Ni, Cr, Zn, Co and Fe content. Heavy metal distribution allowed boundaries to be fixed between polluted and nonpolluted zones. While the Cavallino area is not polluted, very high concentrations of Zn, Pb and Hg in the two central areas, facing the Lido and Malamocco port entrances, respectively, suggest that wastes mainly from industrial production of zinc are present. High concentrations of Cr in the southern part of the Chioggia area are probably due to tannery wastes reaching the sea from the Brenta river.  相似文献   

Petrological significance of high-pressure ultramafic xenoliths from ultrapotassic rocks of Central Italy     

Sandro Conticelli  Angelo Peccerillo 《Lithos》1989,24(4):305-322

Two suites of ultramafic xenoliths have been found in ultrapotassic lavas from the 0.9 Ma old Torre Alfina volcano sited at the northern border of the Vulsinian district (Central Italy). One group of Xenoliths consists of spinel-bearing lherzolites, harzburgites, minor wherlites and dunites with a maximum size of 3–4 cm. Some samples contain discrete laths of phlogopite. A second class consists of phlogopite-rich, glass-bearing peridotites. The first suite displays textural characteristics such as triple points, deformed olivine with well developed kink banding and porphyroclastic textures indicating equilibration at high pressure. Pressure estimates give values in the range 1.3–2.5 GPa, corresponding to mantle depths in the area, where the present-day Moho is about 25 km deep. Equilibration temperatures have been estimated in the range between 950–1000°C. The chemical composition of some phases, such as the very high Fo contents of olivines (up to Fo₉₄ in harzburgites), Mg content of orthopyroxenes and Cr/Cr+Al ratios of clinopyroxenes and spinels, suggest that these xenoliths represent peridotites which suffered different degrees of partial melting before being incorporated into the Torre Alfina magma. On the other hand, the occurrence of phlogopite speaks for metasomatic events. The phlogopite-rich, glass-bearing xenoliths consist of phlogopite, olivine, clinopyroxene, rare orthopyroxene and glass. Apatite is the most common accessory. Olivine is present in both euhedral and strained crystals. A few relics of protogranular textures are also observed. Textural and chemical evidence suggests that these xenoliths represent mica-rich peridotites which have undergone phlogopite breakdown during rapid rise to the surface with the development of a K-rich liquid which reacted with mafic phases producing a rapid growth of olivine and, to a lower extent, pyroxene. Originally, these xenoliths may have represented intensively metasomatized upper mantle. However, a cumulitic origin from previous potassic magmatic events cannot be excluded. The host lavas have compositions intermediate between high-silica lamproite and Roman-type ultrapotassic rock. They have high abundances of incompatible elements and radiogenic Sr, coupled with high Mg content, MgO/CaO, Ni and Cr. These features support a genesis in a residual upper mantle which has suffered partial melting with the extraction of basaltic liquids, followed by metasomatic events which caused an enrichment in incompatible elements and radiogenic Sr. The presence of mantle-derived ultramafic xenoliths in the torre Alfina lavas testifies for a rapid uprise of the magma which reached the surface without suffering fractional crystallization and significant interaction with the upper crust. Accordingly, the Torre Alfina lavas represent an unique example of primitive potassic liquid in Central Italy.  相似文献   

Wet deposition due to fog in the Po Valley,Italy     

Sandro Fuzzi  Giordano Orsi  Mauro Mariotti 《Journal of Atmospheric Chemistry》1985,3(2):289-296

Wet deposition due to radiation fog is examined in this paper. The area where the reported measurements were performed, the Po Valley, northern Italy, is characterized by both a high fog occurrence during the fall-winter months and fog water solutions of high ionic concentration and acidity.Estimated wet deposition for NH ₄ ⁺ , NO _inf3 ^sup- and SO _inf4 ^sup2- ions due to fog droplet settling to the ground accounts for 13.2, 12.1 and 5.3 percent with respect to bulk precipitations over the same period: January–March and October–December (fog season).Fog deposition rates show that this process can be an important pathway of trace gases and particles loss from the air. First indicative results of fog removal efficiency with respect to air particulate matter are presented.Dry deposition parameters should be taken into account in evaluating the potential effect of fog droplet deposition on vegetation.  相似文献   

Using GB-SAR technique to monitor slow moving landslide   总被引：3，自引：0，他引：3  

Linhsia Noferini  Massimiliano Pieraccini  Daniele Mecatti  Giovanni Macaluso  Carlo Atzeni  Matteo Mantovani  Gianluca Marcato  Alessandro Pasuto  Sandro Silvano  Fabrizio Tagliavini 《Engineering Geology》2007,95(3-4):88-98

A Ground-Based SAR (GB-SAR) interferometer was employed to measure the surface displacements of a landslide occurring in the Carnian Alps, north-eastern Italy, which has affected a national road and seriously damaged a road tunnel still under construction. Moreover, since the landslide is located on the left bank of the Tagliamento River Valley, it is feared that this mass movement might dam the river, creating a basin that would increase natural hazard for the valley inhabitants. The data collected from December 2002 to July 2005 by a conventional monitoring system, consisting of a GPS network and boreholes equipped with inclinometric tubes, showed that the landslide was moving at a quasi-constant rate of about 3 cm per year. Due to the slow deformation rate of the landslide, a recently developed GB-SAR technique based on the analysis of a restricted ensemble of coherent points was used. Two surveys, each lasting two days, were planned in December 2004 and July 2005, in order to map and measure the surface displacements that occurred over time. The results from the radar were compared with the ones derived from the GPS monitoring network. An agreement was achieved among the data collected, showing the capability of the GB-SAR technique to measure displacements even within a time span of several months between the surveys.  相似文献   

Intercomparison of the northern hemisphere winter mid-latitude atmospheric variability of the IPCC models     

Valerio Lucarini  Sandro Calmanti  Alessandro Dell’Aquila  Paolo M. Ruti  Antonio Speranza 《Climate Dynamics》2007,28(7-8):829-848

We compare, for the overlapping time frame 1962–2000, the estimate of the northern hemisphere mid-latitude winter atmospheric variability within the available 20th century simulations of 19 global climate models included in the Intergovernmental Panel on Climate Change—4th Assessment Report with the NCEP-NCAR and ECMWF reanalyses. We compute the Hayashi spectra of the 500 hPa geopotential height fields and introduce an ad hoc integral measure of the variability observed in the Northern Hemisphere on different spectral sub-domains. The total wave variability is taken as a global scalar metric describing the overall performance of each model, while the total variability pertaining to the eastward propagating baroclinic waves and to the planetary waves are taken as scalar metrics describing the performance of each model phenomenologically in connection with the corresponding specific physical process. Only two very high-resolution global climate models have a good agreement with reanalyses for both the global and the process-oriented metrics. Large biases, in several cases larger than 20%, are found in all the considered metrics between the wave climatologies of most IPCC models and the reanalyses, while the span of the climatologies of the various models is, in all cases, around 50%. In particular, the travelling baroclinic waves are typically overestimated by the climate models, while the planetary waves are usually underestimated, in agreement with what found is past analyses performed on global weather forecasting models. When comparing the results of similar models, it is apparent that in some cases the vertical resolution of the model atmosphere, the adopted ocean model, and the advection schemes seem to be critical in the bulk of the atmospheric variability. The models ensemble obtained by arithmetic averaging of the results of all models is biased with respect to the reanalyses but is comparable to the best five models. Nevertheless, the models results do not cluster around their ensemble mean. This study suggests caveats with respect to the ability of most of the presently available climate models in representing the statistical properties of the global scale atmospheric dynamics of the present climate and, a fortiori, in the perspective of modeling climate change.  相似文献   

Multitemporal UAV surveys for landslide mapping and characterization   总被引：1，自引：0，他引：1  

Guglielmo Rossi  Luca Tanteri  Veronica Tofani  Pietro Vannocci  Sandro Moretti  Nicola Casagli 《Landslides》2018,15(5):1045-1052

This paper presents the preliminary results of the IPL project 196 “Development and applications of a multi-sensor drone for geohazards monitoring and mapping.” The objective of the project is to test the applicability of a multi-sensor drone for the mapping and monitoring of different types of geohazards. The Department of Earth Sciences of the University of Florence has developed a new type of drone airframe. Several survey campaigns were performed in the village of Ricasoli, in the Upper Arno river Valley (Tuscany, Italy) with the drone equipped with an optical camera to understand the possibility of this rising technology to map and characterize landslides. The aerial images were combined and analyzed using Structure-from-Motion (SfM) software. The collected data allowed an accurate reconstruction and mapping of the detected landslides. Comparative analysis of the obtained DTMs also permitted the detection of some slope portions being prone to failure and to evaluate the area and volume of the involved mass.  相似文献   

Integration of rainfall thresholds and susceptibility maps in the Emilia Romagna (Italy) regional-scale landslide warning system   总被引：2，自引：2，他引：0  

Samuele Segoni  Daniela Lagomarsino  Riccardo Fanti  Sandro Moretti  Nicola Casagli 《Landslides》2015,12(4):773-785

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Fe<Superscript>3+</Superscript> reduction during biotite melting in graphitic metapelites: another origin of CO<Subscript>2</Subscript> in granulites     

Bernardo?CesareEmail author  Sandro?Meli  Luca?Nodari  Umberto?Russo 《Contributions to Mineralogy and Petrology》2005,149(2):129-140

The Fe³⁺/Fe_tot of all Fe-bearing minerals has been analysed by Mössbauer spectroscopy in a suite of biotite-rich to biotite-free graphitic metapelite xenoliths, proxies of an amphibolite-granulite transition through progressive biotite melting. Biotite contains 9 to 16% Fe³⁺/Fe_tot, whereas garnet, cordierite and ilmenite are virtually Fe³⁺ -free (0–1% Fe³⁺/Fe_tot) in all samples, regardless of biotite presence. Under relatively reducing conditions (graphite-bearing assemblages), biotite is the only carrier of Fe³⁺ during high-temperature metamorphism; therefore, its disappearance by melting represents an important event of iron reduction during granulite formation, because haplogranitic melts usually incorporate small amounts of ferric iron. Iron reduction is accompanied by the oxidation of carbon and the production of CO₂, according to the redox reaction: Depending on the nature of the peritectic Fe-Mg mineral produced (garnet, cordierite, orthopyroxene), the CO₂ can either be present as a free fluid component, or be completely stored within melt and cordierite. The oxidation of graphite by iron reduction can account for the in situ generation of CO₂, implying a consequential rather than causal role of CO₂ in some granulites and migmatites. This genetic model is relevant to graphitic rocks more generally and may explain why CO₂ is present in some granulites although it is not required for their formation.  相似文献