Intercomparison of Boron Isotope and Concentration Measurements. Part II: Evaluation of Results   总被引：3，自引：1，他引：3  

Roberto Gonfiantini  Sonia Tonarini  Manfred Grning  Alessandra Adorni‐Braccesi  Assad S. Al‐Ammar  Marcus Astner  Sebastien Bchler  Ramon M. Barnes  Randy L. Bassett  Alain Cocherie  Annette Deyhle  Andrea Dini  Giorgio Ferrara  Jrme Gaillardet  Judith Grimm  Catherine Guerrot  Urs Krhenbühl  Graham Layne  Damien Lemarchand  Anette Meixner  D. Jack Northington  Maddalena Pennisi  Eva Reitznerov  Ilia Rodushkin  Naoji Sugiura  Regina Surberg  Sabine Tonn  Michael Wiedenbeck  Samuel Wunderli  Yingkai Xiao  Thomas Zack 《Geostandards and Geoanalytical Research》2003,27(1):41-57

The Istituto di Geoscienze e Georisorse (IGG), on behalf and with the support of the International Atomic Energy Agency (IAEA), prepared eight geological materials (three natural waters and five rocks and minerals), intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials were distributed to twenty seven laboratories - virtually all those performing geochemical boron isotope analyses in the world -which agreed to participate in the intercomparison exercise. Only fifteen laboratories, however, ultimately submitted the isotopic and/or concentration results they obtained on the intercomparison materials. The results demonstrate that interlaboratory reproducibility is not well reflected by the precision values reported by the individual laboratories and this observation holds true for both boron concentration and isotopic composition. The reasons for the discrepancies include fractionations due to the chemical matrix of materials, relative shift of the zero position on the δ¹¹B scale and a lack of well characterized materials for calibrating absolute boron content measurements. The intercomparison materials are now available at the IAEA (solid materials) and IGG (waters) for future distribution.  相似文献   

Effect of degassing on sulfur contents and δ34S values in Somma-Vesuvius magmas     

Luigi Marini  Valeria Chiappini  Roberto Cioni  G. Cortecci  E. Dinelli  Claudia Principe  Giorgio Ferrara 《Bulletin of Volcanology》1998,60(3):187-194

Sulfur contents and δ³⁴S values of Somma-Vesuvius magmas are consistent with syneruptive, open-system degassing at temperatures of 800–850°C for Plinian pumices and 1100–1200°C for lavas. The extent of degassing appears to be greater in lavas than in pumices. The key parameter controlling the ³⁴S/³²S ratio of Somma-Vesuvius volcanics is the average magma oxidation state, which generally varies from 0.85 to 1.20 Δ NNO units for lavas and from 1.20 to 1.40 Δ NNO units for pumices. Consequently, S contents and δ³⁴S values of magmas constitute a potentially valuable tool in estimating their average redox conditions. The results of this study may help in risk mitigation when the Vesuvius magmatic system evolves toward eruptive conditions. Received: 20 January 1998 / Accepted: 5 May 1998  相似文献   

Observations of Atmospheric Solitary Waves in the Urban Boundary Layer     

M. P. Rao  Paolo Castracane  Stefano Casadio  Daniele Fuá  Giorgio Fiocco 《Boundary-Layer Meteorology》2004,111(1):85-108

The simultaneous operation of a three-axis Doppler sodar system in the centralurban area of Rome and two similar systems in the suburban area, forming atriangle about 20 km on each side, provided evidence of solitary-type wavesin the urban boundary layer. Three events, each lasting from a few minutes toabout 30 min, and ranging in depth from the minimum range of the sodar (39 m) to over 500 m, are reported here. Two events were recognizable onall three sodar records while the third event could be observed at the urbanlocation only. Time-height acoustic echo intensity records showed no-echoregions within the wave indicating transport of trapped recirculating air.This is typical of large amplitude solitary waves. The time series plots ofsodar-derived vertical wind velocity revealed a maximum peak-to-peakvariation of about 5 m s^-1 during periods of wave-associated disturbance.The vertical velocity is found to increase with height up to the top of the closedcirculation within the wave and decreases further above. The normalisedamplitude-wavelength relationship for the two events indicates that theobserved waves are close to a strongly nonlinear regime.  相似文献   

Seven landslide dams of old seismic origin in southeastern Sicily (Italy)   总被引：3，自引：0，他引：3  

Pier Giorgio Nicoletti  Mario Parise   《Geomorphology》2002,46(3-4)

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.  相似文献   

Quincentenary of the discovery of the americas     

Giorgio Doria  Adalberto Vallega 《GeoJournal》1992,26(4):435-436

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Ricerche eseguite nelle cave di calcare di Monte Rombolo per rintracciare fori di sonda     

Dott. Giorgio Melchiori 《Pure and Applied Geophysics》1944,6(1-2):76-87

Riassunto Vengono esposti i criteri seguiti per determinare con metodi acustici e magnetometrici la direzione dei fori di sonda quando si presenta la necessità di ricercarli ad un determinato livello e quando si teme che le indicazioni topografiche non siano sufficienti alla loro determinazione causa la deviazione frequente che questi fori hanno dalla verticale.

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Zusammenfassung Man erörtet die Verfahren die verfolgt würden um mit akustischen und magnetometrischen Messungen die Richtung der Rohrlöcher zu bestimmen, wenn die Notwendigkeit besteht ein Bohrloch in einer bestimmten Sole zu erforschern und wenn die topographischen Hinweise nicht genügend zu ihrer Bestimmung sind, infolge der häufigen eintretenden Abweichungen dieser Bohrlöcher von der Vertikale.

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On using Boussinesq-type equations near the shoreline: a note of caution   总被引：1，自引：0，他引：1  

Giorgio Bellotti  Maurizio Brocchini   《Ocean Engineering》2002,29(12):1569-1575

We briefly analyze some characteristics of the behavior in very shallow waters i.e. near the shoreline of high-order (dispersive-nonlinear) Boussinesq-type equations. By using the Carrier and Greenspan (1958) solution as test flow conditions we illustrate the behavior of both purely dispersive and dispersive-nonlinear contributions near the shoreline. It is also shown that Boussinesq-type equations can be more usefully handled in the swash zone if written in terms of the total water depth.  相似文献   

Association between Messinian drainage network formation and major tectonic activity in the Marche Apennines (Italy)     

Sonia Scarselli  Guy D. H. Simpson  Philip A. Allen  Giorgio Minelli  Lorenzo Gaudenzi 《地学学报》2007,19(1):74-81

The Marche Apennines (Italy) offer an excellent opportunity to constrain the temporal and spatial relationships between drainage network formation and tectonic activity. Using a combination of field data, seismic lines and boreholes we show that the main deformation phase took place during the Messinian when the area, affected by the Messinian sea level drop, emerged and evolved from marine to continental conditions. The results highlight that during the Messinian emersion a drainage network developed contemporaneously with an increase in tectonic activity that could be related to sea level fall and river erosion. The present‐day river system, which is dominated by transverse rivers that cut straight across the tectonic grain, is located in older Messinian palaeovalleys, even though the region was subsequently covered by water until the late Pliocene–early Pleistocene.  相似文献   

Hydrogeology of the Nurra Region, Sardinia (Italy): basement-cover influences on groundwater occurrence and hydrogeochemistry   总被引：2，自引：0，他引：2  

Giorgio Ghiglieri  Giacomo Oggiano  Maria Dolores Fidelibus  Tamiru Alemayehu  Giulio Barbieri  Antonio Vernier 《Hydrogeology Journal》2009,17(2):447-466

The Nurra district in the Island of Sardinia (Italy) has a Palaeozoic basement and covers, consisting of Mesozoic carbonates, Cenozoic pyroclastic rocks and Quaternary, mainly clastic, sediments. The faulting and folding affecting the covers predominantly control the geomorphology. The morphology of the southern part is controlled by the Tertiary volcanic activity that generated a stack of pyroclastic flows. Geological structures and lithology exert the main control on recharge and groundwater circulation, as well as its availability and quality. The watershed divides do not fit the groundwater divide; the latter is conditioned by open folds and by faults. The Mesozoic folded carbonate sequences contain appreciable amounts of groundwater, particularly where structural lows are generated by synclines and normal faults. The regional groundwater flow has been defined. The investigated groundwater shows relatively high TDS and chloride concentrations which, along with other hydrogeochemical evidence, rules out sea-water intrusion as the cause of high salinity. The high chloride and sulphate concentrations can be related to deep hydrothermal circuits and to Triassic evaporites, respectively. The source water chemistry has been modified by various geochemical processes due to the groundwater–rock interaction, including ion exchange with hydrothermal minerals and clays, incongruent solution of dolomite, and sulphate reduction.  相似文献   

A new percoid fish from the Eocene of Monte Bolca, Italy: Hendrixella grandei gen. & sp. nov.     

Alexandre F. Bannikov  Giorgio Carnevale 《Swiss Journal of Geoscience》2009,102(3):481-488

A new genus and species of percoid fish, Hendrixella grandei gen. & sp. nov. is described from the upper Ypresian limestone of Monte Bolca, Italy. It is based on four well-preserved specimens that show an elongate and slender body and a unique combination of features, including possession of 11 + 13 vertebrae, two series of intermuscular bones, fused haemal spine of third preural centrum, caudal fin with 17 principal rays and 11 upper and eight lower procurrent rays, predorsal formula 0/0/1 + 1/1/, two separated dorsal fins with rayless pterygiophore in-between, and a single supernumerary spine in both dorsal and anal fins. Due to this unique combination of features, Hendrixella cannot be placed within any existing fossil or extant percoid families and it is placed incertae sedis in the Percoidei. The possession of two series of intermuscular bones represents an unambiguous autapomorphy of Hendrixella. A comparative analysis of the distribution of intermusculars among percomorph fishes indicates that the intermuscular bones of the upper series can be homologized with the epineurals and those of the lower series are the homologs of the epicentrals of non-acanthomorphs.  相似文献