The crystal chemistry of lithium and Fe3+ in synthetic orthopyroxene     

Fernando Cámara  Gianluca Iezzi  Massimo Tiepolo  Roberta Oberti 《Physics and Chemistry of Minerals》2006,33(7):475-483

Lithian ferrian enstatite with Li₂O = 1.39 wt% and Fe₂O₃ 7.54 wt% was synthesised in the (MgO–Li₂O–FeO–SiO₂–H₂O) system at P = 0.3 GPa, T = 1,000°C, fO₂ = +2 Pbca, and a = 18.2113(7), b = 8.8172(3), c = 5.2050(2) Å, V = 835.79(9) Å³. The composition of the orthopyroxene was determined combining EMP, LA-ICP-MS and single-crystal XRD analysis, yielding the unit formula ^M2(Mg_0.59Fe _0.21 ²⁺ Li_0.20) ^M1(Mg_0.74Fe _0.20 ³⁺ Fe _0.06 ²⁺ ) Si₂O₆. Structure refinements done on crystals obtained from synthesis runs with variable Mg-content show that the orthopyroxene is virtually constant in composition and hence in structure, whereas coexisting clinopyroxenes occurring both as individual grains or thin rims around the orthopyroxene crystals have variable amounts of Li, Fe³⁺ and Mg contents. Structure refinement shows that Li is ordered at the M2 site and Fe³⁺ is ordered at the M1 site of the orthopyroxene, whereas Mg (and Fe²⁺) distributes over both octahedral sites. The main geometrical variations observed for Li-rich samples are actually due to the presence of Fe³⁺, which affects significantly the geometry of the M1 site; changes in the geometry of the M2 site due to the lower coordination of Li are likely to affect both the degree and the kinetics of the non-convergent Fe²⁺-Mg ordering process in octahedral sites.  相似文献   

The Utilization and Modeling of Photo-Fenton Process as a Single Unit in Textile Wastewater Treatment     

Bülent Sarı  Selman Türkeş  Hakan Güney  Olcayto Keskinkan 《洁净——土壤、空气、水》2023,51(1):2100328

Studies on the direct application of the photo-Fenton process (PFOP) to disinfect and decontaminate textile wastewater are rare. The output of the artificial neural network (ANN) models applied to the wastewater of a textile factory producing woven fabrics, which is used to assess the efficiency of the PFOP process, are investigated and compared with each other in this study. The highest PFOP efficiency is obtained at a pH of 3. Chemical oxygen demand (COD), suspended solids (SS) and color removal rates are 94%, 90%, and 96%, respectively. The data are modeled with ANNs and nonlinear external input autoregressive ANNs (NARX-ANN) using the MATLAB R2020a software program. Both Levenberg–Marquardt (trainlm) and scaled conjugate gradient (trainscg) algorithms are employed in the ANN and NARX-ANN models, whereas hyperbolic tangent sigmoid (Tansig) and logistic sigmoid (Logsig) functions are superimposed on the hidden layer in the ANN model, and Tansig functions are superimposed on the NARX-ANN model. It is determined that the developed ANN models are more effective in estimating the PFOP efficiency. The mean squared error is 0.000 953, and the coefficient of determination (R²) is 0.96 661.  相似文献   

Distributions-oriented wind forecast verification by a hidden Markov model for multivariate circular–linear data     

Gianluca?MastrantonioEmail authorView author&#;s OrcID profile  Alessio?Pollice  Francesca?Fedele 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(1):169-181

Winds from the North–West quadrant and lack of precipitation are known to lead to an increase of PM10 concentrations over a residential neighborhood in the city of Taranto (Italy). In 2012 the local government prescribed a reduction of industrial emissions by 10% every time such meteorological conditions are forecasted 72 h in advance. Wind forecasting is addressed using the Weather Research and Forecasting (WRF) atmospheric simulation system by the Regional Environmental Protection Agency. In the context of distributions-oriented forecast verification, we propose a comprehensive model-based inferential approach to investigate the ability of the WRF system to forecast the local wind speed and direction allowing different performances for unknown weather regimes. Ground-observed and WRF-forecasted wind speed and direction at a relevant location are jointly modeled as a 4-dimensional time series with an unknown finite number of states characterized by homogeneous distributional behavior. The proposed model relies on a mixture of joint projected and skew normal distributions with time-dependent states, where the temporal evolution of the state membership follows a first order Markov process. Parameter estimates, including the number of states, are obtained by a Bayesian MCMC-based method. Results provide useful insights on the performance of WRF forecasts in relation to different combinations of wind speed and direction.  相似文献   

Sharp spatially constrained inversion with applications to transient electromagnetic data   总被引：1，自引：0，他引：1       下载免费PDF全文

Gianluca Fiandaca  Anders Vest Christiansen  Casper Kirkegaard  Esben Auken 《Geophysical Prospecting》2015,63(1):243-255

Time‐domain electromagnetic data are conveniently inverted by using smoothly varying 1D models with fixed vertical discretization. The vertical smoothness of the obtained models stems from the application of Occam‐type regularization constraints, which are meant to address the ill‐posedness of the problem. An important side effect of such regularization, however, is that horizontal layer boundaries can no longer be accurately reproduced as the model is required to be smooth. This issue can be overcome by inverting for fewer layers with variable thicknesses; nevertheless, to decide on a particular and constant number of layers for the parameterization of a large survey inversion can be equally problematic. Here, we present a focusing regularization technique to obtain the best of both methodologies. The new focusing approach allows for accurate reconstruction of resistivity distributions using a fixed vertical discretization while preserving the capability to reproduce horizontal boundaries. The formulation is flexible and can be coupled with traditional lateral/spatial smoothness constraints in order to resolve interfaces in stratified soils with no additional hypothesis about the number of layers. The method relies on minimizing the number of layers of non‐vanishing resistivity gradient, instead of minimizing the norm of the model variation itself. This approach ensures that the results are consistent with the measured data while favouring, at the same time, the retrieval of horizontal abrupt changes. In addition, the focusing regularization can also be applied in the horizontal direction in order to promote the reconstruction of lateral boundaries such as faults. We present the theoretical framework of our regularization methodology and illustrate its capabilities by means of both synthetic and field data sets. We further demonstrate how the concept has been integrated in our existing spatially constrained inversion formalism and show its application to large‐scale time‐domain electromagnetic data inversions.  相似文献   

The Seismotectonics of the Po Plain (Northern Italy): Tectonic Diversity in a Blind Faulting Domain     

Paola?VannoliEmail author  Pierfrancesco?Burrato  Gianluca?Valensise 《Pure and Applied Geophysics》2015,172(5):1105-1142

We present a systematic and updated overview of a seismotectonic model for the Po Plain (northern Italy). This flat and apparently quiet tectonic domain is, in fact, rather active as it comprises the shortened foreland and foredeep of both the Southern Alps and the Northern Apennines. Assessing its seismic hazard is crucial due to the concentration of population, industrial activities, and critical infrastructures, but it is also complicated because (a) the region is geologically very diverse, and (b) nearly all potential seismogenic faults are buried beneath a thick blanket of Pliocene–Pleistocene sediments, and thus can be investigated only indirectly. Identifying and parameterizing the potential seismogenic faults of the Po Plain requires proper consideration of their depth, geometry, kinematics, earthquake potential and location with respect to the two confronting orogens. To this end, we subdivided them into four main, homogeneous groups. Over the past 15 years we developed new strategies for coping with this diversity, resorting to different data and modeling approaches as required by each individual fault group. The most significant faults occur beneath the thrust fronts of the Ferrara-Romagna and Emilia arcs, which correspond to the most advanced and buried portions of the Northern Apennines and were the locus of the destructive May 2012 earthquake sequence. The largest known Po Plain earthquake, however, occurred on an elusive reactivated fault cutting the Alpine foreland south of Verona. Significant earthquakes are expected to be generated also by a set of transverse structures segmenting the thrust system, and by the deeper ramps of the Apennines thrusts. The new dataset is intended to be included in the next version of the Database of Individual Seismogenic Sources (DISS; http://diss.rm.ingv.it/diss/, version 3.2.0, developed and maintained by INGV) to improve completeness of potential sources for seismic hazard assessment.  相似文献   

Speciation and Determination of Inorganic Mercury and Methylmercury by Headspace Single Drop Microextraction and Electrothermal Atomic Absorption Spectrometry in Water and Fish     

Deniz Yurtsever Sarıca  Ali Rehber Türker 《洁净——土壤、空气、水》2012,40(5):523-530

In this study, headspace single drop microextraction (HS‐SDME) method in combination with electrothermal atomic absorption spectrometry (ETAAS) method was developed and validated for the speciation and determination of inorganic mercury (iHg) and methylmercury (MeHg). MeHg and iHg species were reduced to volatile methylmercury hydride (CH₃HgH) and elemental mercury, respectively, in the presence of NaBH₄ and trapped onto a drop of acceptor phase in the tip of a microsyringe. Thiourea and ammonium pyrrolydinedithiocarbamate (APDC) were tested as the acceptor phase. The experimental parameters of the method such as microextraction time, temperature, NaBH₄ concentration, acceptor phase concentration, and pH of the medium were investigated to obtain distinctive conditions for mercury species. Possible interference effects have also been investigated. In order to validation of the method, analytical figures of merits such as accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), and linear working range have been evaluated. Accuracy of the method has been verified by analyzing certified reference materials (BCR 453 Tuna fish) and spiked samples. The proposed method was applied for the speciation and determination of mercury species in water and fish samples. Mercury species (MeHg and iHg) have been determined in the real samples with a relative error less than 10%.  相似文献   

A note on maar eruption energetics: current models and their application   总被引：1，自引：1，他引：0  

Jacopo Taddeucci  Gianluca Sottili  Danilo M. Palladino  Guido Ventura  Piergiorgio Scarlato 《Bulletin of Volcanology》2010,72(1):75-83

Hydromagmatic eruptions convert thermal into mechanical energy via the expansion of ground- and/or surface-water. Several models address the energetics of these eruptions based on different physical-volcanological approaches. Here we test different models with two case studies in the Colli Albani Volcanic District (central Italy): the monogenetic Prata Porci and the polygenetic Albano maars. Test results are mutually consistent, and show cumulative mechanical energy releases on the order of 10¹⁵–10¹⁷ J for single maars. The fraction of thermal energy turned into mechanical ranges from 0.45 (as calculated from the theoretical maximum mechanical energy), through 0.1 (calculated from country rock fragmentation, crater formation and ballistic ejection), to 0.03 (derived from magma fragmentation by thermohydraulic explosions). It appears that the energy released during the most intense hydromagmatic events may account for a dominant fraction of the total mechanical energy released during the whole maar eruptive histories. Finally, we consider the role of magmatic explosive activity intervening during maar eruptions in causing departures from predictions of the models evaluated.  相似文献   

Numerical simulation of the tsunami generated by a past catastrophic landslide on the volcanic island of Ischia, Italy     

Stefano Tinti  Francesco Latino Chiocci  Filippo Zaniboni  Gianluca Pagnoni  Giovanni de Alteriis 《Marine Geophysical Researches》2011,32(1-2):287-297

The island of Ischia, Gulf of Naples, Italy, like many other volcanic islands is affected by mass failures, that are mainly related to secondary volcanic processes such as slope steepening and seismic shaking. The block resurgence of its main relief, Mount Epomeo, has been recognised to contribute cyclically to mass instability and cause landslides, that occasionally may reach the sea and start tsunamis. In this work we explore the consequences of the Ischia Debris Avalanche (IDA), a flank collapse that occurred in historical times, and involved the whole Mount Epomeo edifice including its submarine portion, and that may have caused gigantic sea waves affecting all the coasts of Ischia and of the Gulf of Naples. The IDA and the generated tsunami have been taken as the worst-case scenario for the occurrence of a new tsunami in the area. They have been simulated through numerical codes developed and maintained by the University of Bologna. The simulation shows that the IDA-induced tsunami attacks severely all the coasts of the Gulf of Naples with the highest waves obtained for the island of Ischia, the island of Capri and the peninsula of Sorrento. The propagation pattern of the IDA tsunami can be used to get hints on the impact that such an event may have had on early populations habiting Gulf of Naples, but also to get clues on the area that could be most severely hit by a tsunami generated by a smaller-scale landslide that may occur in the same source zone.  相似文献   

Tectonic implications of transtensional supradetachment basin development in an extension‐parallel transfer zone: the Kocaçay Basin,western Anatolia,Turkey     

Hasan Sözbilir  Bilal Sarι  Bora Uzel  Ökmen Sümer  Serkan Akkiraz 《Basin Research》2011,23(4):423-448

The Kocaçay Basin (KÇB) is a key area in western Anatolia – a well‐known extended terrane where regional segmentation has received limited attention – for investigating strike‐slip faults kinematically linked to detachment faults. In this paper, we present results of an integrated sedimentologic, stratigraphic, and structural study of Miocene alluvial fan/fan‐delta/lacustrine deposits that accumulated in the KÇB, a NE‐trending basin with connections to the Menderes Metamorphic Core Complex (MCC). We mapped and evaluated most of the key faults in the KÇB, many for the first time, and recognised different deformation events in the study area near the E margin of the MCC. We also present field evidence for kinematic connections between low‐angle normal and strike‐slip faults which were developed in an intermittently active basement‐involved transfer zone in western Anatolia. We find that the KÇB contains a detailed record of Miocene transtensional sedimentation and volcanism that accompanied exhumation of the MCC. Structural data reveal that the basin was initially formed by transtension (D1 phase) and subsequently uplifted and deformed, probably as a result of early Pliocene wrench‐ to extension‐dominated deformation (D2 phase) overprinted by Plio‐Quaternary extensional tectonics (D3 phase). These results are consistent with progressive deformation wherein the axis of maximum extension remained in the horizontal plane but the intermediate and maximum shortening axes switched position in the vertical plane. Combining our results with published studies, we propose a new working hypothesis that the KÇB was a transtensional supradetachment basin during the Miocene. The hypothesis could provide new insights into intermittently active extension‐parallel zone of weakness in western Anatolia.These results also suggest that the termination of low‐angle normal fault systems within an extension parallel transfer zone may have resulted in a transtensional depressions which are different from classical supradetachment basins with respect to the sedimentation and deformational pattern of the basin infills.  相似文献   

The control of cooling rate on titanomagnetite composition: implications for a geospeedometry model applicable to alkaline rocks from Mt. Etna volcano     

Silvio Mollo  Keith Putirka  Gianluca Iezzi  Piergiorgio Scarlato 《Contributions to Mineralogy and Petrology》2013,165(3):457-475

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