Mesozoic to Tertiary tectonic history of the Mirdita ophiolites, northern Albania   总被引：3，自引：0，他引：3  

Valerio  Bortolotti  Michele  Marroni  Luca  Pandolfi  Gianfranco  Principi 《Island Arc》2005,14(4):471-493

Abstract In this paper, a summary of the tectonic history of the Mirdita ophiolitic nappe, northern Albania, is proposed by geological and structural data. The Mirdita ophiolitic nappe includes a subophiolite mélange, the Rubik complex, overlain by two ophiolite units, referred to as the Western and Eastern units. Its history started in the Early Triassic with a rifting stage followed by a Middle to Late Triassic oceanic opening between the Adria and Eurasia continental margins. Subsequently, in Early Jurassic time, the oceanic basin was affected by convergence with the development of a subduction zone. The existence of this subduction zone is provided by the occurrence of the supra‐subduction‐zone‐related magmatic sequences found in both the Western and Eastern units of the Mirdita ophiolitic nappe. During the Middle Jurassic, continuous convergence resulted in the obduction of the oceanic lithosphere, in two different stages – the intraoceanic and marginal stages. The intraoceanic stage is characterized by the westward thrusting of a young and still hot section of oceanic lithosphere leading to the development of a metamorphic sole. In the Late Jurassic, the marginal stage developed by the emplacement of the ophiolitic nappe onto the continental margin. During this second stage, the emplacement of the ophiolites resulted in the development of the Rubik complex. In the Early Cretaceous, the final emplacement of the ophiolites was followed by the unconformable sedimentation of the Barremian–Senonian platform carbonate. From the Late Cretaceous to the Middle Miocene, the Mirdita ophiolitic nappe was translated westward during the progressive migration of the deformation front toward the Adria Plate. In the Middle to Late Miocene, a thinning of the whole nappe pile was achieved by extensional tectonics, while the compression was still active in the westernmost areas of the Adria Plate. On the whole, the Miocene deformations resulted in the uplift and exposition of the Mirdita ophiolites as observed today.  相似文献   

Polarized XANES and EXAFS spectroscopic investigation into copper(II) complexes on vermiculite   总被引：1，自引：0，他引：1  

Luca J. Furnare  Daniel G. Strawn 《Geochimica et cosmochimica acta》2005,69(22):5219-5231

Interaction of heavy metals with clay minerals can dominate solid-solution reactions in soil, controlling the fate of the metals in the environment. In this study we used powdered and polarized extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge spectroscopy (XANES) to investigate Cu sorbed on Llano vermiculite and compare the results to reported Cu sorption mechanism on Wyoming (WY) smectite and reduced South African (SA) vermiculite. Analysis of the Cu K-edge spectra revealed that Cu sorbed on Llano vermiculite at high ionic strength (I) has the greatest degree of covalent bond character, followed by Cu sorbed on montmorillonite at high I, and Cu sorbed on reduced SA vermiculite at high I. Cu sorbed on clay minerals at low I has the least covalent character. EXAFS data from Cu sorbed Ca- and K-equilibrated Llano vermiculites showed the presence of a second-shell Al, Si, or Mg backscatterer at 3.02 Å. This distance is consistent with Cu sorbing via a corner-sharing monodentate or bidentate bond. Polarized XANES and EXAFS results revealed that the angle between the Cu atom and the mineral sorption sites is 68° with respect to the [001] direction. From the bond angle and the persistence of the second-shell backscatterer when the interlayer is collapsed (K-equilibration), we conclude that Cu adsorption on the Llano vermiculite is not occurring in the interlayer but rather Cu is adsorbing onto the edges of the vermiculite. Results from this research provide evidence that Cu forms inner-sphere and outer-sphere complexes on clay minerals, and does not form the vast multinuclear surface precipitates that have been observed for Co, Zn, and Ni.  相似文献   

意大利埃特纳火山的三维速度结构与地震活动性   总被引：2，自引：2，他引：0  

Luca  G 《CT理论与应用研究》1998,7(1):43-51

本文的研究工作,得到了埃特纳火山下面的一组新的三维速度模型。作者们用１９８０年以来地方性地震在永久和临时地震台网在４个或更多台记录到的１２４９次地震的Ｐ和Ｓ波,被选来作走时反演。选择了几种判别标志与参数化办法以显示其类似的基本特征。表明在火山的东南象限在浅层,有Ｐ波的高速分怖,它同布格重力高异常有密切关系。在该区存在低的Ｖｐ／Ｖｓ比值;沿着中央火山管道,分布有高速Ｐ波和高的Ｖｐ／Ｖｓ比值;建议该处存在有稠密的侵入的岩浆体,延伸到２０千米左右的深度,该区附近有低速的Ｐ波速度。对震源的重新定位也显示出向外倾斜的易碎区,与中央火山管道延伸出一段Ｐ波高速异常区,位于中央火山口的附近。沿着中央火山口附近,有Ｐ波的低速区,它同次生的火山锥的分布有关,与部份熔融的深部岩浆库有联系。  相似文献   

Effect of hydrologic management on marsh surface sediment deposition in coastal Louisiana     

Denise J. Reed  Nina De Luca  A. Lee Foote 《Estuaries and Coasts》1997,20(2):301-311

High rates of coastal land loss in Louisiana have prompted efforts to maintain or restore coastal wetland habitats, and structural management of marsh hydrology is one of a number of approaches that has been adopted. The aim of this study was to determine the effect of hydrologic management measures on marsh-surface sediment deposition in the Mississippi deltaic plain. Four impoundments, ranging in size from 50 ha to 177 ha and similarly sized control sites were included in the study. At each site, marsh-surface sediment traps were collected approximately biweekly for 3.5 yr to measure changes in sediment deposition. There was no significant difference in sediment deposition between any of the impoundment and control sites during the premanagement period. The results show no significant difference in marsh-surface sediment deposition between management year 1992–1993 and management year 1994–1995, but management year 1993–1994 had significantly lower sediment deposition than either the first or the last year of the study. Management year 1992–1993 showed the highest sediment deposition when it was assessed across all basins, areas, and sites, and this high rate of deposition is accounted for by the impact of Hurricane Andrew. For all management years there were significant differences between impoundment and control sites, with control sites showing higher rates of marsh surface sediment deposition than impoundments. No clear pattern was identified concerning the influence of various types of hydrologic management on rates of sediment deposition. This reduction in sediment deposition indicated that the areas under management in this study are receiving insufficient inorganic sediment deposition to keep pace with sea-level rise.  相似文献   

Preliminary investigations on the occurrence of diagenetic dolomite in surface sediments of Lagoa Vermelha,Brazil     

I. Moreira  R. Patchineelam Dr.  A. de Luca Rebello 《GeoJournal》1987,14(3):357-360

Studies on the precipitation of carbonates in a hypersaline lagoon revealed the presence of diagenetic dolomite at very shallow sediment depths. The relation of magnesium to calcium concentration both in interstitial and surface waters are within the range predicted in the literature for this occurence. Lower values encountered in some samples were linked to interactions with fresh groundwater.  相似文献   

Late Cretaceous plants from the Bonarelli Level of the Venetian Alps, northeastern Italy     

Bernard Gomez  Frdric Thvenard  Marco Fantin  Luca Giusberti 《Cretaceous Research》2002,23(6):671

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A systematic analysis of the <Emphasis Type="Italic">XMM-Newton</Emphasis> background: II. Properties of the in-Field-Of-View excess component     

David Salvetti  Martino Marelli  Fabio Gastaldello  Simona Ghizzardi  Silvano Molendi  Andrea De Luca  Alberto Moretti  Mariachiara Rossetti  Andrea Tiengo 《Experimental Astronomy》2017,44(3):309-320

We present an accurate characterization of the particle background behaviour on XMM-Newton based on the entire EPIC archive. This corresponds to the largest EPIC data set ever examined. Our results have been obtained thanks to the collaboration between the FP7 European program EXTraS and the ESA R&D ATHENA activity AREMBES. We used as a diagnostic an improved version of the diagnostic which compares the data collected in unexposed region of the detector with the region of the field of view in the EPIC-MOS. We will show that the in Field-of-View excess background is made up of two different components, one associated to flares produced by soft protons and the other one to a low-intensity background. Its origin needs to be further investigated.  相似文献   

A systematic analysis of the XMM-Newton background: I. Dataset and extraction procedures     

Martino Marelli  David Salvetti  Fabio Gastaldello  Simona Ghizzardi  Silvano Molendi  Andrea De Luca  Alberto Moretti  Mariachiara Rossetti  Andrea Tiengo 《Experimental Astronomy》2017,44(3):297-308

XMM-Newton is the direct precursor of the future ESA ATHENA mission. A study of its particle-induced background provides therefore significant insight for the ATHENA mission design. We make use of ～12 years of data, products from the third XMM-Newton catalog as well as FP7 EXTraS project to avoid celestial sources contamination and to disentangle the different components of the XMM-Newton particle-induced background. Within the ESA R&D AREMBES collaboration, we built new analysis pipelines to study the different components of this background: this covers time behavior as well as spectral and spatial characteristics.  相似文献   

Sustainable Yield of a Hydrothermal Area: From Theoretical Concepts to the Practical Approach     

Vincenzo Piscopo  Stefano Di Luca  Michele Dimasi  Francesca Lotti 《Ground water》2019,57(2):337-348

Sustainable use of groundwater in the hydrothermal area of Viterbo (Central Italy) was analyzed. In this area, multipurposes utilization of groundwater coexists: several thermal springs and wells supply spas and public pools, cold and fresh water is used for irrigation and drinking-water. Starting from theoretical concepts, a management plan has been developed to ensure groundwater sustainability in response to the increased demand of withdrawal from thermal wells, by integrating previous hydrogeological studies, new investigations and a new finite-difference model. The most stringent constraints considered are: to maintain the quality of thermal and fresh waters, to limit the effects on the hydraulic equilibrium existing between overlapping aquifers, to ensure a significant flow to the natural thermal springs and the quality and flow rate of the spring used for drinking purposes. The practical approach included identification of the maximum pumping rate from the wells of the spas, analysis of the response time of the system under development and drafting of a safeguard and monitoring plan. The case examined takes into account the complexity of the task in defining practical measures for groundwater management on the basis of theoretical concepts of its sustainable use. A participative approach among the different water decision-makers and adaptive management in the use of groundwater resources with different quality represent the key points to overcome conflicts between different users, with the awareness of the ineludible uncertainties of the hydrogeological model.  相似文献   

The 7 and 11 May 1984 earthquakes in Abruzzo-Latium (Central Italy): reappraisal of the existing macroseismic datasets according to the EMS98     

Laura Graziani  Andrea Tertulliani  Alessandra Maramai  Antonio Rossi  Luca Arcoraci 《Journal of Seismology》2017,21(5):1219-1227

The aim of this paper is to provide a complete and reliable macroseismic knowledge of the events that stroke a large area in Central Italy on 7 and 11 May 1984. Previous studies, together with original accounts integrated with new and unpublished information, have been gathered and examined in order to re-evaluate macroseismic intensities in terms of the European Macroseismic Scale (EMS98). New intensity maps have been compiled; the total number of localities with available information for both the shocks increases from 1254 of the previous study to 1576. On the basis of the new dataset, the macroseismic magnitude of the first shock is M_W 5.6 which is lower than the previous macroseismic computation (M_W 5.7). Moreover, the topic of assessing macroseismic intensity in the presence of multiple shocks has been also investigated, proposing an unconventional approach to presenting the macroseismic data: an overall picture of the cumulative effects produced by all the seismic sequence is given to support a partial but faithful reconstruction of the second shock. This approach is inspired by the common experience in interpreting historical seismic sequences and gives a picture of the impact of the 1984 events on the territory.  相似文献