OH point defects in olivine from Pakistan     

Jürgen Gose  Esther Schmädicke  Margit Markowitz  Anton Beran 《Mineralogy and Petrology》2010,99(1-2):105-111

The infrared (IR) spectra of gem-quality olivine crystals from Pakistan, formed in serpentinised dunitic rocks, are characterised by strongly pleochroic absorption bands at 3,613, 3,597, 3,580 and 3,566 cm^?1. These bands are assigned to O-H stretching vibrations of OH point defects corresponding to H₂O concentrations of about 35 wt ppm. Unlike other olivine spectra, the dominating bands are strongly polarised parallel to the b-axis. The unusual spectra type, excludes the presence of planar defects. This finding is supported by transmission electron microscopy. The 3,613 cm^?1 band is related to vacant Si sites, the slightly lower energetic bands preferentially to vacant M2 sites. The exclusive presence of these bands is not only a characteristic feature of olivines treated under high P,T conditions equivalent to mantle environment, the presence of these bands in untreated natural olivine also indicates formation conditions equivalent to crustal rocks.  相似文献   

The Hague as the disputed showcase of the Dutch State and Dutch national identity 1814–1917     

Esther M. Agricola 《GeoJournal》2000,51(1-2):47-56

The central question of this article is What does the urban and architectural design of The Hague tell us about the Dutch political and administrative ambitions in representing the state and national identity from 1814–1917? In this period many European capital cities grew fast, governmentas acquired new ambitions and new powers, and nationalism spread. Many governments developed impressive national building activities. In The Netherlands there was hardly any urge to emphasize the state power by transforming the urban landscape even in its governmental center The Hague. One reason is that the dominant liberal politics refrained from social and economic interventions. A second reason is that the various population groups had difficulty to agree on one national building style. Accompanied by a strong ideological discussion, the Dutch polity finally succeeded in producing a governmental architecture (from ca. 1880–1815) in the so-called Dutch Renaissance style. Although the different population groups (orthodox Protestants, Liberals, Catholics) could, each for their own reasons, accept this national style, its characteristics (picturesque, simple and small) lent itself poorly to public governmental commissions on a grand scale.  相似文献   

Chemical composition of landfill leachate in a karst area with a Mediterranean climate (Marbella, southern Spain)   总被引：2，自引：0，他引：2  

I. Vadillo  F. Carrasco  B. Andreo  A. García de Torres  C. Bosch 《Environmental Geology》1999,37(4):326-332

 Between March 1994 and April 1997, the physical and chemical parameters and chemical composition of the urban solid waste leachate of the Marbella landfill (southern Spain) were determined. The data obtained show an ammonium and sodium chloride and bicarbonate type, a pH>7 and high mineralization, effectively described by the following parameters: Na⁺, K⁺, NH₄ ⁺, Cl^– and alkalinity. The chemical composition depends on the rainfall: in dry years, the mineralization and component concentrations have values as much as double those found in normal rainfall years. After storm events, a major and rapid dilution (within several hours) is seen in the leachate. Received: 28 January 1998 · Accepted: 2 June 1998  相似文献   

A GIS method to identify flat surfaces and restore relict fluvial long-profiles from terrace remnants gives new clues on how large basins respond to endorheic–exorheic transitions (Duero basin,Iberian Peninsula)     

Laura Rodríguez-Rodríguez  Loreto Antón  Raimon Pallàs  Daniel García-Castellanos  Ivone Jiménez-Munt  Candela Pastor-Martín 《地球表面变化过程与地形》2020,45(4):1013-1027

Fluvial terraces are used as geomorphic indicators for deciphering long-term landscape evolution. Knowing the distribution of fluvial terraces is essential for establishing former river profiles and their tectonic significance, for studying climate-modulated processes of terrace development, or for defining fluvial network adjustments in response to sudden base-level changes like those produced by fluvial captures. Multiple methods for automatic map production have been proposed based on the comparison of morphometric indices with those of the modern river course. Here we propose an alternative method to identify flat surfaces and scarps separating them from digital elevation models without setting comparisons with a modern river course and thus fully applicable to study flat landforms whatever their origin. Its application to the low-relief landscape of the Cenozoic Duero basin has allowed the improvement of previous geomorphological maps and the analysis of fluvial network adjustments in response to a sudden base-level fall after the opening of the Neogene endorheic basin towards the Atlantic Ocean. Reconstructed terrace long-profiles suggest an initial episode of fast vertical incision followed by a period of repeated planation–aggradation–incision with the formation of 14 to 13 unpaired terrace levels. Changes observed in the pattern of terrace profiles are discussed with regard to changes in regional tectonics and base-level variations. © 2019 John Wiley & Sons, Ltd.  相似文献   

New Insights on Mt. Etna’s Crust and Relationship with the Regional Tectonic Framework from Joint Active and Passive P-Wave Seismic Tomography     

A. Díaz-Moreno  G. Barberi  O. Cocina  I. Koulakov  L. Scarfì  L. Zuccarello  J. Prudencio  A. García-Yeguas  I. Álvarez  L. García  J. M. Ibáñez 《Surveys in Geophysics》2018,39(1):57-97

In the Central Mediterranean region, the production of chemically diverse volcanic products (e.g., those from Mt. Etna and the Aeolian Islands archipelago) testifies to the complexity of the tectonic and geodynamic setting. Despite the large number of studies that have focused on this area, the relationships among volcanism, tectonics, magma ascent, and geodynamic processes remain poorly understood. We present a tomographic inversion of P-wave velocity using active and passive sources. Seismic signals were recorded using both temporary on-land and ocean bottom seismometers and data from a permanent local seismic network consisting of 267 seismic stations. Active seismic signals were generated using air gun shots mounted on the Spanish Oceanographic Vessel ‘Sarmiento de Gamboa’. Passive seismic sources were obtained from 452 local earthquakes recorded over a 4-month period. In total, 184,797 active P-phase and 11,802 passive P-phase first arrivals were inverted to provide three different velocity models. Our results include the first crustal seismic active tomography for the northern Sicily area, including the Peloritan–southern Calabria region and both the Mt. Etna and Aeolian volcanic environments. The tomographic images provide a detailed and complete regional seismotectonic framework and highlight a spatially heterogeneous tectonic regime, which is consistent with and extends the findings of previous models. One of our most significant results was a tomographic map extending to 14 km depth showing a discontinuity striking roughly NW–SE, extending from the Gulf of Patti to the Ionian Sea, south-east of Capo Taormina, corresponding to the Aeolian–Tindari–Letojanni fault system, a regional deformation belt. Moreover, for the first time, we observed a high-velocity anomaly located in the south-eastern sector of the Mt. Etna region, offshore of the Timpe area, which is compatible with the plumbing system of an ancient shield volcano located offshore of Mt. Etna.  相似文献   

Earthquake-induced damage detection and localization in masonry structures using smart bricks and Kriging strain reconstruction: A numerical study     

Enrique García-Macías  Filippo Ubertini 《地震工程与结构动力学》2019,48(5):548-569

The intrinsic vulnerability of masonry structures to seismic events makes structural health monitoring of the utmost importance for the conservation of the built heritage. The development of piezoresistive bricks, also termed smart bricks, is an innovative technology recently proposed by the authors for the monitoring of such structures. Smart bricks exhibit measurable variations in their electrical properties when subjected to external loads or, alternatively, strain self-sensing capabilities. Therefore, the deployment of a network of smart bricks into a masonry structure confers self-diagnostic properties to the host structure. In this light, this paper presents a theoretical investigation on the application of smart bricks to full-scale masonry structures for seismic assessment. This includes the study of the convenience of providing electrical isolation conditions to the sensors, as well as the effectiveness of smart bricks when installed into either new constructions or in pre-existing structures. Secondly, numerical results are presented on the seismic analysis of a three-dimensional masonry building equipped with a network of smart bricks. Finally, in order to map the strain field throughout the structure exploiting the outputs of a limited number of sensors, an interpolation-based strain reconstruction approach is proposed.  相似文献   

The dimensional character of permeability: Dimensionless groups that govern Darcy's flow in anisotropic porous media     

Iván Alhama  Encarnación Martínez-Moreno  Gonzalo García-Ros 《国际地质力学数值与分析法杂志》2023,47(1):129-141

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