Ostracods as tsunami tracers in Holocene sequences     

Francisco Ruiz  Manuel Abad  Joaquín Rodríguez Vidal  Manuel Pozo 《Quaternary Research》2010,73(1):130-239

This review analyses the ostracod record in Holocene tsunami deposits, using an overview of the 2004 Indian Ocean tsunami impact on its recent populations and the associated tsunamigenic deposits, together with results from numerous investigations of other Holocene sequences. Different features such as the variability of the local assemblages, population density, species diversity, age population structure (e.g., percentages of adults and juvenile stages) or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high-energy events in marshes, lakes, lagoons or shallow marine areas.  相似文献   

Measuring ΩM and ΩΛ with long‐duration gamma‐ray bursts     

A. Balastegui  R. Canal  P. Ruiz‐Lapuente 《Astronomische Nachrichten》2010,331(8):837-842

Gamma‐ray bursts (GRBs) are one of the most luminous events in the Universe. In addition, the Universe itself is almost transparent to γ ‐rays, making GRBs detectable up to very high redshifts. As a result, GRBs are very suitable to probe the cosmological parameters. This work shows the potential of long‐duration GRBs for measuring the cosmological parameters Ω_M and Ω_Λ by comparing the observed log N ‐log P distribution with the theoretical one. Provided that the GRBs rate and luminosity function are well determined, the best values and 1σ confidence intervals obtained are Ω_M = 0.22^+0.05_–0.03 and Ω_Λ = 1.06^+0.05_–0.10. Finally, a set of simulations show the ability of the method to measure Ω_M and Ω_Λ (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

The role of small‐scale fold and fault development in seismogenic zones: example of the western Huércal‐Overa Basin (eastern Betic Cordillera,Spain)     

Antonio Pedrera  Jesús Galindo‐Zaldívar  Antonio Ruiz‐Bustos  José Rodríguez‐Fernández  Ana Ruiz‐Constán 《第四纪科学杂志》2009,24(6):581-592

The NW–SE shortening between the African and the Eurasian plates is accommodated in the eastern Betic Cordillera along a broad area that includes large N‐vergent folds and kilometric NE–SW sinistral faults with related seismicity. We have selected the best exposed small‐scale tectonic structures located in the western Huércal‐Overa Basin (Betic Cordillera) to discuss the seismotectonic implications of such structures usually developed in seismogenic zones. Subvertical ESE–WNW pure dextral faults and E–W to ENE–ESW dextral‐reverse faults and folds deform the Quaternary sediments. The La Molata structure is the most impressive example, including dextral ESE–WNW Neogene faults, active southward‐dipping reverse faults and associated ENE–WSW folds. A molar M1 assigned to Mimomys savini allows for precise dating of the folded sediments (0.95–0.83 Ma). Strain rates calculated across this structure give ～0.006 mm a^?1 horizontal shortening from the Middle Pleistocene up until now. The widespread active deformations on small‐scale structures contribute to elastic energy dissipation around the large seismogenic zones of the eastern Betics, decreasing the seismic hazard of major fault zones. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Influence of the spatial distribution of energy-dissipating bracing elements on the seismic response of multistorey frames     

Sonia E. Ruiz  Olga E. Urrego  Francisco L. Silva 《地震工程与结构动力学》1995,24(11):1511-1525

Several reinforced concrete frames with different dissipator distributions, and a conventional moment-resisting frame, are compared in order to select the best dissipator distribution from the point of view of seismic response and structural design. The structures with dissipators are designed according to a criterion proposed in the present paper. Each frame is excited with a set of eleven simulated accelerograms. The choice of the best dissipation distribution is based mainly on the differences between the mean of the maximum overturning moments developed at the base of the frames and between the weights of steel reinforcement and concrete resulting from the structural design of each frame. A comparison of initial construction costs of a building with dissipators and a conventional building shows that the former is 3·5 per cent more expensive.  相似文献   

Acoustic emission during swelling and contraction tests     

V.G. Ruiz de Argandofia  L. Calleja  L.M. Surez del Rio 《Engineering Geology》1995,39(3-4):147-150

An expansive clayey rock belonging to the Asturias Carboniferous of NW Spain has been petrophysically characterized before, during and after swelling tests. The evolution of the microfissuring and the induced deterioration have been studied by acoustic emission during tests and by ultrasonic techniques before and after swelling/contraction cycles. A good correlation has been found between the AE curves and swelling strain. Damage due to the generation and growth of microfissures is most important during the first moments of each swelling/contraction cycle. Microfissures mainly develop in the direction of the foliation planes, as can be shown by linear crack density and measurements of the propagation velocity of longitudinal waves.  相似文献   

Le complexe filonien de Fuerteventura (Iles Canaries)     

J. Lopez Ruiz 《Bulletin of Volcanology》1969,33(4):1166-1185

Two sectors in the island have been distinguished which depend on the intensity of the penetration of the dyke swarm: the central-western sector, where the proportion of dykes in relation to the host rocks is — in some cases — more than 90% and all the rest of the island, where the dykes are in less proportion. In the central-western sector the predominant direction varies from N-10^o-E to N-20^o-E, whilst in the rest of the island a clear constant direction does not exist, although there are some directional trends more or less well defined. Most dykes are of basaltic composition, but there are also salic dykes (trachytic and phonolitic) and camptonites. The dykes from the western sector have suffered intense transformation processes (albitization and amphibolization), so that it is frequent to find dykes that do not preserve practically any one of their primary minerals. As the albitization process also affects the host rocks and has a regional development; we can speak of a regional metamorphism equivalent in its intensity to the Green Schist. Three main generations of dykes have been established: 1st) those of an approximately N-S direction, forming the older generation, constituted by multiple injections, 2nd) those genetically related to the Basaltic Series I, 3rd) those of salic composition, closely related with the syenitic-trachytic intrusions.  相似文献   

Loss on ignition: a qualitative or quantitative method for organic matter and carbonate mineral content in sediments?   总被引：5，自引：7，他引：5  

Juan I. Santisteban  Rosa Mediavilla  Enrique López-Pamo  Cristino J. Dabrio  M. Blanca Ruiz Zapata  M. José Gil García  Silvino Castaño  Pedro E. Martínez-Alfaro 《Journal of Paleolimnology》2004,32(3):287-299

Since the publication of the paper of , loss on ignition (LOI) has been widely used as a method to estimate the amount of organic matter and carbonate mineral content (and indirectly of organic and inorganic carbon) in sediments. The relationships between LOI at 550 °C (LOI₅₅₀) and organic carbon (OC) content and between LOI at 950 °C (LOI₉₅₀) and inorganic carbon (IC) content are currently accepted as a standard. However, the comparison of 150 analyses of samples of diverse lithologies, collected from a single core, reveals that these relationships are affected by sediment composition (presence of clays, salts, and the variable content of organic carbon). This results in an incremental error on the estimation of carbon content from LOI values that invalidates the use of LOI values as a quantitative method for estimating carbon content. Conversely, the general trends of LOI₅₅₀ and LOI₉₅₀ show a good correlation with carbon content (both organic and inorganic) allowing use of LOI as a qualitative test for carbon content. Similarly, in our case, LOI at 105 °C (LOI₁₀₅) is a good qualitative proxy for the trends in gypsum content.  相似文献   

Cu isotopic fractionation in the supergene environment with and without bacteria   总被引：5，自引：0，他引：5  

Ryan Mathur  Joaquin Ruiz  Laura Liermann  Susan Brantley 《Geochimica et cosmochimica acta》2005,69(22):5233-5246

The isotopic composition of dissolved Cu and solid Cu-rich minerals [δ⁶⁵Cu (‰) = (⁶⁵Cu/⁶³Cu_sample/⁶⁵Cu/⁶³Cu_std) - 1)*1000] were monitored in batch oxidative dissolution experiments with and without Thiobacillus ferrooxidans. Aqueous copper in leach fluids released during abiotic oxidation of both chalcocite and chalcopyrite was isotopically heavier (δ⁶⁵Cu = 5.34‰ and δ⁶⁵Cu = 1.90‰, respectively, [±0.16 at 2σ]) than the initial starting material (δ⁶⁵Cu = 2.60 ± 0.16‰ and δ⁶⁵Cu = 0.58 ± 0.16‰, respectively). Isotopic mass balance between the starting material, aqueous copper, and secondary minerals precipitated in these experiments explains the heavier isotopic values of aqueous copper. In contrast, aqueous copper from leached chalcocite and chalcopyrite inoculated with Thiobacillus ferrooxidans was isotopically similar to the starting material. The lack of fractionation of the aqueous copper in the biotic experiments can best be explained by assuming a sink for isotopically heavy copper present in the bacteria cells with δ⁶⁵Cu = 5.59 ± 0.16‰. Consistent with this inference, amorphous Cu-Fe oxide minerals are observed surrounding cell membranes of Thiobacillus grown in the presence of dissolved Cu and Fe.Extrapolating these experiments to natural supergene environments implies that release of isotopically heavy aqueous Cu from oxidative leach caps, especially under abiotic conditions, should result in precipitates in underlying enrichment blankets that are isotopically heavy. Where iron-oxidizing cells are involved, isotopically heavy oxidized Cu entrained in cellular material may become associated with leach caps, causing the released aqueous Cu to be less isotopically enriched in the heavy isotope than predicted for the abiotic system. Rayleigh fractionation trends with fractionation factors calculated from our experiments for both biotic and abiotic conditions are consistent with large numbers of individual abiotic or biotic leaching events, explaining the supergene chalcocites in the Morenci and Silver Bell porphyry copper deposits.  相似文献   

Visualization of Volcanic Rock Geochemical Data and Classification with Artificial Neural Networks   总被引：1，自引：0，他引：1  

Juan Pablo Lacassie  Javier Ruiz del Solar  Barry Roser  Francisco Hervé 《Mathematical Geology》2006,38(6):697-710

An unsupervised neural network technique, Growing Cell Structures (GCS) was used to visualize geochemical differences between four different island arc volcanic rock types: basalts, andesites, dacites and rhyolites. The output of the method shows the cluster structure of the dataset clearly, and the relevant geochemical patterns and relationships between its variables. The data can be separated into four clusters, each associated with a specific volcanic rock type (basalt, andesite, dacite and rhyolite), according to a unique combination of major element concentrations. Following clustering, performance of the trained GCS network as a classifier of volcanic rock type was tested using two test datasets with major element concentration data for 312 and 496 island arc volcanic rock samples of known volcanic type. Preliminary classification results are promising. In the first test dataset 94% of basalts, 76% of andesites, 83% of dacites and 100% of the rhyolites were classified correctly. Successful classification rates in the second dataset were 100%, 80%, 77%, and 98% respectively. The success of the analysis suggests that neural networks analysis constitutes a useful analytical tool for identification of natural clusters and examination of the relationships between numeric variables in large datasets, and that can be used for automatic classification of new data.  相似文献   

Seismic activity at the western Pyrenean edge   总被引：1，自引：1，他引：1  

M. Ruiz  J. Gallart  J. Díaz  C. Olivera  D. Pedreira  C. Lpez  J.M. Gonzlez-Cortina  J.A. Pulgar 《Tectonophysics》2006,412(3-4):217-235

The present-day seismicity at the westernmost part of the Pyrenean domain reported from permanent networks is of low to moderate magnitude. However, it is poorly constrained due to the scarce station coverage of the area. We present new seismic data collected from a temporary network deployed there for 17 months that provides an enhanced image of the seismic activity and its tectonic implications. Our results delineate the westward continuity of the E–W Pyrenean band of seismicity, through the Variscan Basque Massifs along the Leiza Fault, ending up at the Hendaya Fault. This seismicity belt is distributed on a crustal scale, dipping northward to almost 30 km depth. Other relevant seismic events located in the area can be related to the central segment of the Pamplona fault, and to different E–W thrust structures.  相似文献