Compound ultrarefractory CAI‐bearing inclusions from CV3 carbonaceous chondrites     

Marina A. IVANOVA  Alexander N. KROT  Kazuhide NAGASHIMA  Glenn J. MacPHERSON 《Meteoritics & planetary science》2012,47(12):2107-2127

Two compound calcium‐aluminum‐rich inclusions (CAIs), 3N from the oxidized CV chondrite Northwest Africa (NWA) 3118 and 33E from the reduced CV chondrite Efremovka, contain ultrarefractory (UR) inclusions. 3N is a forsterite‐bearing type B (FoB) CAI that encloses UR inclusion 3N‐24 composed of Zr,Sc,Y‐rich oxides, Y‐rich perovskite, and Zr,Sc‐rich Al,Ti‐diopside. 33E contains a fluffy type A (FTA) CAI and UR CAI 33E‐1, surrounded by Wark‐Lovering rim layers of spinel, Al‐diopside, and forsterite, and a common forsterite‐rich accretionary rim. 33E‐1 is composed of Zr,Sc,Y‐rich oxides, Y‐rich perovskite, Zr,Sc,Y‐rich pyroxenes (Al,Ti‐diopside, Sc‐rich pyroxene), and gehlenite. 3N‐24’s UR oxides and Zr,Sc‐rich Al,Ti‐diopsides are ¹⁶O‐poor (Δ¹⁷O approximately ?2‰ to ?5‰). Spinel in 3N‐24 and spinel and Al‐diopside in the FoB CAI are ¹⁶O‐rich (Δ¹⁷O approximately ?23 ± 2‰). 33E‐1’s UR oxides and Zr,Sc‐rich Al,Ti‐diopsides are ¹⁶O‐depleted (Δ¹⁷O approximately ?2‰ to ?5‰) vs. Al,Ti‐diopside of the FTA CAI and spinel (Δ¹⁷O approximately ?23 ± 2‰), and Wark‐Lovering rim Al,Ti‐diopside (Δ¹⁷O approximately ?7‰ to ?19‰). We infer that the inclusions experienced multistage formation in nebular regions with different oxygen‐isotope compositions. 3N‐24 and 33E‐1’s precursors formed by evaporation/condensation above 1600 °C. 3N and 33E’s precursors formed by condensation and melting (3N only) at significantly lower temperatures. 3N‐24 and 3N’s precursors aggregated into a compound object and experienced partial melting and thermal annealing. 33E‐1 and 33E avoided melting prior to and after aggregation. They acquired Wark‐Lovering and common forsterite‐rich accretionary rims, probably by condensation, followed by thermal annealing. We suggest 3N‐24 and 33E‐1 originated in a ¹⁶O‐rich gaseous reservoir and subsequently experienced isotope exchange in a ¹⁶O‐poor gaseous reservoir. Mechanism and timing of oxygen‐isotope exchange remain unclear.  相似文献   

Analysis of lateral loading of pile groups using embedded beam elements with interaction surface     

Diego F. Turello  Federico Pinto  Pablo J. Sánchez 《国际地质力学数值与分析法杂志》2019,43(1):272-292

The numerical simulation of soil-pile interaction problems, by means of full 3D finite element models, involves a large number of degrees of freedom (DOF) and difficulties during the mesh generation process. In order to reduce the unknowns and simplify and properly analyze such class of geotechnical problems, the so-called embedded beam elements (EBE) have recently been developed. In a preceding contribution of the authors, an improved EBE formulation, which brings into play the soil-pile interaction surface, was proposed with the aim to localize material plasticity in the soil surrounding the pile. This embedded beam model couples two different finite elements, each described by distinct kinematics (ie, solid and beam). The coupling is incorporated in the formulation by means of kinematical constrains established over the solid and beam displacement fields on the interaction surface. One of the main advantages of the embedded elements is that the addition of beams structural members immersed within the 3D soil model does not represent a constraint for the solid mesh, which can be adopted independently from the beam mesh. In this paper, the lateral loading of pile groups is studied by means of the proposed EBE approach with elasto-plastic interfaces. In order to represent a rigid cap, a master node and a special set of kinematical restrictions are incorporated into the formulation. The paper presents results obtained by means of the present formulation compared against other well-established analysis methods and test results published in the literature, for both elastic and elasto-plastic cases.  相似文献   

Ardières-Morcille in the Beaujolais,France: A research catchment dedicated to study of the transport and impacts of diffuse agricultural pollution in rivers     

Véronique Gouy  Lucie Liger  Samira Ahrouch  Chloé Bonnineau  Nadia Carluer  Arnaud Chaumot  Marina Coquery  Aymeric Dabrin  Christelle Margoum  Stéphane Pesce 《水文研究》2021,35(10):e14384

The 8-km² Morcille catchment, which is a sub-catchment of the 150-km² Ardières catchment in the Beaujolais region of France, is one of the first sites in Europe where research has been conducted on surface water contamination by pesticides. A consolidated hydrological and chemical dataset has been set up with data collected since 2002 on the Morcille River and since 2011 on the Ardières River. Additional data on the ecotoxicological and ecological impacts of pesticides on aquatic microbial communities and macroinvertebrates has also been recorded in both rivers since 2005. The ‘Site Atelier Ardières-Morcille Dataset’ described here combines rainfall and stream water height measurements at gauged stations with concentrations of two trace elements and nine pesticides (mainly herbicides, fungicides and some of their metabolites) in both the Ardières and Morcille rivers. All contaminant concentration data showed spatial and temporal variability in water quality associated with pesticide use and rainfall patterns. This long-term monitoring framework made it possible to estimate the persistence of two herbicides (diuron and norflurazon) after legislation banning them. It took 4 years for diuron and more than 10 years for norflurazon concentrations to fall below 0.1 μg/L. Concurrent biological data showed a gradient of impacts consistent with chemical anthropogenic pressure, and rapid recovery of phototrophic microbial communities after the diuron ban. Finally, monitoring data on pesticide transport in a grassed strip set on a slope of the Morcille catchment confirmed that vegetative filter strips can effectively reduce diuron fluxes in surface runoff (>80% abatement) and infiltration water (>70% abatement). The full dataset offers a valuable resource for the validation of hydrological models and the development of global approaches to better understand the pressure–transport–exposure–impact chain and aquatic community resilience at the small catchment scale.  相似文献   

Dynamic implications of ridges on a debris avalanche deposit at Tutupaca volcano (southern Peru)     

Patricio Valderrama  Olivier Roche  Pablo Samaniego  Benjamin van Wyk de Vries  Karine Bernard  Jersy Mariño 《Bulletin of Volcanology》2016,78(2):14

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Using a Mesoscale Meteorological Model to Reduce the Effect of Tropospheric Water Vapour from DInSAR Data: A Case Study for the Island of Tenerife, Canary Islands     

Antonio Eff-Darwich  Juan C. Pérez  José Fernández  Bego?a García-Lorenzo  Albano González  Pablo J. González 《Pure and Applied Geophysics》2012,169(8):1425-1441

Measurements of ground displacement through classical Differential Interferometric SAR (DInSAR) and advanced DInSAR techniques have been carried out over the entire actively volcanic island of Tenerife, Canary Islands. However, a detailed analysis of the effect of tropospheric water vapour on DInSAR at Tenerife should be carried out to evaluate its influence, including correction models that might improve the accuracy of DInSAR derived deformation signals. Unlike water vapour correction models that are based on space platforms (e.g. MODIS and MERIS), we present an alternative approach that is based on precise water vapour estimations derived from mesoscale numerical meteorological models, in particular the Weather Research and Forecasting (WRF) model. The application of this approach to a set of DInSAR observations of the island of Tenerife shows encouraging results.  相似文献   

Mercury levels in feathers of Magellanic penguins     

Frias JE  Gil MN  Esteves JL  García Borboroglu P  Kane OJ  Smith JR  Boersma PD 《Marine pollution bulletin》2012,64(6):1265-1269

Feathers are useful to determine mercury (Hg) contamination. We evaluated the mercury concentration in feathers of Magellanic penguins (Spheniscus magellanicus) age 1.5 years to 25 years at Punta Tombo, Argentina before and during their molt. Mercury ranged between <1.4 and 367 ng/g dry weight, with three extreme high values (8996 ng/g, 3011 ng/g and 1340 ng/g) all in young adults. The median concentration was lowest for juveniles and significantly higher for adults but with high variation among older adults. Males and females had similar mercury loads. Compared with other penguin species, concentrations in Magellanic penguins were low. Mercury levels for Magellanic penguins in the Southwest Atlantic for older adults averaged 206±98 ng/g, and serve as a baseline for biomonitoring and/or ecotoxicological studies.  相似文献   

Three-dimensional hydrodynamical simulations of the large-scale structure of W50−SS433     

Jesús Zavala †  Pablo F. Velázquez  Adriano H. Cerqueira  Gloria M. Dubner ‡ 《Monthly notices of the Royal Astronomical Society》2008,387(2):839-844

We present 3D hydrodynamical simulations of a precessing jet propagating inside a supernova remnant (SNR) shell, particularly applied to the W50−SS433 system in a search for the origin of its peculiar elongated morphology. Several runs were carried out with different values for the mass-loss rate of the jet, the initial radius of the SNR, and the opening angle of the precession cone. We found that our models successfully reproduce the scale and morphology of W50 when the opening angle of the jets is set to 10° or if this angle linearly varies with time. For these models, more realistic runs were made considering that the remnant is expanding into an interstellar medium with an exponential density profile (as H  i observations suggest). Taking into account all these ingredients, the large-scale morphology of the W50−SS433 system, including the asymmetry between the lobes (formed by the jet–SNR interaction), is well reproduced.  相似文献   

Coupling eruption and tsunami records: the Krakatau 1883 case study,Indonesia     

Raphaël Paris  Patrick Wassmer  Franck Lavigne  Alexander Belousov  Marina Belousova  Yan Iskandarsyah  Mhammed Benbakkar  Budianto Ontowirjo  Nelly Mazzoni 《Bulletin of Volcanology》2014,76(4):1-23

The well-documented 1883 eruption of Krakatau volcano (Indonesia) offers an opportunity to couple the eruption’s history with the tsunami record. The aim of this paper is not to re-analyse the scenario for the 1883 eruption but to demonstrate that the study of tsunami deposits provides information for reconstructing past eruptions. Indeed, though the characteristics of volcanogenic tsunami deposits are similar to those of other tsunami deposits, they may include juvenile material (e.g. fresh pumice) or be interbedded with distal pyroclastic deposits (ash fall, surges), due to their simultaneity with the eruption. Five kinds of sedimentary and volcanic facies related to the 1883 events were identified along the coasts of Java and Sumatra: (1) bioclastic tsunami sands and (2) pumiceous tsunami sands, deposited respectively before and during the Plinian phase (26–27 August); (3) rounded pumice lapilli reworked by tsunami; (4) pumiceous ash fall deposits and (5) pyroclastic surge deposits (only in Sumatra). The stratigraphic record on the coasts of Java and Sumatra, which agrees particularly well with observations of the 1883 events, is tentatively linked to the proximal stratigraphy of the eruption.  相似文献   

Comparison of Recharge Estimation Methods During a Wet Period in a Karst Aquifer          下载免费PDF全文

Carolina Guardiola‐Albert  Sergio Martos‐Rosillo  Eulogio Pardo‐Igúzquiza  Juan José Durán Valsero  Antonio Pedrera  Pablo Jiménez‐Gavilán  Cristina Liñán Baena 《Ground water》2015,53(6):885-895

Management of water resources, implying their appropriate protection, calls for a sound evaluation of recharge. Such assessment is very complex in karst aquifers. Most methods are developed for application to detrital aquifers, without taking into account the extraordinary heterogeneity of porosity and permeability of karst systems. It is commonly recommended to estimate recharge using multiple methods; however, differences inherent to the diverse methods make it difficult to clarify the accuracy of each result. In this study, recharge was estimated in a karst aquifer working in a natural regime, in a Mediterranean‐type climate, in the western part of the Sierra de las Nieves (southern Spain). Mediterranean climate regions are characterized by high inter‐annual rainfall variability featuring long dry periods and short intense wet periods, the latter constituting the most important contribution to aquifer water input. This paper aims to identify the methods that provide the most plausible range of recharge rate during wet periods. Six methods were tested: the classical method of Thornthwaite‐Mather, the Visual Balan code, the chloride balance method, and spatially distributed methods such as APLIS, a novel spatiotemporal estimation of recharge, and ZOODRM. The results help determine valid methods for application in the rest of the unit of study and in similar karst aquifers.  相似文献   

Geophysical Exploration of Fractured-Media Aquifers at the Mexican Mesa Central: Satellite City,San Luis Potosí, Mexico     

Héctor López Loera  José Alfredo Ramos Leal  Pablo Dávila Harris  David Ernesto Torres Gaytan  Victor Julian Martinez Ruiz  Avto Gogichaishvili 《Surveys in Geophysics》2015,36(1):167-184

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