Compositional gradients in large reservoirs of silicic magma as evidenced by ignimbrites versus Taylor Creek Rhyolite lava domes     

Wendell A. Duffield  Joaquin Ruiz 《Contributions to Mineralogy and Petrology》1992,110(2-3):192-210

The Taylor Creek Rhyolite of southwest New Mexico consists of 20 lava domes and flows that were emplaced during a period of a few thousand years or less in late Oligocene time. Including genetically associated pyroclastic deposits, which are about as voluminous as the lava domes and flows, the Taylor Creek Rhyolite represents roughly 100 km³ of magma erupted from vents distributed throughout an area of several hundred square kilometers. Major-element composition is metaluminous to weakly peraluminous high-silica rhyolite and is nearly constant throughout the lava field. The magma reservoir for the Taylor Creek Rhyolite was vertically zoned in trace elements, ⁸⁷Sr/⁸⁶Sr, and phenocryst abundance and size. Mean trace-element concentrations, ranges in concentrations, and element-pair correlations are similar to many subalkaline silicic ignimbrites. However, the polarity of the zonation was opposite that in reservoirs for ignimbrites, for most constituents. For example, compared to the Bishop Tuff, only ⁸⁷Sr/⁸⁶Sr and Sc increased upward in both reservoirs. Quite likely, a dominant but nonerupted volume of the magma reservoir for the Taylor Creek Rhyolite was zoned like that for the Bishop Tuff, whereas an erupted, few-hundred-meter-thick cap on the magma body was variably contaminated by roof rocks whose contribution to this part of the magma system moderated relatively extreme trace-element concentrations of uncontaminated Taylor Creek Rhyolite but did not change the sense of correlation for most element pairs. The contaminant probably was a Precambrian rock of broadly granitic composition and with very high ⁸⁷Sr/⁸⁶Sr. Although examples apparently are not yet reported in the literature, evidence for a similar thin contaminated cap on reservoirs for large-volume silicic ignimbrites may exist in the bottom few meters of ignimbrites or perhaps only in the pumice fallout that normally immediately precedes ignimbrite emplacement. ⁸⁷Sr/⁸⁶Sr in sanidine phenocrysts of the Taylor Creek Rhyolite is higher than that of their host whole rocks. Covariation of this isotope ratio with sanidine abundance and size indicates positive correlations for all three features with decreasing distance to the roof of the magma reservoir. The sanidine probably is more radiogenic than host whole rock because growing phenocrysts partly incorporated Sr from the first partial melt of roof rocks, which contained the highly radiogenic Sr of Precambrian biotite ± hornblende, whereas diffusion was too slow for sanidine to incorporate much of the Sr from subsequently produced less radiogenic partial melt of roof rocks, before eruption quenched the magma system. Disequilibrium between feldspar phenocrysts and host groundmass is fairly common for ignimbrites, and a process of contamination similar to that for the Taylor Creek Rhyolite may help explain some of these situations.  相似文献   

Species distribution modeling: a statistical review with focus in spatio-temporal issues     

Joaquín?Martínez-MinayaEmail authorView author&#;s OrcID profile  Michela?Cameletti  David?Conesa  Maria?Grazia?Pennino 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(11):3227-3244

The use of complex statistical models has recently increased substantially in the context of species distribution behavior. This complexity has made the inferential and predictive processes challenging to perform. The Bayesian approach has become a good option to deal with these models due to the ease with which prior information can be incorporated along with the fact that it provides a more realistic and accurate estimation of uncertainty. In this paper, we first review the sources of information and different approaches (frequentist and Bayesian) to model the distribution of a species. We also discuss the Integrated Nested Laplace approximation as a tool with which to obtain marginal posterior distributions of the parameters involved in these models. We finally discuss some important statistical issues that arise when researchers use species data: the presence of a temporal effect (presenting different spatial and spatio-temporal structures), preferential sampling, spatial misalignment, non-stationarity, imperfect detection, and the excess of zeros.  相似文献   

Wave height prediction in the Western Mediterranean using genetic algorithms     

B. Cañellas  S. Balle  J. Tintoré  A. Orfila 《Ocean Engineering》2010,37(8-9):742-748

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Multi-platform model assessment in the Western Mediterranean Sea: impact of downscaling on the surface circulation and mesoscale activity     

Aguiar  Eva  Mourre  Baptiste  Juza  Mélanie  Reyes  Emma  Hernández-Lasheras  Jaime  Cutolo  Eugenio  Mason  Evan  Tintoré  Joaquín 《Ocean Dynamics》2020,70(2):273-288

Ocean Dynamics - In numerical ocean modeling, dynamical downscaling is the approach consisting in generating high-resolution regional simulations exploiting the information from coarser resolution...  相似文献   

Exact seismic response of smooth rigid retaining walls resting on stiff soil     

Joaquin Garcia-Suarez  Domniki Asimaki 《国际地质力学数值与分析法杂志》2020,44(13):1750-1769

The assessment of forces exerted on walls by the backfill is a recurrent problem in geotechnical engineering, owing to its relevance for both retaining systems and underground structures. In particular, the work by Arias and colleagues, and later also the one by Veletsos and Younan, among others, becomes pertinent when considering pressure increments on underground structures triggered by seismic events. As a first step, they studied the response of a rigid retaining wall resting on rigid bedrock subjected to SV waves, introducing some simplifying assumptions. This paper presents the exact solution to this reference problem. The solution is given in horizontal wavenumber domain; hence, it comes in terms of inverse Fourier transforms, which can be approximated numerically in Mathematica, which in turn are verified against finite-element simulations. Specific features of this exact solution that were not captured by prior engineering approximations are highlighted and discussed.  相似文献   

Platinum group minerals (PGM) in the Falcondo Ni-laterite deposit,Loma Caribe peridotite (Dominican Republic)     

Thomas Aiglsperger  Joaquin A. Proenza  Federica Zaccarini  John F. Lewis  Giorgio Garuti  Manuel Labrador  Francisco Longo 《Mineralium Deposita》2015,50(1):105-123

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Civil nuclear power at risk of tsunamis     

Joaquin Rodriguez-Vidal  Jose M. Rodriguez-Llanes  Debarati Guha-Sapir 《Natural Hazards》2012,63(2):1273-1278

Tsunamis have caused severe destruction to vulnerable populations through the ages. Commonly generated from oceanic subduction zones, they still remain difficult to predict. Recent instrumental record on risk of occurrence can be enhanced when complemented by historical, archeological, and geological studies. We assessed the coast at risk and overlaid civilian nuclear sites active, in expansion and under construction. The worldwide distribution of threatened nuclear sites revealed a clustering in South and South-East Asia. We identified four areas for urgent policy attention, including the need for funding to translate scientific risks assessment into effective policy.  相似文献   

Usefulness of the temporal analysis and the normalized difference in the study of rice by means of landsat‐5 TM images: Identification and inventory of rice fields     

Maria‐Amparo Gilabert  Joaquin Melia 《国际地球制图》2013,28(4):17-26

The multispectral and multitemporal analysis of the spectral response of rice has made it possible to determine at which point in the vegetative cycle of rice it is best to make an inventory, together with the usefulness of the normalized‐difference vegetation index for such an inventory. The results could be usefully included in any classification procedure of the TM image in order to make the inventory in a systematic way. In this case a supervised classification of the image has been made which assumes a Gaussian behaviour for each spectral class. The results obtained are, for the most part, consistent with those obtained by using traditional methods.  相似文献   

Improved atmospheric circulation over Europe by the new generation of CMIP6 earth system models     

Fernandez-Granja  Juan A.  Casanueva  Ana  Bedia  Joaquin  Fernandez  Jesus 《Climate Dynamics》2021,56(11):3527-3540

Global Climate Models (GCMs) generally exhibit significant biases in the representation of large-scale atmospheric circulation. Even after a sensible bias adjustment these errors remain and are inherited to some extent by the derived downscaling products, impairing the credibility of future regional projections. In this study we perform a process-based evaluation of state-of-the-art GCMs from CMIP5 and CMIP6, with a focus on the simulation of the synoptic climatological patterns having a most prominent effect on the European climate. To this aim, we use the Lamb Weather Type Classification (LWT, Lamb British isles weather types and a register of the daily sequence 736 of circulation patterns 1861-1971. METEOROL OFF, GEOPHYS MEM; 737 GB; DA 1972; NO 116; PP 1-85; BIBL 2P1/2, 1972), a subjective classification of circulation weather types constructed upon historical simulations of daily mean sea level pressure. Observational uncertainty has been taken into account by considering four different reanalysis products of varying characteristics. Our evaluation unveils an overall improvement of salient atmospheric circulation features consistent across observational references, although this is uneven across models and large frequency biases still remain for the main LWTs. Some CMIP6 models attain similar or even worse results than their CMIP5 counterparts, although in most cases consistent improvements have been found, demonstrating the ability of the new models to better capture key synoptic conditions. In light of the large differences found across models, we advocate for a careful selection of driving GCMs in downscaling experiments with a special focus on large-scale atmospheric circulation aspects.

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Assessment of CHADFDM satellite-based input dataset for the groundwater recharge estimation in arid and data scarce regions     

Nafiseh Salehi Siavashani  Joaquin Jimenez-Martinez  Guillermo Vaquero  Francisco J. Elorza  Justin Sheffield  Lucila Candela  Aleix Serrat-Capdevila 《水文研究》2021,35(6):e14250

Aquifer natural recharge estimations are a prerequisite for understanding hydrologic systems and sustainable water resources management. As meteorological data series collection is difficult in arid and semiarid areas, satellite products have recently become an alternative for water resources studies. A daily groundwater recharge estimation in the NW part of the Lake Chad Basin, using a soil–plant-atmosphere model (VisualBALAN), from ground- and satellite-based meteorological input dataset for non-irrigated and irrigated land and for the 2005–2014 period is presented. Average annual values were 284 mm and 30°C for precipitation and temperature in ground-based gauge stations. For the satellite-model-based Lake Chad Basin Flood and Drought Monitor System platform (CHADFDM), average annual precipitation and temperature were 417 mm and 29°C, respectively. Uncertainties derived from satellite data measurement could account for the rainfall difference. The estimated mean annual aquifer recharge was always higher from satellite- than ground-based data, with differences up to 46% for dryland and 23% in irrigated areas. Recharge response to rainfall events was very variable and results were very sensitive to: wilting point, field capacity and curve number for runoff estimation. Obtained results provide plausible recharge values beyond the uncertainty related to data input and modelling approach. This work prevents on the important deviations in recharge estimation from weighted-ensemble satellite-based data, informing in decision making to both stakeholders and policy makers.  相似文献