U‐Th Zircon Dating by Laser Ablation Single Collector Inductively Coupled Plasma‐Mass Spectrometry (LA‐ICP‐MS)          下载免费PDF全文

Marcel Guillong  Jakub T. Sliwinski  Axel Schmitt  Francesca Forni  Olivier Bachmann 《Geostandards and Geoanalytical Research》2016,40(3):377-387

Zircon crystals in the age range of ca. 10–300 ka can be dated by ²³⁰Th/²³⁸U (U‐Th) disequilibrium methods because of the strong fractionation between Th and U during crystallisation of zircon from melts. Laser ablation inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analysis of nine commonly used reference zircons (at secular equilibrium) and a synthetic zircon indicates that corrections for abundance sensitivity and dizirconium trioxide molecular ions (Zr₂O₃⁺) are critical for reliable determination of ²³⁰Th abundances in zircon. When corrected for abundance sensitivity and interferences, mean activity ratios of (²³⁰Th)/(²³⁸U) for nine reference zircons analysed on five different days averaged 0.995 ± 0.023 (95% confidence weighted by data‐point uncertainty only, MSWD = 1.6; n = 9), consistent with their U‐Pb ages > 4 Ma that imply equilibrium for all intermediate daughter isotopes (including ²³⁰Th) within the ²³⁸U decay chain. U‐Th zircon ages generated by LA‐ICP‐MS without mitigating (e.g., by high mass resolution) or correcting for abundance sensitivity and molecular interferences on ²³⁰Th are potentially unreliable. To validate the applicability of LA‐ICP‐MS to this dating method, we acquired data from three late Quaternary volcanic units: the 41 ka Campanian Ignimbrite (plutonic clasts), the 161 ka Kos Plateau Tuff (juvenile clasts) and the 12 ka Puy de Dôme trachyte lava (all eruption ages by Ar/Ar, with zircon U‐Th ages being of equal or slightly older). A comparison of the corrected LA‐ICP‐MS results with previously published secondary ion mass spectrometry (SIMS) data for these rocks shows comparable ages with equivalent precision for LA‐ICP‐MS and SIMS, but much shorter analysis durations (~ 2 min vs. ~ 15 min) per spot with LA‐ICP‐MS and much simpler sample preparation. Previously undated zircons from the Yali eruption (Kos‐Nisyros volcanic centre, Greece) were analysed using this method. This yielded a large age spread (~ 45 to > 300 ka), suggesting significant antecryst recycling. The youngest zircon age (~ 45 ± 10 ka) provides a reasonable maximum estimate for the eruption age, in agreement with the previously published age using oxygen isotope stratigraphy (~ 31 ka).  相似文献   

Comparisons among the five ground-motion models developed using RESORCE for the prediction of response spectral accelerations due to earthquakes in Europe and the Middle East   总被引：5，自引：5，他引：0  

John Douglas  Sinan Akkar  Gabriele Ameri  Pierre-Yves Bard  Dino Bindi  Julian J. Bommer  Sanjay Singh Bora  Fabrice Cotton  Boumédiène Derras  Marcel Hermkes  Nicolas Martin Kuehn  Lucia Luzi  Marco Massa  Francesca Pacor  Carsten Riggelsen  M. Abdullah Sandıkkaya  Frank Scherbaum  Peter J. Stafford  Paola Traversa 《Bulletin of Earthquake Engineering》2014,12(1):341-358

This article presents comparisons among the five ground-motion models described in other articles within this special issue, in terms of data selection criteria, characteristics of the models and predicted peak ground and response spectral accelerations. Comparisons are also made with predictions from the Next Generation Attenuation (NGA) models to which the models presented here have similarities (e.g. a common master database has been used) but also differences (e.g. some models in this issue are nonparametric). As a result of the differing data selection criteria and derivation techniques the predicted median ground motions show considerable differences (up to a factor of two for certain scenarios), particularly for magnitudes and distances close to or beyond the range of the available observations. The predicted influence of style-of-faulting shows much variation among models whereas site amplification factors are more similar, with peak amplification at around 1s. These differences are greater than those among predictions from the NGA models. The models for aleatory variability (sigma), however, are similar and suggest that ground-motion variability from this region is slightly higher than that predicted by the NGA models, based primarily on data from California and Taiwan.  相似文献   

Users’ perception analysis for sustainable beach management in Italy     

Valentina Marin  Francesca Palmisani  Roberta Ivaldi  Rosanna Dursi  Mauro Fabiano 《Ocean & Coastal Management》2009,52(5):268-277

It is generally accepted that end-users’ perception is likely to play a pivotal role for planning and policy consideration. Beach user analysis is thus an important component defining beach management policies. In the framework of a wider project on beaches management, an investigation on residents and tourists was conducted. A survey conducted through questionnaires and interviews was carried out in six coastal municipalities. Results allowed obtaining a clear picture about user profile, perception of the beaches, awareness and attitude about themes related to beach management (i.e. Blue Flag award and beach nourishment practices). Their integration with the “expert knowledge” based analysis allowed to support the definition of beach management interventions.  相似文献   

Environmental impacts of household appliances in Europe and scenarios for their impact reduction     

Roland Hischier  Francesca Reale  Valentina Castellani  Serenella Sala 《Chemie der Erde / Geochemistry》2012

Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint “appliances” for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative – i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale).  相似文献   

Discussion of the Original Paper “Internal Stability Analysis of Reinforced Earth Retaining Walls” by Lazhar Belabed, Hacene Benyaghla and Jarir Yahiaoui, Geotechnical and Geological Engineering (2011) 29: 443-452, DOI 10.1007/s10706-011-9390-4     

Castorina Silva Vieira 《Geotechnical and Geological Engineering》2012,30(2):511-512

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A spectral comparison of (379) Huenna and its satellite     

Francesca E. DeMeo  Benoît Carry  Franck Marchis  Richard P. Binzel  Schelte J. Bus  Alin Nedelcu  Michael Busch 《Icarus》2011,212(2):677-681

We present near-infrared spectral measurements of Themis family Asteroid (379) Huenna (D ∼ 98 km) and its 6 km satellite using SpeX on the NASA IRTF. The companion was farther than 1.5″ from the primary at the time of observations and was approximately 5 magnitudes dimmer. We describe a method for separating and extracting the signal of a companion asteroid when the signal is not entirely resolved from the primary. The spectrum of (379) Huenna has a broad, shallow feature near 1 μm and a low slope, characteristic of C-type asteroids. The secondary’s spectrum is consistent with the taxonomic classification of C-complex or X-complex. The quality of the data was not sufficient to identify any subtle feature in the secondary’s spectrum.  相似文献   

Imposex and accumulation of organotin compounds in populations of Hexaplex trunculus (Gastropoda, Muricidae) from the Lagoon of Venice (Italy) and Istrian Coast (Croatia)     

Garaventa F  Centanni E  Pellizzato F  Faimali M  Terlizzi A  Pavoni B 《Marine pollution bulletin》2007,54(5):615-622

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Research and development of advanced technologies for landslide hazard analysis in Italy   总被引：2，自引：0，他引：2  

Francesca Bozzano  Paolo Mazzanti  Alberto Prestininzi  Gabriele Scarascia Mugnozza 《Landslides》2010,7(3):381-385

The Research Centre on Prediction, Prevention and Control of Georisks, "Sapienza Università di Roma" (CERI) was selected as one of the World Centres of Excellence on Landslide Risk Reduction (WCoE) under the title of “Research and development of advanced technologies for landslide hazard analysis in Italy” in the period 2008–2011. The present paper provides background information on the activities carried out by the CERI, in the frame of the WCoE network. Pre-defined purposes have been achieved by the implementation of integrated monitoring systems and early warning systems for landslides movements. The application of GBInSAR technique for monitoring landslides interacting with infrastructures is discussed, and two case histories are presented. It is shown that this technique is particularly suitable for the displacements monitoring of landslides interacting with infrastructures, thanks to its peculiar features (i.e. areal mapping, operability under every weather and lighting conditions and continuous and completely remote monitoring). Hence, it can be considered a very important tool for the reduction of risks connected to the realisation and activity of large infrastructures.  相似文献   

What determines galactic evolution?     

Francesca Matteucci 《Astrophysics and Space Science》2003,284(2):539-548

We are briefly introducing the most important ingredients to study galactic evolution. In particular the roles of star formation, nucleosynthesis and gas flows. Then we are discussing the two different approaches to galactic evolution: the stellar population approach (chemical evolution models) and the hierarchical clustering scenario for galaxy formation. It is shown that there are still some controversial points in the two approaches, as is evident in the brief summary of the discussion. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

CNO evolution: Milky way, dwarf galaxies and DLAs     

Cristina Chiappini  Donatella Romano  Francesca Matteucci 《Astrophysics and Space Science》2003,284(2):771-774

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