Micro-Analytical Zircon and Monazite U-Pb Isotope Dating by Laser Ablation-Inductively Coupled Plasma-Quadrupole Mass Spectrometry     

Keegan E. Alagna  Maurizio Petrelli  Diego Perugini  Giampiero Poli 《Geostandards and Geoanalytical Research》2008,32(1):103-120

In this study we evaluated the capability of a 213 nm laser ablation system coupled to a quadrupole-based ICP-MS in delivering accurate and precise U-Pb ages on zircons and monazites. Four zircon samples ( ca. 50 Ma to ca. 600 Ma) and four monazite samples ( ca. 30 Ma to ca. 1390 Ma) of known ages were analysed utilising laser ablation pits with diameters of 20 μm and 60 μm. Instrument mass bias and laser induced time-dependent elemental fractionation were corrected for by calibration against a matrix-matched reference material. Tera-Wasserburg plots of the calculated U-Pb data were employed to assess, and correct for, common Pb contributions. The results indicated that the LA-ICP-MS technique employed in this study allowed precise and accurate U-Pb isotope dating of zircon and monazite on sample areas 20 μm in diameter. At this spot size, the precisions achieved for single spot ²⁰⁶Pb/²³⁸U ages, were better than 5% (2s) for monazites and zircons with ages down to 30 Ma and 50 Ma, respectively. The precisions reported are comparable to those generally reported in SIMS and LA-MC-ICP-MS U-Pb isotope determinations.  相似文献   

The Phase A study of the ESA M4 mission candidate ARIEL     

Ludovic Puig  Göran Pilbratt  Astrid Heske  Isabel Escudero  Pierre-Elie Crouzet  Bram de Vogeleer  Kate Symonds  Ralf Kohley  Pierre Drossart  Paul Eccleston  Paul Hartogh  Jeremy Leconte  Giusi Micela  Marc Ollivier  Giovanna Tinetti  Diego Turrini  Bart Vandenbussche  Paulina Wolkenberg 《Experimental Astronomy》2018,46(1):211-239

ARIEL, the Atmospheric Remote sensing Infrared Exoplanet Large survey, is one of the three M-class mission candidates competing for the M4 launch slot within the Cosmic Vision science programme of the European Space Agency (ESA). As such, ARIEL has been the subject of a Phase A study that involved European industry, research institutes and universities from ESA member states. This study is now completed and the M4 down-selection is expected to be concluded in November 2017. ARIEL is a concept for a dedicated mission to measure the chemical composition and structure of hundreds of exoplanet atmospheres using the technique of transit spectroscopy. ARIEL targets extend from gas giants (Jupiter or Neptune-like) to super-Earths in the very hot to warm zones of F to M-type host stars, opening up the way to large-scale, comparative planetology that would place our own Solar System in the context of other planetary systems in the Milky Way. A technical and programmatic review of the ARIEL mission was performed between February and May 2017, with the objective of assessing the readiness of the mission to progress to the Phase B1 study. No critical issues were identified and the mission was deemed technically feasible within the M4 programmatic boundary conditions. In this paper we give an overview of the final mission concept for ARIEL as of the end of the Phase A study, from scientific, technical and operational perspectives.  相似文献   

Guidelines for the good practice of surface wave analysis: a product of the InterPACIFIC project     

Sebastiano Foti  Fabrice Hollender  Flora Garofalo  Dario Albarello  Michael Asten  Pierre-Yves Bard  Cesare Comina  Cécile Cornou  Brady Cox  Giuseppe Di Giulio  Thomas Forbriger  Koichi Hayashi  Enrico Lunedei  Antony Martin  Diego Mercerat  Matthias Ohrnberger  Valerio Poggi  Florence Renalier  Deborah Sicilia  Valentina Socco 《Bulletin of Earthquake Engineering》2018,16(6):2367-2420

Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the V_S,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standard to assure quality and reliability of the results. The present guidelines provide practical information on the acquisition and analysis of surface wave data by giving some basic principles and specific suggestions related to the most common situations. They are primarily targeted to non-expert users approaching surface wave testing, but can be useful to specialists in the field as a general reference. The guidelines are based on the experience gained within the InterPACIFIC project and on the expertise of the participants in acquisition and analysis of surface wave data.  相似文献   

Estimates of Horizontal Groundwater Flow Velocities in Boreholes     

Martí Bayer-Raich  Anthony Credoz  Jordi Guimerà  Salvador Jordana  Diego Sampietro  Jordi Font-Capó  Nathalie Nief  Matthieu Grossemy 《Ground water》2019,57(4):525-533

Currently, monitoring tools can be deployed in observation boreholes to better assess groundwater flow, flux of dissolved contaminants and their mass discharge in an aquifer. The relationship between horizontal water velocity in observation boreholes and Darcy fluxes in the surrounding aquifer has been studied for natural flow conditions (i.e., no pumping). Interpretation of measurements taken with dilution tests, the colloidal borescope, the Heat Pulse Flowmeter, and other techniques require the conversion of observed borehole velocity u to aquifer Darcy flux q_∞ . This conversion is typically done through a proportionality factor α = u/q_∞ . In experimental studies as well as in theoretical developments, reported values of α vary almost three orders of magnitude (from 0.5 to 10). This large variability in reported values of α could be explained by: (1) unclear distinction between Darcy flux and water seepage velocity, (2) unclear definition of water velocity in the borehole, (3) effects of well screen and the presence of the measurement device itself on the observable velocities, and (4) hydraulic conditions in the borehole annulus. We address (1), (2) from a conceptual/theoretical perspective, and (3) by means of numerical simulations. We show that issue (1) in low porosity aquifers can yield to order-of-magnitude discrepancies in estimates of q_∞ ; (2) may result in discrepancies of up to 50%, and (3) can cause differences up to 20% of water velocity in the borehole void space compared to the theoretical case of an open borehole.  相似文献   

In situ measurements of fine sediment infiltration (FSI) in gravel-bed rivers with a hydropeaking flow regime     

Christoph Hauer  Patrick Holzapfel  Diego Tonolla  Helmut Habersack  Guido Zolezzi 《地球表面变化过程与地形》2019,44(2):433-448

The overpresence of fine sediment and fine sediment infiltration (FSI) in the aquatic environment of rivers are of increasing importance due to their limiting effects on habitat quality and use. The habitats of both macroinvertebrates and fish, especially spawning sites, can be negatively affected. More recently, hydropeaking has been mentioned as a driving factor in fine sediment dynamics and FSI in gravel-bed rivers. The primary aim of the present study was to quantify FSI in the vertical stratigraphy of alpine rivers with hydropeaking flow regimes in order to identify possible differences in FSI between the permanently wetted area (during base and peak flows) and the so-called dewatering areas, which are only inundated during peak flows. Moreover, we assessed whether the discharge ratio between base and peak flow is able to explain the magnitude of FSI. To address these aims, freeze-core samples were taken in eight different alpine river catchments. The results showed significant differences in the vertical stratification of FSI between the permanently wetted area during base flow and the dewatering sites. Surface clogging occurred only in the dewatering areas, with decreasing percentages of fine sediments associated with increasing core depths. In contrast, permanently wetted areas contained little or no fine sediment concentrations on the surface of the river bed. Furthermore, no statistical relationship was observed between the magnitude of hydropeaking and the sampled FSI rate. A repeated survey of FSI in the gravel matrix revealed the importance of de-clogging caused by flooding and the importance of FSI in the aquatic environment, especially in the initial stages of riparian vegetation establishment. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

Adjustments in channel morphology due to land‐use changes and check dam installation in mountain torrents of Calabria (southern Italy)          下载免费PDF全文

Diego Fortugno  Carolina Boix‐Fayos  Giuseppe Bombino  Pietro Denisi  Juan Manuel Quiñonero Rubio  Vincenzo Tamburino  Demetrio Antonio Zema 《地球表面变化过程与地形》2017,42(14):2469-2483

In Mediterranean semi‐arid conditions, the availability of studies monitoring channel adjustments as a response to reforestation and check dams over representative observation periods, could help develop new management strategies. This investigation is an integrated approach assessing the adjustments of channel morphology in a typical torrent of southern Italy after land‐use changes and check dam construction across a period of about 60 years. A statistical analysis of historical rainfall records, an analysis of land‐use changes in the catchment area and a geomorphological mapping of channel adjustments were carried out and combined with field surveys of bed surface grain‐size over a 5‐km reach including 14 check dams. The analysis of the historical rainfall records showed a slight decrease in the amount and erosivity of precipitation. Mapping of land‐use changes highlighted a general increase of vegetal coverage on the slopes adjacent to the monitored reaches. Together with the check dam network installation, this increase could have induced a reduction in water and sediment supply. The different erosional and depositional forms and adjustments showed a general narrowing between consecutive check dams together with local modifications detected upstream (bed aggradation and cross‐section expansion together with low‐flow realignments) and downstream (local incision) of the installed check dams. Changes in the torrent bends were also detected as a response to erosional and depositional processes with different intensities. The study highlighted: the efficiency of check dams against the disrupting power of intense floods by stabilizing the active channel and the influence of reforestation in increasing hillslope protection from erosion and disconnectivity of water and sediment flows towards the active channel. Only slight management interventions (for instance, the conversion of the existing check dams into open structures) are suggested, in order to mobilize the residual sediment avoiding further generalized incision of the active channel and coast line erosion. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Video-monitoring of wood discharge: first inter-basin comparison and recommendations to install video cameras     

Hossein Ghaffarian  Hervé Piégay  Diego Lopez  Nicolas Rivière  Bruce MacVicar  Aurelie Antonio  Emmanuel Mignot 《地球表面变化过程与地形》2020,45(10):2219-2234

Wood in rivers plays a major role both ecologically and morphologically. In recent decades, due to human activities in the river channels and along the riparian zone, wood obstruction and jamming has exacerbated flooding hazards and infrastructure damage. Therefore, it is necessary to quantify the wood flux and discharge in rivers to improve wood hazard management. Among the various methods for monitoring the wood flux in a river, the streamside videography technique is effective given its high temporal and spatial resolution. Previous work monitored the wood discharge (m³/s) using this technique in the Ain River (France) during three floods (MacVicar and Piégay, 2012), and the same method is implemented on the Isère River (France) to obtain the statistics of wood discharge for two floods. Comparison between the two sites supports the generalization of both the monitoring technique and the link between wood discharge and flood characteristics. We first show that the maximum wood discharge is observed at bankfull discharge, and we confirm the three stage model proposed by MacVicar and Piégay (2012). Additionally, transverse distributions of the number of wood pieces and corresponding wood length appear to be similar for different flood magnitudes on each site. As a technical contribution, the use of the same technique on two sites allows for recommendations on key decisions related to the location and implementation of the equipment. Both statistical and technical contributions can be used by decision makers to implement this monitoring technique, acquire the wood transport parameters, and evaluate the potential wood hazards at local scale or along a river. © 2020 John Wiley & Sons, Ltd.  相似文献   

A hybrid deterministic and stochastic approach for tsunami hazard assessment in Iquique,Chile     

González  Juan  González  Gabriel  Aránguiz  Rafael  Melgar  Diego  Zamora  Natalia  Shrivastava  Mahesh N.  Das  Ranjit  Catalán  Patricio A.  Cienfuegos  Rodrigo 《Natural Hazards》2020,101(1):231-253

Natural Hazards - This paper presents an investigation of the collapse of a 325-year-old multi-tiered heritage temple during the 2015 Gorkha earthquake in Kathmandu, Nepal. The research comprises a...  相似文献   

Morphological Variation of the Sea Silverside Odontesthes regia in Regions with Dissimilar Upwelling Intensity along the Humboldt Current System     

Deville  Diego  Sanchez  Gustavo  Barahona  Sergio  Yamashiro  Carmen  Oré-Chávez  Daniel  Bazán  Roger Quiroz  Umino  Tetsuya 《Ocean Science Journal》2020,55(1):33-48

Ocean Science Journal - We evaluated the influence of areas with dissimilar upwelling intensity along the Humboldt Current System on the morphological variation of the economically important sea...  相似文献   

Three-dimensional nonlinear random wave groups in intermediate water depth     

Felice Arena  Alfredo Ascanelli  Vincenzo Nava  Diego Pavone  Alessandra Romolo 《Coastal Engineering》2008,55(12):1052-1061

High waves at ocean occur during a complex space–time evolution of wave groups. In this paper the nonlinear structure of three-dimensional sea wave groups at intermediate water depth is investigated. To this purpose, the Boccotti's Quasi-Determinism theory is firstly applied to describe the linear wave groups when a given exceptionally high crest occurs. Then, the second-order correction to the linear solution is derived for the general condition of three-dimensional wave groups, at a finite water depth. Several numerical applications, finally, have been carried out in order to show how both the spectral bandwidth and the directional spreading modify the nonlinear high waves at different water depth.  相似文献