High-precision late Aptian Pb/U age for the Punta del Barco Formation (Baqueró Group), Santa Cruz Province,Argentina     

Silvia N. Césari  Carlos O. Limarino  Magdalena Llorens  Mauro G. Passalia  Valeria Pérez Loinaze  Ezequiel I. Vera 《Journal of South American Earth Sciences》2011,31(4):426-431

The Baqueró Group holds a rich fossil flora including macrofloristic and palynological remains that characterize the Early Cretaceous vegetation of Argentina. The age of the upper part of the Group, known as Punta del Barco Formation, has been a topic of several discussions in the past. The type locality of this stratigraphic unit exposes fossiliferous tuffs together with muddy tuffs and tuffaceous sandstones beds. However, there have been no reliable age constraints for the fossil assemblages. ²⁰⁶Pb/²³⁸U analyses of zircon crystals yielded an age of 114.67 ± 0.18 Ma. This age control makes possible an improved analysis and comparison of the floras in the southern region.  相似文献   

Surface and groundwater pollution by organochlorine compounds in a typical soybean system from the south Pampa,Argentina   总被引：3，自引：0，他引：3  

Mariana Gonzalez  Karina S. B. Miglioranza  Valeria M. Shimabukuro  Orlando M. Quiroz Londoño  Daniel E. Martinez  Julia E. Aizpún  Víctor J. Moreno 《Environmental Earth Sciences》2012,65(2):481-491

Organochlorine pesticides (OCPs) use has been restricted or forbidden in Argentina since 1998 and technical endosulfan is the last currently used OCPs on the soybean-wheat production. As they persist in soil for several years after application, OCPs constitute a source of environmental pollution. This work aims to assess OCPs contamination of groundwater (Gw) and streamwater (Sw) in the Quequén Grande River watershed from south Argentinean Pampas in relation to the hydrogeological characteristics. OCPs were analyzed in Sw, Gw, surface bottom sediments, soils and borehole cutting sediments (Cs) by gas chromatograph-electron capture detector. Pesticide distribution in Cs was dependent on the characteristic of the non-saturated zone. Leached pesticides over 3 m in Cs showed the pattern: HCHs = endosulfan > chlordanes > DDTs, and from 3 to 6 m heptachlor was the main group as a consequence of the past use of this compound in the area, mainly on potato crops. Endosulfan reaches Gw during application season as well as during flooding events while a retard effect was observed for Sw. Levels of α- and β-isomers were in certain cases above national (7 ng L⁻¹) and international (3 ng L⁻¹) limits for aquatic biota protection. As the endosulfan sulfate metabolite was present in Gw and Sw and due to its high toxicity, it should be considered in the establishment of water quality criteria for human and environmental protection.  相似文献   

The notion of “distinguishability” between bulk elastic parameters on the basis of the Gibbs deformation energy     

Alessandro Pavese  Valeria Diella 《Physics and Chemistry of Minerals》2010,37(8):535-541

The present work aims in discussing a principle that distinguishes between elastic parameters sets, $ \{ \Upphi \} \equiv \{ K_{0} , \, K^{\prime}, \, V_{0} ,\ldots\} The present work aims in discussing a principle that distinguishes between elastic parameters sets, { \Upphi } o { K₀ ,  K^￠,  V₀ ,?} \{ \Upphi \} \equiv \{ K_{0} , \, K^{\prime}, \, V_{0} ,\ldots\} , on the basis of an energetic criterion: once a reference set, { \Upphi_R } \{ \Upphi_{R} \} , is given, another one can be fixed, { \Upphi _min } \left\{ {\Upphi_{ \min } } \right\} , so that they are as close as possible to each other, but yield non-equivalent deformation energy curves \Updelta G({ \Upphi } )_\textdeform \Updelta G(\{ \Upphi \} )_{\text{deform}} , i.e. they give \Updelta G({ \Upphi_R } )_\textdeform \Updelta G(\{ \Upphi_{R} \} )_{\text{deform}} and \Updelta G({ \Upphi _min } )_\textdeform \Updelta G(\{ \Upphi_{ \min } \} )_{\text{deform}} such that | \Updelta G({ \Upphi _min } )_\textdeform - \Updelta G({ \Upphi_R } )_\textdeform | 3 1×s[\Updelta G_\textdeform ]. \left| {\Updelta G(\{ \Upphi_{ \min } \} )_{\text{deform}} - \Updelta G(\{ \Upphi_{R} \} )_{\text{deform}} } \right| \ge 1\times \sigma [\Updelta G_{\text{deform}} ]. ΔG _deform, calculated using the equation of state (EoS), and its uncertainty σ[ΔG _deform], obtained by a propagation of the errors affecting { \Upphi } \{ \Upphi \} are crucial to fix which mineral assemblage forms at P–T conditions and allow one to assess the reliability of such a prediction. We explore some properties related to the principle introduced, using the average values of the elastic parameters found in literature and related uncertainties for di-octahedral mica, olivine, garnet and clinopyroxene. Two elementary applications are briefly discussed: the effect of refining V ₀ in fitting EoSs to P–V experimental data, in the case of garnet and omphacite, and the phengite 3T–2M ₁ relative stability, controlled by pressure.  相似文献   

A stratigraphic and geophysical approach to studying the deep-circulating groundwater and thermal springs, and their recharge areas, in Cimini Mountains–Viterbo area, central Italy     

Ugo Chiocchini  Fabio Castaldi  Maurizio Barbieri  Valeria Eulilli 《Hydrogeology Journal》2010,18(6):1319-1341

The stratigraphic and structural setting of the Cimini Mountains and Viterbo area of Italy has been reconstructed. The architecture of the tectonic edifice, below the Pleistocene Cimino and Vicano volcanic districts cover, is characterized by the Mesozoic–Cenozoic Tuscan Nappe and the similar Umbria-Marche Succession; both are capped by the overthrusted Ligurian Late Cretaceous–Eocene Tolfa Flysch. A shallow unconfined volcanic aquifer is separated, by a thick aquiclude, from the deep confined carbonate aquifer consisting of the Tuscan Nappe and the Umbria-Marche Succession. The volcanic aquifer hosts cold waters, whilst the carbonate aquifer hosts hot sulphate–alkaline earth waters that emerge in the thermal area of Viterbo with a temperature of 30–60°C. The recharge area of cold waters is located in the Cimini Mountains. Thermal waters of the Viterbo hot springs are derived from a circuit of waters that emerge along the River Nera near Narni (about 34 km ENE of Viterbo), with a high salinity, a temperature of 16–18°C, a sulphate–alkaline earth composition, and a discharge of 13 m³/sec, whose recharge area is located in the central pre-Apennines reliefs.  相似文献   

The effects of post-orogenic extension on different scales: an example from the Apennine–Maghrebide fold-and-thrust belt, SW Sicily     

Enrico Tavarnelli  Pietro Renda  Valeria Pasqui  Mariano Tramutoli 《地学学报》2003,15(1):1-7

ABSTRACT Many structures produced under one single deformation regime, namely extensional, contractional or strike-slip, exhibit remarkable geometrical analogies when analysed at different scales. By contrast, field examples that illustrate the scale effects on structures resulting from superimposed deformations, which were produced under different tectonic regimes, are rare. Yet the change from contraction to extension is known to occur often in the most thickened portions of the continental crust. The Apennine–Maghrebide fold-and-thrust belt of Sicily shows many examples of post-orogenic extensional deformations. Composite structures, resulting from late normal faults that offset folds and thrusts, are observed at four different scales, from regional to mesoscopic, in the south-western portion of Sicily and in the adjacent Isle of Favignana. The recognized analogies in the geometry of these composite structures may provide a key for the interpretation of the features of regional structures, whose deep geometry is often poorly constrained. Moreover, comparison of normalized displacements accommodated by contractional and extensional faults of different scales indicates that self-similarity is not unique to structures produced under single tectonic regimes.  相似文献   

Analysis of trends and sudden changes in long-term environmental data from King George Island (Antarctica): relationships between global climatic oscillations and local system response     

A. Valeria Bers  Fernando Momo  Irene R. Schloss  Doris Abele 《Climatic change》2013,116(3-4):789-803

The Western Antarctic Peninsula is one of the most rapidly warming regions on earth. It is therefore important to analyze long-term trends and inter-annual patterns of change in major environmental parameters to understand the process underlying climate change in Western Antarctica. Since many polar long-term data series are fragmented and cannot be analysed with common time series analysis tools, we present statistical approaches that can deal with missing values. We applied U-statistics after Pettit and Buishand to detect abrupt changes, dynamic factor analysis to detect functional relationships, and additive modelling to detect patterns in time related to climatic cycles such as the Southern Annular Mode and El Niño Southern Oscillation in a long-term environmental data set from King George Island (WAP), covering 20 years. Our results not only reveal sudden changes for sea surface temperature and salinity, but also clear patterns in all investigated variables (sea surface temperature, salinity, suspended particulate matter and Chlorophyll a) that can directly be related to climatic cycles. Our results complement previous findings on climate related changes in the King George Island Region and provide insight into the environmental conditions and climatic drivers of system change in the study area. Hence, our statistical analyses may prove valuable for other polar environmental data sets and contribute to a better understanding of the regional variability of climate change and its impact on coastal systems.  相似文献   

Numerical modelling of the effect of horizontal drains in centrifuge tests on soil-structure interaction in liquefiable soils     

Fasano  Gianluca  Nappa  Valeria  Özcebe  Ali Güney  Bilotta  Emilio 《Bulletin of Earthquake Engineering》2021,19(10):3895-3931

Bulletin of Earthquake Engineering - The research presented herein was carried out in the framework of the H2020 LIQUEFACT project ( http://www.LIQUEFACT.eu/ ). This paper presents the results of a...  相似文献   

Typology of detrital zircon as a key to unravelling provenance in rift siliciclastic sequences (Permo-Carboniferous of Spiti,N India)     

Valeria Caironi  Eduardo Garzanti  Dario Sciunnach 《Geodinamica Acta》2013,26(2-3):101-113

Abstract

Detrital zircon populations from Carboniferous to Permian sandstones from the Lozar Section of Spiti, northern India, were analyzed with the typology method in order to obtain complementary information on the source areas of the sediments. Zircon grains were subdivided into several groups and subgroups, according to degree of abrasion and morphological features.

First appearance of detrital zircons with distinct typologic signature within successive stratigraphic intervals provided useful data about the tectono-magmatic evolution of the northern Indian margin during Late Paleozoic rifting of Gondwana and initial opening of Neotethys. The base of the studied sequence (Lower Carboniferous Thabo Fm.) is characterized by a largely cratonic provenance, seemingly from the Indian Shield to the South. In the Upper Carboniferous Chichong Fm., first occurrence of typical zircons from anatectic granites and increasing abundance of granitoid detritus suggest rapid uplift and unroofing of anatectic rocks of probable Cambro-Ordovician age. In the lowermost Permian (Asselian) glaciomarine Ganmachidam Diamictite, euhedral detrital zircons with peculiar features, associated with Cr-rich chromian spinels and mafic to felsic volcanic rock fragments, hint at emplacement of bimodal alkaline magmatic suites. The same sources, possibly including subvolcanic bodies, continued to be eroded until final break-up, documented by the Permian Kuling Group.  相似文献   

Thinking beyond organism energy use: a trait‐based bioenergetic mechanistic approach for predictions of life history traits in marine organisms     

Gianluca Sarà  Alessandro Rinaldi  Valeria Montalto 《Marine Ecology》2014,35(4):506-515

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The interplay between basement fabric,rifting, syn-rift folding,and inversion in the Rio do Peixe Basin,NE Brazil     

Leonardo M. Pichel  Alex F. Antunes  Haakon Fossen  Barbara F. Rapozo  Emma Finch  Valeria C. Córdoba 《Basin Research》2023,35(1):61-85

The Rio do Peixe Basin is part of a series of aborted Cretaceous rifts formed within the Proterozoic Borborema Province, onshore NE Brazil in response to rifting between Africa and South America. The basin is remarkably well-imaged and comprises fault-bounded depocentres, the main ones being the NE-oriented Brejo das Freiras and the E–W-oriented Sousa half-grabens. These grabens and their bounding faults are influenced by Neoproterozoic basement shear zones and present a complex framework of secondary normal faults and folds. Recent workers also interpret large reverse faults and regional post-rift shortening driven by far-field stresses from the Andes. For those reasons, the basin represents an ideal setting to investigate the multiphase history of rift basins. We thus combine borehole-calibrated 2D and 3D seismic and magnetic data with section restoration and numerical modelling to investigate the architecture and evolution of this basin. We aim to understand: (i) the controls of the basement fabric in 3D fault architecture and kinematics and (ii) how syn-rift faults controlled the geometry and development of fault-related folds. By doing this, we also investigate the timing, kinematics, and magnitude of inversion in the basin to explore its multiphase history. We demonstrate that (i) the basement fabric controlled not only the strike of faults but also their geometry and polarity at depth, (ii) folds in the syn-rift sequence are attributed simply to syn-rift extension along stepped and/or curved faults, and (iii) inverted and/or reverse faults occur within the basin, but these are minor and appear to have formed during rifting. We explain this minor inversion by a change in plate kinematics related to the onset of the nearby transform margin to the north. These results have implications for understanding the 3D evolution of oblique grabens, the role of structural inheritance, and the recognition of inversion- versus extension-related folds in rift basins worldwide.  相似文献