Magnetic fabric of Pleistocene continental clays from the hanging-wall of an active low-angle normal fault (Altotiberina Fault,Italy)     

Marco Maffione  Stefano Pucci  Leonardo Sagnotti  Fabio Speranza 《International Journal of Earth Sciences》2012,101(3):849-861

Anisotropy of magnetic susceptibility (AMS) represents a valuable proxy able to detect subtle strain effects in very weakly deformed sediments. In compressive tectonic settings, the magnetic lineation is commonly parallel to fold axes, thrust faults, and local bedding strike, while in extensional regimes, it is perpendicular to normal faults and parallel to bedding dip directions. The Altotiberina Fault (ATF) in the northern Apennines (Italy) is a Plio-Quaternary NNW–SSE low-angle normal fault; the sedimentary basin (Tiber basin) at its hanging-wall is infilled with a syn-tectonic, sandy-clayey continental succession. We measured the AMS of apparently undeformed sandy clays sampled at 12 sites within the Tiber basin. The anisotropy parameters suggest that a primary sedimentary fabric has been overprinted by an incipient tectonic fabric. The magnetic lineation is well developed at all sites, and at the sites from the western sector of the basin it is oriented sub-perpendicular to the trend of the ATF, suggesting that it may be related to extensional strain. Conversely, the magnetic lineation of the sites from the eastern sector has a prevailing N–S direction. The occurrence of triaxial to prolate AMS ellipsoids and sub-horizontal magnetic lineations suggests that a maximum horizontal shortening along an E–W direction occurred at these sites. The presence of compressive AMS features at the hanging-wall of the ATF can be explained by the presence of gently N–S-trending local folds (hardly visible in the field) formed by either passive accommodation above an undulated fault plane, or rollover mechanism along antithetic faults. The long-lasting debate on the extensional versus compressive Plio-Quaternary tectonics of the Apennines orogenic belt should now be revised taking into account the importance of compressive structures related to local effects.  相似文献   

Marbles and carbonate rocks from central Morocco: a petrographic,mineralogical and geochemical study     

Francesca Origlia  Elisabetta Gliozzo  Anna Gandin  Marco Meccheri  Jorge E. Spangenberg  Isabella Turbanti Memmi 《Environmental Earth Sciences》2012,66(1):209-222

Petrographic, mineralogical, and stable isotopes (δ¹³C, δ¹⁸O values) compositions were used to characterise marbles and sedimentary carbonate rocks from central Morocco, which are considered to be a likely source of ornamental and building material from Roman time to the present day. This new data set was used in the frame of an archaeometric provenance study on Roman artefacts from the town of Thamusida (Kenitra, north Morocco), to assess the potential employment of these rocks for the manufacture of the archaeological materials. A representative set of samples from marbles and other carbonate rocks (limestone, dolostone) were collected in several quarries and outcrops in the Moroccan Meseta, in a region extending from the Meknes–Khenifra alignment to the Atlantic Ocean. All the samples were studied using a petrographic, mineralogical and geochemical methods. The petrographic and minerological investigations (optical microscopy, electron microscopy, X-ray diffraction) allowed to group the carbonate rocks in limestones, foliated limestone, diagenetic breccias and dolostone. The limestones could be further grouped as mudstones, wackestones–packstones, crinoid grainstones, oolitic grainstone and floatstones. Textural differences allowed to define marbles varieties. The stable carbon and oxygen isotope composition proved to be quite useful in the discrimination of marble sources, with apparently less discriminatory potential for carbonate rocks.  相似文献   

Geochemical modeling and low-frequency geoelectrical methods to evaluate the impact of an open dump in arid and deltaic environments     

Francisco?Javier?Gómez-Puentes  Marco?Antonio?Pérez-Flores  Jaime?Alonso?Reyes-LópezEmail author  Dina?L.?Lopez  Fernando?Herrera-Barrientos  Rafael?Onofre?García-Cueto  Socorro?Romero-Hernández  Fernando?Amílcar?Solís-Domínguez  Miguel?Martín-Loeches Garrido 《Environmental Earth Sciences》2016,75(13):1062

In Mexico, open dumps that are maintained by the municipality but provide no covering of waste are not uncommon. Further, disposal at these sites is often performed by burning. The aim of this study was to determine the leachate plume from an open dump located in a depositional deltaic environment, with arid climate, low rainfall and where the water table is about 2 m below the surface. The methodology comprised analysis of groundwater monitoring wells and geophysical and geochemical prospecting techniques. The 3D geoelectric interpretation shows a typical area of these depositional environments with low resistive values (10–20 Ω-m) associated with the presence of sands and clays interbedded. However, there is a very low resistivity zone associated with the dump’s impact which reaches values below 5 Ω-m, and it is located where the disposal and burning of wastes occurred. Another zone with values above 16 Ω-m appears as a limit for the advance of the saline. This is interpreted as a sandy lenses area. These sandy lenses with higher porosity transport aquifer’s water. Thus the dump is in direct contact by this conduct with clean groundwater. Piper diagrams constructed with the chemical data analysis reveal that the groundwater in the area corresponds to the chlorinated and/or sulfated sodium type, showing the impact caused by the dump. The monitoring well (NP8, on-site) with the highest dissolved solids content behaves anomalously and belongs to the more conductive zone according to the geoelectric profiles. The subsoil geochemical behavior is influenced by the seasonal water table variations provoking the dissolution of burned and unburned wastes, but the effects of slow flows in the direction of the regional flow are not discarded. Although the most impacted area within the dump is characterized to a depth of 10 m, there is a slow flow in the direction of the regional flow that has been moving pollutants out of the dumpsite during its almost 20 years of operation. The results of this study provide valuable information for the authorities to carry out an appropriate restoration project.  相似文献   

Drones as tools for monitoring beach topography changes in the Ligurian Sea (NW Mediterranean)     

Elisa Casella  Alessio Rovere  Andrea Pedroncini  Colin P. Stark  Marco Casella  Marco Ferrari  Marco Firpo 《Geo-Marine Letters》2016,36(2):151-163

The aim of this study was to evaluate topographic changes along a stretch of coastline in the Municipality of Borghetto Santo Spirito (Region of Liguria, Italy, north-western Mediterranean) by means of a remotely piloted aircraft system coupled with structure from motion and multi-view stereo techniques. This sector was surveyed three times over 5 months in the fall–winter of 2013–2014 (1 November 2013, 4 December 2013, 17 March 2014) to obtain digital elevation models and orthophotos of the beach. Changes in beach topography associated with storm action and human activities were assessed in terms of gain/loss of sediments and shifting of the wet–dry boundary defining the shoreline. Between the first and second surveys, the study area was hit by two storms (10–11 November 2013 and 21–22 November 2013) with waves approaching from the E–NNE, causing a shoreline retreat which, in some sectors, reached 7 m. Between the second and third surveys, by contrast, four storms (25–27 December 2013, 5–6 January 2014, 17–18 January 2014 and 6–10 February 2014) with waves propagating from the SE produced a general advancement of the shoreline (up to ~5 m) by deposition of sediments along some parts of the beach. The data also reflect changes in beach topography due to human activity during the 2013 fall season, when private beach managers quarried ~178 m³ of sediments on the emerged beach near the shoreline to accumulate them landwards. The results show that drones can be used for regular beach monitoring activities, and that they can provide new insights into the processes related to natural and/or human-related topographic beach changes.  相似文献   

Waterflood management using two-stage optimization with streamline simulation   总被引：1，自引：0，他引：1  

Tailai Wen  Marco R. Thiele  David Echeverría Ciaurri  Khalid Aziz  Yinyu Ye 《Computational Geosciences》2014,18(3-4):483-504

Waterflooding is a common secondary oil recovery process. Performance of waterfloods in mature fields with a significant number of wells can be improved with minimal infrastructure investment by optimizing injection/production rates of individual wells. However, a major bottleneck in the optimization framework is the large number of reservoir flow simulations often required. In this work, we propose a new method based on streamline-derived information that significantly reduces these computational costs in addition to making use of the computational efficiency of streamline simulation itself. We seek to maximize the long-term net present value of a waterflood by determining optimal individual well rates, given an expected albeit uncertain oil price and a total fluid injection volume. We approach the optimization problem by decomposing it into two stages which can be implemented in a computationally efficient manner. We show that the two-stage streamline-based optimization approach can be an effective technique when applied to reservoirs with a large number of wells in need of an efficient waterflooding strategy over a 5 to 15-year period.  相似文献   

Hydrological Regime and Renewal Capacity of the Micro-tidal Lesina Lagoon,Italy   总被引：1，自引：0，他引：1  

Christian Ferrarin  Luca Zaggia  Elio Paschini  Tommaso Scirocco  Giuliano Lorenzetti  Marco Bajo  Pierluigi Penna  Matteo Francavilla  Raffaele D’Adamo  Stefano Guerzoni 《Estuaries and Coasts》2014,37(1):79-93

A multidisciplinary approach that combines field measurements, artificial neural networks, water balance analyses and hydrodynamic modelling was developed to investigate the water budget and renewal capacity of semi-closed coastal systems. The method was applied to the Lesina Lagoon, a micro-tidal lagoon in the southern Adriatic Sea (Italy). Surface water flux between the lagoon and the sea was determined by neural network prediction and used as input in the analysis. Strong seasonal variations in the water budget equation were predicted. Fresh water inputs estimated by the water balance analysis were used as forcing by a calibrated finite element model to describe the water circulation and transport time scale of the lagoon’s surface waters. The model highlighted the spatial heterogeneity of the renewal behaviour of the system, with a strong east–west water renewal time gradient. Knowledge of spatial distribution of water renewal times is crucial for understanding the lagoon’s renewal capacity and explaining the high spatial variability of the biogeochemistry of the Lesina Lagoon.  相似文献   

Accurate 3D surface measurement of mountain slopes through a fully automated image-based technique   总被引：1，自引：1，他引：0  

Mattia Previtali  Luigi Barazzetti  Marco Scaioni 《Earth Science Informatics》2014,7(2):109-122

In this paper an automated procedure for surface reconstruction that can be used for surveying and monitoring rock and ground slopes is presented. This method has been developed for geological and engineering applications, where accuracy and completeness are factors of primary importance for the final 3D model, which must provide a detailed metric survey and not only a visual reconstruction of the scene. The proposed procedure integrates two image matching techniques. The first one is used to automatically extract a set of tie points that are needed for computing the exterior orientation parameters of all images through a photogrammetric bundle adjustment. Such tie oints are also exploited to obtain a preliminary seed model that is then enriched based on Multi-photo Least Squares Matching. During this second stage, the surface model is improved in terms of point density and accuracy. Different strategies were implemented to successfully combine both techniques, along with some new improvements. The presented procedure has been tested in two different applications: geometric modelling of rock cliffs and evaluation of weathering of a ground slope. In both cases the obtained results presented accuracy sufficient for geological investigation. Moreover, outcomes were comparable to the ones from laser scanning surveying and other photogrammetric implementations.  相似文献   

Photons motion in charged Anti-de Sitter black holes     

J. R. Villanueva  Joel Saavedra  Marco Olivares  Norman Cruz 《Astrophysics and Space Science》2013,344(2):437-446

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First record of Ostreopsis cfr. ovata on macroalgae in the Northern Adriatic Sea     

Monti M  Minocci M  Beran A  Ivesa L 《Marine pollution bulletin》2007,54(5):598-601

Ostreopsis ovata is an epiphytic potentially toxic dinoflagellate. It has a world-wide distribution, normally associated with other epiphytic or benthic dinoflagellates. In tropical seas O. ovata is often associated with the genera Gambierdiscus, Coolia and Prorocentrum, causing cinguatera fish poisoning. Recently, Ostreopsis spp. blooms in the Tyrrhenian and southern Adriatic Sea have been related to human health problems, such as breathing and skin irritation. Here we report the first record of Ostreopsis cfr. ovata in the Northern Adriatic Sea. O. cfr. ovata was isolated from macroalgae in two areas, the Gulf of Trieste (Italy) and close to Rovinj (Croatia). The microalga was identified by scanning electron microscopy and by fluorescence light microscopy. Size range and thecal pore structure were similar to those described for O. cfr. ovata in previous studies. Ostreopsis cfr. ovata was present on all the macroalgae collected, particularly browns and reds. The microalgal association on macroalgae was mostly composed of Ostreopsis sp., Coolia monotis and Coscinodiscus sp.  相似文献   

The cool surfaces of binary near-Earth asteroids     

Marco Delbo  Kevin Walsh  Alan W. Harris 《Icarus》2011,212(1):138-148

Here we show results from thermal-infrared observations of km-sized binary near-Earth asteroids (NEAs). We combine previously published thermal properties for NEAs with newly derived values for three binary NEAs. The η value derived from the near-Earth asteroid thermal model (NEATM) for each object is then used to estimate an average thermal inertia for the population of binary NEAs and compared against similar estimates for the population of non-binaries. We find that these objects have, in general, surface temperatures cooler than the average values for non-binary NEAs as suggested by elevated η values. We discuss how this may be evidence of higher-than-average surface thermal inertia. This latter physical parameter is a sensitive indicator of the presence or absence of regolith: bodies covered with fine regolith, such as the Earth’s moon, have low thermal inertia, whereas a surface with little or no regolith displays high thermal inertia. Our results are suggestive of a binary formation mechanism capable of altering surface properties, possibly removing regolith: an obvious candidate is the YORP effect.We present also newly determined sizes and geometric visible albedos derived from thermal-infrared observations of three binary NEAs: (5381) Sekhmet, (153591) 2001 SN₂₆₃, and (164121) 2003 YT₁. The diameters of these asteroids are 1.41 ± 0.21 km, 1.56 ± 0.31 km, and 2.63 ± 0.40 km, respectively. Their albedos are 0.23 ± 0.13, 0.24 ± 0.16, and 0.048 ± 0.015, respectively.  相似文献