Tethyan versus Iberian extension during the Cretaceous period in the Eastern Iberian Peninsula: insights from magnetic fabrics

This work investigates how anisotropy of magnetic susceptibility (AMS) recorded the strain related to the Early Cretaceous extensional processes in synrift sediments of the Maestrat basin (eastern Spain). Forty-two sites, distributed throughout the Lower Cretaceous sequence with dominant gentle dips, were sampled. Minerals contributing to the AMS are mainly phyllosilicates. The parallelism between magnetic and sedimentary foliation seems to indicate that a primary (synsedimentary and early diagenetic) magnetic fabric was preserved at 84% of sites. Consequently, preferred orientations of magnetic lineations are interpreted to record the effect of extensional processes coeval with sedimentation and diagenesis during this period. At these 35 sites, two main magnetic lineation orientations are found, delimiting two large domains: a NE–SW orientation prevailing in the NW sector of the basin (parallel to the extension direction of the Iberian basin), and NW–SE to NNW–SSE orientations to the SE (parallel to the extension direction controlling the western Tethys margin). Directional variability demonstrates that the Maestrat basin is located at the boundary between two domains (Iberian and Tethyan) undergoing different plate-scale extensional processes. The subsequent Cenozoic tectonic inversion affected the synsedimentary magnetic fabrics at only a few sites at the borders of the basin, where compressive features are more developed

Transition from Diffusive to Localized Regimes in Surface Corrugated Optical Waveguides

Exact calculations of the transmittance of surface corrugated optical waveguides are presented. The elastic scattering of diffuse light or other electromagnetic waves from a rough surface induces a diffusive transport along the waveguide axis. As the length of the corrugated part of the waveguide increases, a transition from the diffusive to the localized regime is observed. This involves an analogy with electron conduction in nanowires, and hence, a concept analogous to that of ``resistance'' can be introduced. We show an oscillatory behavior of both the elastic mean free path and the localization length versus the wavelength.Comment: 3 pages, REVTEX, 3 PS figure

Reflection and transmission of waves in surface-disordered waveguides

The reflection and transmission amplitudes of waves in disordered multimode waveguides are studied by means of numerical simulations based on the invariant embedding equations. In particular, we analyze the influence of surface-type disorder on the behavior of the ensemble average and fluctuations of the reflection and transmission coefficients, reflectance, transmittance, and conductance. Our results show anomalous effects stemming from the combination of mode dispersion and rough surface scattering: For a given waveguide length, the larger the mode transverse momentum is, the more strongly is the mode scattered. These effects manifest themselves in the mode selectivity of the transmission coefficients, anomalous backscattering enhancement, and speckle pattern both in reflection and transmission, reflectance and transmittance, and also in the conductance and its universal fluctuations. It is shown that, in contrast to volume impurities, surface scattering in quasi-one-dimensional structures (waveguides) gives rise to the coexistence of the ballistic, diffusive, and localized regimes within the same sample.Comment: LaTeX (REVTeX), 12 pages with 14 EPS figures (epsf macro), minor change

Intensity Distribution of Modes in Surface Corrugated Waveguides

Exact calculations of transmission and reflection coefficients in surface randomly corrugated optical waveguides are presented. As the length of the corrugated part of the waveguide increases, there is a strong preference to forward coupling through the lowest mode. An oscillating behavior of the enhanced backscattering as a function of the wavelength is predicted. Although the transport is strongly non isotropic, the analysis of the probability distributions of the transmitted waves confirms in this configuration distributions predicted by Random Matrix Theory for volume disorder

High-resolution aeromagnetic survey of Calabria (Southern Italy)

We present a 1:350,000 high-resolution magnetic anomaly map of Calabria (Southern Italy), obtained by merging the results from two low-altitude aeromagnetic surveys performed in southern and northern Calabria. Magnetic anomalies of Calabria are of low intensity, and mostly range from 11 to –9 nT. Northern Calabria is characterized by positive anomalies in the Tyrrhenian margin (Coastal Chain) that turn into negative values moving eastward in the Sila Massif. Southern Calabria is characterized by slightly positive anomaly values, interrupted by a null magnetic anomaly corridor roughly corresponding to the eastern margin of the Gioia Tauro basin. Finally, anomaly values turn systematically negative in the Messina Straits. Due to the unprecedented resolution (low flying height, spatial sampling along the flight line of ∼5 m and 1–2 km flight line spacing), the new map highlights, in detail, the geometry and setting of the upper crustal features. As Calabria is one of the most seismically active regions in Italy, hit by several high-magnitude earthquakes in recent centuries, the interpretation of this new map will hopefully contribute to new insights into the crustal geological setting, location and dimension of the main seismogenic sources.Published116-1231A. Geomagnetismo e Paleomagnetismo3SR. AMBIENTE - Servizi e ricerca per la SocietàJCR Journa

Geological reconstruction in the area of maximum co-seismic subsidence during the 2009 Mw=6.1 L’Aquila earthquake using geophysical analyses and borehole stratigraphy.

InSAR images showed that the 2009 Mw=6.1 normal faulting L'Aquila earthquake (Abruzzi region, central Italy) produced a maximum co-seismic subsidence of ca. 24 cm in the epicentral area. We report new results about the stratigraphic architecture of this area by means of the integration of geophysical and stratigraphic data from a new 151 m deep borehole. According to the indication of preliminary geophysical (electrical resistivity tomography and seismic noise) surveys, the borehole was drilled where maximum thicknesses of fine-grained sediments were expected. The geophysical results were also useful to estimate the basin substrate depth and to define the geometry of the continental deposits, successively constrained by the core stratigraphy. The core is characterized by two sequences separated by an erosional discontinuity. The upper sequence is composed by silty, sandy and gravelly deposits, mainly characterized by high values of electrical resistivity. The lower sequence is characterized by prevalence of grey clayey silt and sandy sediments, with low values of resistivity. Based on correlations among the stratigraphic core and outcrop data of the Aterno Valley, we interpret the upper sequence as related to fluvial-alluvial depositional environment during Middle Pleistocene-Holocene, whereas the lower sequence is related to deposition in a prevalent marshy floodplain environment during Early Pleistocene.Published350-3621A. Geomagnetismo e PaleomagnetismoJCR Journalrestricte

Layer parallel shortening and tectonic transport direction inferred by the anisotropy of magnetic susceptibility (AMS) from Central-Pyrenees post-hercynian rocks, Aragón-Subordán valley, Pirineo Oscense

A N-S section has been studied in post-hercynian rocks of a Central Pyrenees sector in order to search for a relationship between magnetic fabric (ASM) and the regional deformation pattern. The section, which is normal to the main ESE-WNW macrostructures, comprises materials from Upper Cretaceous to Eocene (nine sites, 253 samples). Two main types of stretching lineations have been interpreted from the ASM fabrics: The first one is defined by a magnetic lineation parallel to the major structures and interpreted by layer-parallel shortening. The second one is normal to the bedding-cleavage intersection lineation and thus coincides with the regional tectonic transport direction. Both magnetic lineations fit into the bedding surface and them are not related with the regional cleavage, suggesting its early acquisitio

Caracterización del plegamiento oblicuo del autóctono de la cuenca del Ebro a partir del análisis de fábricas magnéticas.

El análisis de la geometría y cinemática de estructuras oblicuas es necesario para entender su origen y evolución. En este trabajo el estudio de la fábrica magnética se utiliza como una herramienta para determinar la historia deformacional de los pliegues oblicuos situados en el autóctono deformado del sector nororiental de la cuenca de antepaís del Ebro. Un total de 149 estaciones han sido analizadas a partir del análisis de la fábrica magnética (anisotropía de la susceptibilidad magnética) con este objetivo. El muestreo se realizó en materiales detríticos sinorogénicos del Eoceno Superior-Oligoceno del sector de Artesa de Segre-Cardona. A pesar de la dirección de acortamiento regional aproximada N-S, oblicua con respecto a la orientación N045E a N135E de los pliegues estudiados, las direcciones obtenidas de la lineación magnética en la mayoría de los casos se encuentran contenidas en el plano de estratificación y paralelas a los ejes de los pliegues oblicuos. El análisis paleomagnético realizado de forma paralela a este estudio muestra la existencia de rotaciones anti-horarias de estos pliegues relacionadas con el emplazamiento del saliente de cabalgamientos del Pirineo Central (Peigney et al., 2021), lo que sugiere que los elipsoides magnéticos obtenidos han actuado como marcadores pasivos de la deformación registrando información relacionada con el acortamiento paralelo a las capas inicial (layer parallel shortening) y/o su plegamiento posterio

Force, charge, and conductance of an ideal metallic nanowire

The conducting and mechanical properties of a metallic nanowire formed at the junction between two macroscopic metallic electrodes are investigated. Both two- and three-dimensional wires with a W(ide)-N(arrow)-W(ide) geometry are modelled in the free-electron approximation with hard-wall boundary conditions. Tunneling and quantum-size effects are treated exactly using the scattering matrix formalism. Oscillations of order E_F/lambda_F in the tensile force are found when the wire is stretched to the breaking point, which are synchronized with quantized jumps in the conductance. The force and conductance are shown to be essentially independent of the width of the wide sections (electrodes). The exact results are compared with an adiabatic approximation; the later is found to overestimate the effects of tunneling, but still gives qualitatively reasonable results for nanowires of length L>>lambda_F, even for this abrupt geometry. In addition to the force and conductance, the net charge of the nanowire is calculated and the effects of screening are included within linear response theory. Mesoscopic charge fluctuations of order e are predicted which are strongly correlated with the mesoscopic force fluctuations. The local density of states at the Fermi energy exhibits nontrivial behavior which is correlated with fine structure in the force and conductance, showing the importance of treating the whole wire as a mesoscopic system rather than treating only the narrow part.Comment: 23 pages, 8 figure

Argument mining: A machine learning perspective

Argument mining has recently become a hot topic, attracting the interests of several and diverse research communities, ranging from artificial intelligence, to computational linguistics, natural language processing, social and philosophical sciences. In this paper, we attempt to describe the problems and challenges of argument mining from a machine learning angle. In particular, we advocate that machine learning techniques so far have been under-exploited, and that a more proper standardization of the problem, also with regards to the underlying argument model, could provide a crucial element to develop better systems