Tectonic and sedimentary evolution of the Lower Pliocene Periadriatic foredeep in Central Italy     

Stefano Carruba  Raffaele Casnedi  Cesare R. Perotti  Milly Tornaghi  Giorgio Bolis 《International Journal of Earth Sciences》2006,95(4):665-683

The Periadriatic foredeep (Italy) was generated by Neogene downbending of the Adria Plate under the Apennine Chain. The basin is filled with Plio-Pleistocene siliciclastic turbidites. Its substratum consists of the carbonate succession of the southwestern Adria Plate margin. The influence of the basin’s morphology on sedimentation and subsequent tectonic evolution is investigated in the Abruzzo sector of the foredeep (Cellino Basin). The substratum is composed of Messinian evaporites that dip towards the Apennines (W). A NNW component along the depocentral axis is divided into four blocks with different depths. The substratum was also affected by a Messinian extensional fault system, not involving the overlying Pliocene sequence. This morphology controlled the distribution of the turbidites in the lower part of the Cellino Basin. The Plio-Pleistocene compressional deformation of the foredeep produced an inner complex structure (Internal Structure), involving the foredeep substratum and an outer imbricate thrust system (Coastal Structure), detached over the faulted Messinian evaporites. This thrust system is parallel to the extensional faults, suggesting a strong influence of the substratum morphology on the development of the compressional structures. The overall structural setting was validated with a balanced cross-section. Out-of-sequence thrusting and non-coeval deformation within each thrust sheet characterize the local tectonic history.  相似文献   

A physical analogue model to analyse interactions between tensile stresses and dissolution in carbonate slopes     

Stefano Casini  Salvatore Martino  Marco Petitta  Alberto Prestininzi 《Hydrogeology Journal》2006,14(8):1387-1402

A physical analogue model was developed to analyse the relationship between tensional states in rock masses, seepage and karst processes. Use was made of an experimental apparatus consisting of two hydraulic circuits realized by drilling two holes into each of two blocks of sampled limestone from the central Apennines (Italy). A static load (208.85 kg) was applied to one of the blocks in order to elicit tensile stresses within it. Physical and chemical monitoring data showed that the main process involved was temperature-dependent CaCO₃ dissolution. This process was more marked in the loaded block circuit, as Ca⁺⁺ concentration in circulated water reached 54 mg/L, whereas only 28 mg/L was reached in the unloaded one. The interaction between load and dissolution caused the observed opening of microcracks, as confirmed by further increase of water loss and by dilution in the loaded block circuit, resulting in a decrease of Ca⁺⁺ concentration. These findings were confirmed by recording additional water losses after increasing the load up to 445.05 kg. A finite difference numerical model showed that tensile stresses (max 20 kPa) within the loaded block were clustered at the intersection of the main joints with the flowpaths, thus representing points of preferential and accelerated dissolution.This study is part of a research project on analogical and numerical modelling for geological risk mitigation being conducted at CERI, Research Centre for Geological Risks of the University of Rome “La Sapienza” (Valmontone, Roma, Italy; http://www.ceri@uniroma1.it).  相似文献   

Automatic seismic phase picking and consistent observation error assessment: application to the Italian seismicity     

R. Di Stefano  F. Aldersons  E. Kissling  P. Baccheschi  C. Chiarabba  D. Giardini 《Geophysical Journal International》2006,165(1):121-134

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Lava flow in tubes with elliptical cross sections     

Michele Dragoni  Stefano Santini   《Journal of Volcanology and Geothermal Research》2007,160(3-4):239-248

We develop a model of lava flow in a cylindrical tube with elliptical cross section. The lava is considered an isothermal, incompressible Newtonian fluid. We solve analytically the steady-state Navier–Stokes equation under a constant driving force, given by the component of gravity along the axis of the tube and obtain the velocity and stress field components in the fluid. The ratio between the flow rate of the elliptical tube and that of a circular tube, having the same cross sectional area, is found to be always less than 1 and to depend only on the value of eccentricity. The ratio decreases rapidly when the eccentricity becomes lower than about 0.5. The average flow velocity in a partially filled tube is calculated under the assumption of constant flow rate. In an elliptical tube, the shear traction is not uniform on the wall of the tube, but changes periodically with the position. It is maximum at the intersections with the minor axis and minimum at the intersections with the major axis, the ratio between the maximum and the minimum value being equal to the ratio between the lengths of the two axes. Assuming that the erosion rate of the wall of the tube is proportional to shear traction, we calculate the erosion of the wall as a function of time and find that its effect is such as to make the tube cross section closer to the circular shape.  相似文献   

Multi-stage thrusting at the "Penninic Front" in the Western Alps between Mont Blanc and Pelvoux massifs     

Stefano Ceriani  Bernhard Fügenschuh  Stefan M. Schmid 《International Journal of Earth Sciences》2001,90(3):685-702

The different segments of the tectonic boundary between external (European) and internal (Penninic) units in the Western Alps, the so-called Penninic Front (PF), formed at different times and according to different kinematic scenarios. During a first episode (Eocene), the PF corresponds to a transpressive suture zone between Penninic and European units. North- to NNW-trending stretching lineations, found along internal nappe contacts within the Penninic units, are related to this episode. This subduction zone was sealed by the Priabonian flysch of the Aiguilles d'Arves, a detrital trench formation that formed during the final stages of subduction. During a second episode, starting in mid-Oligocene times, the PF, imaged along the ECORS-CROP profile, acted as a WNW-directed thrust. This thrust, the Roselend Thrust (RT), only partially coincides with the PF. South of Moûtiers, the RT propagates into the Dauphinois units, carrying the former Eocene PF (including the Priabonian flysch) passively in its hangingwall. South of the Pelvoux massif the RT finds its continuation along the "Briançonnais Front", an out-of-sequence thrust behind the Embrunais-Ubaye nappes. On a larger scale, our findings indicate oblique (sinistral) collision within the future Western Alps during the Eocene, followed by westward indentation of the Adriatic block.  相似文献   

In Situ Multi-Element Analysis of the Mount Pinatubo Quartz-Hosted Melt Inclusions by NIR Femtosecond Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry     

Anastassia Yu. Borisova  Rémi Freydier  Mireille Polvé  Stefano Salvi  Frederic Candaudap  Thierry Aigouy 《Geostandards and Geoanalytical Research》2008,32(2):209-229

Microscopic melt inclusions found in magmatic minerals are undoubtedly one of the most important sources of information on the chemical composition of melts. This paper reports on the successful application of near-infrared (NIR) femtosecond laser ablation (LA) - inductively coupled plasma-mass spectrometry to in situ determination of incompatible trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Ta, Th, U) and ore metals (As, Mo, Pb) in individual melt inclusions hosted in quartz from the Mount Pinatubo dacites, Philippines. The determined elements cover a concentration range of five orders of magnitude. Femtosecond LA-ICP-MS analyses of twenty-eight individual melt inclusions demonstrate the efficiency of the microanalytical technique and suggests a spectacular homogeneity of the entrapped melt, at least with respect to the following incompatible trace elements: Rb, Sr, Nb, Cs, Ba, La, Ce, Pr, Nd, Pb, Th. The analytical precision (1s) for Na, Ca, Rb, Sr, Y, Nb, Ba and LREE ranged from 3 to 20%. Comparison of trace element concentrations in Mt. Pinatubo melt inclusions determined by femtosecond LA-ICP-MS with those of melt inclusions previously analysed by secondary ion mass spectrometry analysis (SIMS) and those of matrix glasses previously determined by nanosecond LA-ICP-MS showed an agreement typically within 30–40%. The homogeneity of trace element concentrations of the Mt. Pinatubo melt inclusions and the matrix glasses is consistent with the melt inclusion origin as homogeneous rhyolitic melt that was trapped in quartz phenocrysts at the final crystallisation stages of the host adakite (dacite) magma.  相似文献   

Polymorphism in sapphirine     

Stefano Merlino 《Contributions to Mineralogy and Petrology》1973,41(1):23-29

Sapphirine-1Tc, a polymorph of sapphirine, was found in granulites near Wilson Lake, Labrador. It is triclinic with unit cell data: a=10.04, b=10.38, c=8.65 Å, =107°33, =95°07, =123°55. The X-ray diffraction patterns of several crystals of sapphirine from Wilson Lake were investigated and evidence was found of solid state reactions that lead from the ordered polymorph-1Tc to a disordered arrangement of domains with the structure of sapphirine-2M, that is normal sapphirine.  相似文献   

Mutual Interference of Two Debris Flow Deposits Delivered in a Downstream River Reach   总被引：1，自引：0，他引：1  

STANCANELLI Laura Maria  LANZONI Stefano  FOTI Enrico 《山地科学学报》2014,(6):1385-1395

We investigate experimentally the depositions of two contiguous debris flows flowing into a main river reach.The aim of the present experimental research is to analyze the geometry and the mutual interactions of debris flow deposits conveyed by these tributaries in the main channel.A set of 19 experiments has been conducted considering three values of the confluence angle,two slopes of the tributary,and three different triggering conditions（debris flows occurring simultaneously in the tributaries,or occurring first either in the upstream or in the downstream tributary）.The flow rate along the main channel was always kept constant.During each experiment the two tributaries had the same slope and confluence angle.The analysis of the data collected during the experimental tests indicates that the volume of the debris fan is mainly controlled by the slope angle,as expected,while the shape of the debris deposit is strongly influenced by the confluence angle.Moreover,in the case of multiple debris flows,the deposit shape is sensitive to the triggering conditions.Critical index for damming formation available in literature has been considered and applied to the present case,and,on the basis of the collected data,considerations about possible extension of such indexes to the case of multiple confluences are finally proposed.  相似文献   

Improving Bayesian analysis for LISA Pathfinder using an efficient Markov Chain Monte Carlo method     

Luigi Ferraioli  Edward K. Porter  Michele Armano  Heather Audley  Giuseppe Congedo  Ingo Diepholz  Ferran Gibert  Martin Hewitson  Mauro Hueller  Nikolaos Karnesis  Natalia Korsakova  Miquel Nofrarias  Eric Plagnol  Stefano Vitale 《Experimental Astronomy》2014,37(1):109-125

We present a parameter estimation procedure based on a Bayesian framework by applying a Markov Chain Monte Carlo algorithm to the calibration of the dynamical parameters of the LISA Pathfinder satellite. The method is based on the Metropolis-Hastings algorithm and a two-stage annealing treatment in order to ensure an effective exploration of the parameter space at the beginning of the chain. We compare two versions of the algorithm with an application to a LISA Pathfinder data analysis problem. The two algorithms share the same heating strategy but with one moving in coordinate directions using proposals from a multivariate Gaussian distribution, while the other uses the natural logarithm of some parameters and proposes jumps in the eigen-space of the Fisher Information matrix. The algorithm proposing jumps in the eigen-space of the Fisher Information matrix demonstrates a higher acceptance rate and a slightly better convergence towards the equilibrium parameter distributions in the application to LISA Pathfinder data. For this experiment, we return parameter values that are all within ～1σ of the injected values. When we analyse the accuracy of our parameter estimation in terms of the effect they have on the force-per-unit of mass noise, we find that the induced errors are three orders of magnitude less than the expected experimental uncertainty in the power spectral density.  相似文献   

Synthetic observations using POLARIS: an application to simulations of massive prestellar cores     

Zamponi  Joaquin  Giannetti  Andrea  Bovino  Stefano  Sabatini  Giovanni  Schleicher  Dominik R. G.  K&#;rtgen  Bastian  Reissl  Stefan  Wolf  Sebastian 《Astrophysics and Space Science》2022,367(6):1-9

Astrophysics and Space Science - Dynamical evolution of galaxies is a complex process, especially the centers. Gravitationally coupled gas and stellar discs have been observed to coexist in the...  相似文献