Re‐orientation of the extension direction and pure extensional faulting at oblique rift margins: comparison between the Main Ethiopian Rift and laboratory experiments     

Giacomo Corti  Melody Philippon  Federico Sani  Derek Keir  Tesfaye Kidane 《地学学报》2013,25(5):396-404

In this study, we draw on a unique combination of well‐resolved fault‐slip data and earthquake focal mechanisms to constrain spatial variations in style of faulting in the obliquely extending Main Ethiopian Rift, East Africa. These data show that both boundary and internal faults – oblique and orthogonal to the plate divergence (PD) respectively – exhibit almost pure dip‐slip motion, and indicate significant local deflection in orientation of the extension direction at rift margins. Scaled analogue models closely replicate the multidisciplinary observations from the rift and suggest that the process is controlled by the presence of a deep‐seated, pre‐existing weakness – oblique to the direction of PD – that is able to cause a local rotation in the orientation of the extension direction at rift margins. Minor counterclockwise block rotations are required to accommodate the difference in slip direction along the different fault systems, as supported by existing and new palaeomagnetic data from the rift.  相似文献   

Three dimensional elasto‐plastic interface for embedded beam elements with interaction surface for the analysis of lateral loading of piles          下载免费PDF全文

Diego F. Turello  Federico Pinto  Pablo J. Sánchez 《国际地质力学数值与分析法杂志》2017,41(6):859-879

This paper presents a numerical formulation for a three dimensional elasto‐plastic interface, which can be coupled with an embedded beam element in order to model its non‐linear interaction with the surrounding solid medium. The formulation is herein implemented for lateral loading of piles but is able to represent soil‐pile interaction phenomena in a general manner for different types of loading conditions or ground movements. The interface is formulated in order to capture localized material plasticity in the soil surrounding the pile within the range of small to moderate lateral displacements. The interface is formulated following two different approaches: (i) in terms of beam degrees of freedoms; and (ii) considering the displacement field of the solid domain. Each of these alternatives has its own advantages and shortcomings, which are discussed in this paper. The paper presents a comparison of the results obtained by means of the present formulation and by other well‐established analysis methods and test results published in the literature. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Geochemical evidence for sediment provenance in mudstones and fossil‐poor wackestones (Upper Jurassic,Majorca Island)     

Rute Coimbra  Federico Olóriz 《地学学报》2012,24(6):437-445

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A new method for laboratory estimation of the transverse dispersion coefficient     

Massabò M  Catania F  Paladino O 《Ground water》2007,45(3):339-347

We introduce a method for identifying the transverse dispersion coefficient in laboratory experiments based on the analytical solution of a pulse injection of a nonreactive solute in a soil column (cylindrical geometry) packed with a homogeneous porous medium. This method takes into account the effect of boundary conditions such as no flux on the column perimeter, and it does not need a priori knowledge of the longitudinal dispersion coefficient. Numerical applications of the method show that it is stable and robust and that the results are reasonably in accordance with those found using the classical maximum likelihood method.  相似文献   

The severe zonda wind event of 11 July 2006 east of the Andes Cordillera (Argentine): a case study using the BRAMS model     

Federico Augusto Norte  Ana Graciela Ulke  Silvia Carmen Simonelli  Maximiliano Viale 《Meteorology and Atmospheric Physics》2008,102(1-2):1-14

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Late Quaternary glaciation history of Isla de los Estados,southeasternmost South America     

Per Möller  Christian Hjort  Svante Björck  Jorge Rabassa  Juan Federico Ponce 《Quaternary Research》2010,73(3):521-534

Isla de los Estados is a mountainous island southeast of Tierra del Fuego, in southernmost South America. Its central and eastern parts have an alpine topography, transected by U-shaped valleys, small, partly over-deepened fjords, and a multitude of abandoned cirques, all associated with extensive former local glaciations. Traces of glacial erosion generally reach 400–450 m a.s.l., and above that trimline a distinct sharp-edged nunatak derived landscape is present. The westernmost part of the island has a lower, more subdued topography, reflecting its “softer” geology but possibly also over-running and erosion by mainland-derived ice streams. The present study concentrated on glacigenic sediment sequences exposed along coastal erosional cliffs. A combination of OSL and ¹⁴C datings show that these sediments mostly date from the latest (Wisconsinan/Weichselian) glacial cycle, i.e. from the last ca. 100 ka with the oldest (glaciolacustrine) deposits possibly as old as 90–80 ka. The upper parts of overlying tills, with associated lateral and terminal moraines from glaciers that expanded onto an eustatically exposed dry shelf north of the island, date from the last global glacial maximum (LGM). Radiocarbon ages of peat and lake sediments indicate that deglaciation began 17–16 cal ka BP.  相似文献   

Mathematical treatment of isotopologue and isotopomer speciation and fractionation in biochemical kinetics     

Federico Maggi  William J. Riley 《Geochimica et cosmochimica acta》2010,74(6):1823-1835

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Recent Trends Towards Oligotrophication of the Northern Adriatic: Evidence from Chlorophyll <Emphasis Type="Italic">a</Emphasis> Time Series     

Patricija Mozetič  Cosimo Solidoro  Gianpiero Cossarini  Giorgio Socal  Robert Precali  Janja Francé  Franco Bianchi  Cinzia De Vittor  Nenad Smodlaka  Serena Fonda Umani 《Estuaries and Coasts》2010,33(2):362-375

The results of the updated and quality-checked data base of field observations on chlorophyll a (Chl a) collected in the period 1970–2007 in the Northern Adriatic Sea are presented. From the last decade, SeaWiFS satellite information was also considered. Results demonstrate a global tendency towards Chl a reduction in the period of investigation, which is more marked in the eutrophic area under the influence of the Po River. In the rest of the basin, which presents meso- or oligotrophic characteristics, long-term changes are more difficult to detect. The long-term field dataset can be divided into two periods: the last decade characterized by the strong decrease observed in the whole northern Adriatic and the earlier period with no or slight increase. The recent substantial reduction of Chl a concentrations is confirmed all over the basin (−0.11 mg m⁻³ year⁻¹) from satellite-derived information. Results are consistent with recently evidenced decrease in concentrations of phosphate and ammonia and point to the existence of oligotrophication in the Northern Adriatic. Results indicate forcefully that the still common perception of the Adriatic Sea as a very eutrophic basin is no longer appropriate, at least for its northern part and in recent years.  相似文献   

Comparing predictive capability of statistical and deterministic methods for landslide susceptibility mapping: a case study in the northern Apennines (Reggio Emilia Province, Italy)   总被引：5，自引：3，他引：2  

Federico Cervi  Matteo Berti  Lisa Borgatti  Francesco Ronchetti  Federica Manenti  Alessandro Corsini 《Landslides》2010,7(4):433-444

Statistical and deterministic methods are widely used in geographic information system based landslide susceptibility mapping. This paper compares the predictive capability of three different models, namely the Weight of Evidence, the Fuzzy Logic and SHALSTAB, for producing shallow earth slide susceptibility maps, to be included as informative layers in land use planning at a local level. The test site is an area of about 450 km² in the northern Apennines of Italy where, in April 2004, rainfall combined with snowmelt triggered hundreds of shallow earth slides that damaged roads and other infrastructure. An inventory of the landslides triggered by the event was obtained from interpretation of aerial photos dating back to May 2004. The pre-existence of mapped landslides was then checked using earlier aerial photo coverage. All the predictive models were run on the same set of geo-environmental causal factors: soil type, soil thickness, land cover, possibility of deep drainage through the bedrock, slope angle, and upslope contributing area. Model performance was assessed using a threshold-independent approach (the ROC plot). Results show that global accuracy is as high as 0.77 for both statistical models, while it is only 0.56 for SHALSTAB. Besides the limited quality of input data over large areas, the relatively poorer performance of the deterministic model maybe also due to the simplified assumptions behind the hydrological component (steady-state slope parallel flow), which can be considered unsuitable for describing the hydrologic behavior of clay slopes, that are widespread in the study area.  相似文献   

An example of flow differentiation: clinopyroxenite of the Predazzo igneous complex (north Italy)     

Federico Lucchini  Lauro Morten 《Lithos》1977,10(1):39-47

Chemical, modal and mineralogic data and textural observations suggest that the small mafic-ultramafic body at Predazzo, consisting of olivine-bearing gabbro, clinopyroxenite and quartz-bearing gabbro, is the result of a flow differentiation mechanism acting on a mush formed of 60% solid plus 40% liquid. Such a mechanism was capable of producing the concentration of the early formed crystals ($\text{cpx}\text{+}\text{mt}$) towards the center of the body (clinopyroxenite) with segregation of two portions enriched in liquid toward the margins (olivine- and quartz-bearing gabbros).  相似文献