Brittle reactivation of mylonitic fabric and the origin of the Cenozoic Rio Santana Graben,southeastern Brazil     

Ambrosina Gontijo-Pascutti  Francisco H.R. Bezerra  Emanuele La Terra  Julio C.H. Almeida 《Journal of South American Earth Sciences》2010,29(2):522-536

In the Ribeira belt, southeastern Brazil, the Precambrian mylonitic fabric mainly formed during the Brasiliano/Pan-African orogeny (640–480 Ma) and was reactivated as fault zones in the Cretaceous and Cenozoic. The reactivation process led to the development of the System of Continental Rifts of southeastern Brazil, from the Paleogene to the Quaternary. We investigated the brittle reactivation of a mylonitic zone, which is part of a major mylonitic belt, Arcádia-Areal. We used geological and geomorphological mapping, resistivity survey, controlled source audiomagnetotelluric survey, and luminescence dating. Our results indicate that this shear zone was reactivated and formed a 15 km long and 2 km wide sedimentary-filled trough, the Rio Santana Graben. It is located on the northwest border of a major structure, the Guanabara Graben, in the State of Rio de Janeiro. The Rio Santana Graben forms an almost entirely fault-bounded, NE-elongated depression that was accommodated entirely within the Arcádia-Areal shear zone. The graben consists of two main depocenters separated by a relay ramp. The graben formed by means of multistage activity of several faults during at least two main periods. The first period formed silicified fault breccia and occurred during alkaline magmatism in the Paleogene. The second formed fault breccia and gouge in shallow conditions and occurred at least until the Quaternary. The NE-trending and NW-dipping Precambrian fabric was reactivated as dip-slip and strike-slip faults. These faults triggered clastic-sediment deposition at least 300 m thick. The upper part of the graben consists of Quaternary alluvial and colluvial sediment fill, which yielded maximum luminescence deposition ages from 49 to 13 ka in the center of the trough. An organic layer at the top of the Quaternary alluvial deposits yielded ¹⁴C ages at ～6000 years BP. The lower part of the graben may be composed of Paleogene to Neogene sedimentary deposits, which occur in other basins of the System of Continental Rifts of southeastern Brazil. We conclude that the Rio Santana Graben is an example of the direct control of a preexisting continental-scale rheological boundary on the geometry and location of fault systems and sediment deposition. Quaternary fault reactivation of the preexisting fabrics represents only the latest movement of a major structure.  相似文献   

The EChO payload instrument – an overview     

Paul Eccleston  Bruce Swinyard  Marcel Tessenyi  Giovanna Tinetti  Ingo Waldmann  Marc Ferlet  Ranah Irshad  Tanya Lim  Kevin Middleton  Tom Bradshaw  Martin Crook  Tom Hunt  Berend Winter  Ian Bryson  Naidu Bezawada  William Taylor  Neil Bowles  Enzo Pascale  Gianluca Morgante  Emanuele Pace  Alberto Adriani  Jean-Michel Reess  Marc Ollivier  Roland Ottensamer  Mirek Rataj  Gonzalo Ramos Zapata  Jan-Rutger Schrader  Avri Selig  Kate Isaak  Martin Linder  Ludovic Puig 《Experimental Astronomy》2015,40(2-3):427-447

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Galaxy Evolution from Deep Multicolor Surveys     

Emanuele Giallongo  Adriano Fontana 《Astrophysics and Space Science》2004,294(1-2):9-14

A composite sample of NIR-selected galaxies having extended multicolor coverage has been used to probe the cosmological evolution of the blue luminosity function and of the stellar mass function. The bright fraction of the sample has spectroscopic redshifts, and the remaining fraction well-calibrated photometric redshifts. The resulting blue luminosity function shows an increasing brightening with redshift respect to the local luminosity function. Hierarchical CDM models predictions are in agreement only at low and intermediate redshifts but fail to reproduce the observed brightening at high redshifts (z ∼ 2–3). This brightening marks the epoch where starburst activity triggered by galaxy interactions could be an important physical mechanism for the galaxy evolution. At the same time the NIR galaxy sample has been used to trace the evolution of the cosmological stellar mass density up to ∼3. A clear decrease of the average mass density is apparent with a fraction ∼15% of the local value at z ∼ 3. UV bright star-forming galaxies are substancial contributors to the evolution of the stellar mass density. Although these results are globally consistent with Λ–CDM scenarios, they tend to underestimate the mass density produced by more massive galaxies present at z > 2.  相似文献   

The Sustainable Pumping Rate Concept: Lessons from a Case Study in Central Italy     

Emanuele Romano  Elisabetta Preziosi 《Ground water》2010,48(2):217-226

The term sustainable pumping rate (SPR) is defined as the maximum pumping rate that can be maintained indefinitely without mining an aquifer, and is different from the concept of safe yield (SY), which takes into account also aspects related to the much wider concept of sustainability. The assessment of the SPR for the case study of Petrignano d'Assisi, an alluvial aquifer located in Central Italy, shows the need for a reliable estimate of the global water budget of the aquifer, particularly of the recharge under undisturbed conditions; however, the latter is not sufficient, because the SPR is affected also by the geometry of the aquifer, the hydraulic conductivity pattern, the variation of recharge/discharge ratio induced by the abstractions, and so on. All these aspects are analyzed by means of a numerical flow model calibrated both under undisturbed conditions (1974) and under exploitation conditions (1998 to 2004). The steady-state modeling results show that the relation between recharge and abstractions both at local and global scale is a key point in order to estimate a long-term SPR. Moreover, as it could be necessary to overexploit the aquifer for short periods, e.g., during drought episodes, the estimate of SPR must be performed also in transient conditions, in order to take into account the characteristic time of depletion and the successive recovery.  相似文献   

The radiation environment in L-2 orbit: implications on the non-X-ray background of the eROSITA pn-CCD cameras     

Emanuele Perinati  Chris Tenzer  Andrea Santangelo  Konrad Dennerl  Michael Freyberg  Peter Predehl 《Experimental Astronomy》2012,33(1):39-53

The pn-CCD cameras at the focal plane of the eROSITA space observatory will be the first X-ray (0.2?C12?keV) detector to operate in a L-2 orbit. Therefore, no direct information of instrumental non X-ray background (NXB) is available to make predictions for eROSITA. Since, in general, the instrumental NXB experienced in orbit has a major impact on the overall sensitivity of the cameras, we investigated and modeled the L-2 radiation environment and its interaction with the eROSITA mass distribution and cameras, in order to quantify the expected pn-CCD NXB level. We obtain an average value of NXB ??25% lower than that observed by the pn-CCDs on-board the XMM-Newton satellite, which is placed in a Highly Elliptical Orbit (HEO). We discuss this result in light of the differences between the L-2 and HEO space environments.  相似文献   

Rates, progenitors and cosmic mix of Type Ia supernovae     

Laura Greggio  Alvio Renzini  Emanuele Daddi 《Monthly notices of the Royal Astronomical Society》2008,388(2):829-837

Following an episode of star formation, Type Ia supernova events occur over an extended period of time, following a distribution of delay times (DDT). We critically discuss some empirically based DDT functions that have been proposed in recent years, some favouring very early (prompt) events, other very late (tardy) ones, and therefore being mutually exclusive. We point out that in both the cases the derived DDT functions are affected by dubious assumptions, and therefore there is currently no ground for claiming either a DDT strongly peaked at early times, or at late ones. Theoretical DDT functions are known to accommodate both prompt as well as late SN Ia events, and can account for all available observational constraints. Recent observational evidence exist that both single and double degenerate precursors may be able of producing SN Ia events. We then explore on the basis of plausible theoretical models the possible variation with cosmic time of the mix between the events produced by the two different channels, which, in principle, could lead to systematic effects on the SN Ia properties with redshift.  相似文献   

Beyond Copenhagen: a realistic climate policy in a fragmented world     

Carlo Carraro  Emanuele Massetti 《Climatic change》2012,110(3-4):523-542

In this paper we argue that the financial provisions of the Copenhagen Accord, if used primarily to mitigate greenhouse gas (GHGs) emissions, could compensate the lack of more energetic action on the domestic mitigation side. In order to maximize the mitigation potential, the Copenhagen Green Climate Fund (CGCF) should be transformed into the International Bank for Emissions Allowance Acquisition (IBEAA) envisaged by Bradford (2008). We estimate that 50 percent of the CGCF in 2020 (50 US billions) could finance from 2.1 to 3.3?Gt CO2-eq emission reductions, depending on the domestic mitigation effort of Annex I and Non-Annex I countries. We construct a matrix that shows the level of GHGs emissions in 2020 under all possible combinations of abatement pledges and international mitigation financing, thus highlighting a rich set of options to reach the same level of GHGs emissions in 2020.  相似文献   

Design,test and analysis of a light‐weight dissipative bracing system for seismic protection of structures     

Emanuele Renzi  Salvatore Perno  Silvia Pantanella  Vincenzo Ciampi 《地震工程与结构动力学》2007,36(4):519-539

The paper deals with the proposal and the experimental validation of a novel dissipative bracing system for the seismic protection of structures; compared with other similar systems, it is characterized by smaller size and weight, which makes it easier to move and to install, as well as particularly suitable to be inserted in light‐framed structures (e.g. steel structures of industrial plants). The proposed system consists of an articulated quadrilateral with steel dissipaters inserted, to be connected by tendons to frame joints; the prototypes have been designed and realized for the seismic protection of a two‐storey, large‐scale, steel frame, specially designed for shaking‐table tests. The paper, after an illustration of the system, and of its design and behaviour, presents the shaking‐table tests carried out. The experimental results have fully validated the proposed system, showing its good performance in controlling the seismic response of framed structures. A numerical non‐linear model, set up and validated on the basis of the physical tests, has been used to help interpreting the experimental results, but also to perform parametrical studies for investigating the influence of the design parameters on the performance of the control system. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Isotope stratigraphy of Neoproterozoic cap carbonates in the Araras Group, Brazil     

Carlos J.S. de Alvarenga  Marcel A. Dardenne  Roberto V. Santos  Emanuele R. Brod  Simone M.C.L. Gioia  Alcides N. Sial  Elton L. Dantas  Valderez P. Ferreira 《Gondwana Research》2008,13(4):469-479

The Neoproterozoic carbonate sequence on the southeastern border of the Amazon Craton is divided into three lithostratigraphic units: a basal cap dolomite, an intermediate limestone, limestone-mudstone unit, and an upper dolarenite-dolorudite unit. Sections of the cap-carbonate were measured from the inner shelf to the outer shelf. Carbon isotope ratios (relative to PDB) vary between − 10.5 and − 1.7‰ in cap dolomite, and between − 5.4 and + 0.1‰ in laminated limestone and mud-limestone. Limestones and mud-limestones exhibit ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.70740 to 0.70780. A comparative isotope stratigraphy between the inner-shelf and the middle-shelf basin shows differences in carbon isotope ratios: The cap dolomite and limestones have lower δ¹³C ratios on the border of the basin (inner shelf) than in the middle shelf of the basin. These lower values can be related to shallower environmental conditions and to a stronger influence of the continental border. The ⁸⁷Sr/⁸⁶Sr ratios are the same in both areas, and are consistent with seawater composition at around 600 Ma.  相似文献   

Weak and strong constraint data assimilation in the inverse Regional Ocean Modeling System (ROMS): Development and application for a baroclinic coastal upwelling system   总被引：4，自引：2，他引：4  

Emanuele Di Lorenzo  Andrew M. Moore  Hernan G. Arango  Bruce D. Cornuelle  Arthur J. Miller  Brian Powell  Boon S. Chua  Andrew F. Bennett 《Ocean Modelling》2007,16(3-4):160-187

We describe the development and preliminary application of the inverse Regional Ocean Modeling System (ROMS), a four dimensional variational (4DVAR) data assimilation system for high-resolution basin-wide and coastal oceanic flows. Inverse ROMS makes use of the recently developed perturbation tangent linear (TL), representer tangent linear (RP) and adjoint (AD) models to implement an indirect representer-based generalized inverse modeling system. This modeling framework is modular. The TL, RP and AD models are used as stand-alone sub-models within the Inverse Ocean Modeling (IOM) system described in [Chua, B.S., Bennett, A.F., 2001. An inverse ocean modeling system. Ocean Modell. 3, 137–165.]. The system allows the assimilation of a wide range of observation types and uses an iterative algorithm to solve nonlinear assimilation problems. The assimilation is performed either under the perfect model assumption (strong constraint) or by also allowing for errors in the model dynamics (weak constraints). For the weak constraint case the TL and RP models are modified to include additional forcing terms on the right hand side of the model equations. These terms are needed to account for errors in the model dynamics.Inverse ROMS is tested in a realistic 3D baroclinic upwelling system with complex bottom topography, characterized by strong mesoscale eddy variability. We assimilate synthetic data for upper ocean (0–450 m) temperatures and currents over a period of 10 days using both a high resolution and a spatially and temporally aliased sampling array. During the assimilation period the flow field undergoes substantial changes from the initial state. This allows the inverse solution to extract the dynamically active information from the synthetic observations and improve the trajectory of the model state beyond the assimilation window. Both the strong and weak constraint assimilation experiments show forecast skill greater than persistence and climatology during the 10–20 days after the last observation is assimilated.Further investigation in the functional form of the model error covariance and in the use of the representer tangent linear model may lead to improvement in the forecast skill.  相似文献