The tectono‐sedimentary evolution of a supra‐detachment rift basin at a deep‐water magma‐poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland     

Emmanuel Masini  Gianreto Manatschal  Geoffroy Mohn  Jean‐François Ghienne  François Lafont 《Basin Research》2011,23(6):652-677

We describe the tectono‐sedimentary evolution of a Middle Jurassic, rift‐related supra‐detachment basin of the ancient Alpine Tethys margin exposed in the Central Alps (SE Switzerland). Based on pre‐Alpine restoration, we demonstrate that the rift basin developed over a detachment system that is traced over more than 40 km from thinned continental crust to exhumed mantle. The detachment faults are overlain by extensional allochthons consisting of upper crustal rocks and pre‐rift sediments up to several kilometres long and several hundreds of metres thick, compartmentalizing the distal margin into sub‐basins. We mapped and restored one of these sub‐basins, the Samedan Basin. It consists of a V‐shape geometry in map view, which is confined by extensional allochthons and floored by a detachment fault. It can be restored over a minimum distance of 11 km along and about 4 km perpendicular to the basin axis. Its sedimentary infill can be subdivided into basal (initial), intermediate (widening) and top (post‐tectonic) facies tracts. These tracts document (1) formation of the basin initially bounded by high‐angle faults and developing into low‐angle detachment faults, (2) widening of the basin and (3) migration of deformation further outboard. The basal facies tract is made of locally derived, poorly sorted gravity flow deposits that show a progressive change from hangingwall to footwall‐derived lithologies. Upsection the sediments develop into turbidity current deposits that show retrogradation (intermediate facies tract) and starvation of the sedimentary system (post‐tectonic facies tract). On the scale of the distal margin, the syn‐tectonic record documents a thinning‐ and fining‐upward sequence related to the back stepping of the tectonically derived sediment source, progressive starvation of the sedimentary system and migration of deformation resulting in exhumation and progressive delamination of the thinned crust during final rifting. This study provides valuable insights into the tectono‐sedimentary evolution and stratigraphic architecture of a supra‐detachment basin formed over hyper‐extended crust.  相似文献   

Numerical simulation of bolt‐supported tunnels by means of a multiphase model conceived as an improved homogenization procedure     

Patrick de Buhan  Emmanuel Bourgeois  Ghazi Hassen 《国际地质力学数值与分析法杂志》2008,32(13):1597-1615

This paper examines the possibility of applying a homogenization procedure to analyze the convergence of a tunnel reinforced by bolts, regarded as periodically distributed linear inclusions. Owing to the fact that a classical homogenization method fails to account for the interactions prevailing between the bolts and the surrounding ground and thus tends to significantly overestimate the reinforcement effect in terms of convergence reduction, a so‐called multiphase model is presented and developed, aimed at improving the classical homogenization method. Indeed, according to this model, the bolt‐reinforced ground is represented at the macroscopic scale as the superposition of two mutually interacting continuous phases, describing the ground and the reinforcement network, respectively. It is shown that such a multiphase approach can be interpreted as an extension of the homogenization procedure, thus making it possible to capture the ground–reinforcement interaction in a proper way, provided the constitutive parameters of the model and notably those relating to the interaction law can be identified from the reinforced ground characteristics. The numerical implementation of this model in a finite element method‐based computer code is then carried out, and a first illustrative application is finally presented. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Deriving Star Formation Histories: Evolutionary or Population Synthesis Codes versus Color-Magnitude Diagrams     

Danielle Alloin  Carme Gallart  Emmanuel Fleurence  Emanuela Pompei  Daniel Raimann  Uta Fritze- Von Alvensleben  Sukyoung Yi 《Astrophysics and Space Science》2002,281(1-2):109-113

The goal of this project is to analyze the integrated-light spectrum of a region in the LMC bar, for which HST images are already available yielding color-magnitude diagrams reaching the oldest main-sequence turnoff. Then, we can derive the star formation history in this field through evolutionary/population synthesis of the integrated light from 330 to 990 nm by a variety of independent methods and compare the results with the - in principle - more reliable results derived from the analysis of the color-magnitude diagram (CMD). This confrontation is the key ‘truth-test’ needed for the understanding of the abilities and the limitations of the evolutionary/population synthesis methods that must be applied of necessity to unresolved nearby and far-away galaxies. We report here on the observational part of the project. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

A direct boundary element method for plane strain poroelasticity     

Alexander H.-D. Cheng  Emmanuel Detournay 《国际地质力学数值与分析法杂志》1988,12(5):551-572

This paper presents a direct boundary element method (BEM), formulated in the Laplace transform space, for plane strain poroelasticity. The paper expands on work by Cheng and Liggett by recasting the theoretical foundation of BEM within the framework of Rice and Cleary's formulation of the Biot theory of poroelasticity. Furthermore, the numerical algorithm is generalized to deal with both interior and exterior domain problems, and a method for indirectly calculating the Cauchy principal value of the singular integrals is presented. Formulae for the stress and flux inside the domain are also derived. Finally, the algorithm is validated by comparing the numerical results with the analytical solution of a borehole subject to a far-field deviatoric stress (exterior domain) and with the solution of Mandel's problem (interior domain). These two examples provide a critical test of the algorithm.  相似文献   

Northwest Africa 5958: A weakly altered CM‐related ungrouped chondrite,not a CI3          下载免费PDF全文

Emmanuel Jacquet  Jean‐Alix Barrat  Pierre Beck  Florent Caste  Jérôme Gattacceca  Corinne Sonzogni  Matthieu Gounelle 《Meteoritics & planetary science》2016,51(5):851-869

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Cretaceous–Cenozoic tectonic history of the Jiaojia Fault and gold mineralization in the Jiaodong Peninsula,China: constraints from zircon U–Pb,illite K–Ar,and apatite fission track thermochronometry     

Jun Deng  Changming Wang  Leon Bagas  Emmanuel John M. Carranza  Yongjun Lu 《Mineralium Deposita》2015,50(8):987-1006

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Impact of textural patterns on modeled rock weathering rates and size distribution of weathered grains     

Yoni Israeli  Eyal Salhov  Simon Emmanuel 《地球表面变化过程与地形》2021,46(6):1177-1187

Rock texture has a critical influence on the way rocks weather. The most important textural factors affecting weathering are grain size and the presence of cracks and stylolites. These discontinuities operate as planes of mechanical weakness at which chemical weathering is enhanced. However, it is unclear how different rock textures impact weathering rates and the size of weathered grains. Here, we use a numerical model to simulate weathering of rocks possessing grain boundaries, cracks, and stylolites. We ran simulations with either synthetic or natural patterns of discontinuities. We found that for all patterns, weathering rates increase with discontinuity density. When the density was <~25%, the weathering rate of synthetic patterns followed the order: grid > honeycomb > Voronoi > brick wall. For higher values, all weathering rates were similar. We also found that weathering rates decreased as the tortuosity of the pattern increased. Moreover, we show that textural patterns strongly impact the size distributions of detached grains. Rocks with an initial monomodal grain size distribution produce weathered fragments that are normally distributed. In contrast, rocks with an initial log-normal size distribution produce weathered grains that are log-normally distributed. For the natural patterns, weathering produced lower modality distributions.  相似文献   

The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq–Mauléon rift system (Western Pyrenees,SW France)     

Emmanuel Masini  Gianreto Manatschal  Julie Tugend  Geoffroy Mohn  Jean-Marie Flament 《International Journal of Earth Sciences》2014,103(6):1569-1596

In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauléon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal necking zone controlled by the north-vergent Southern Mauléon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauléon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauléon Detachment system is recorded by the coeval deposition of “sag” deposits above the necking zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauléon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauléon Detachment system. Reconciling observations from the Mauléon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauléon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).  相似文献   

Uncertainty Analysis of Geochemical Anomaly by Combining Sequential Indicator Co-simulation and Local Singularity Analysis     

Liu  Yue  Carranza  Emmanuel John M. 《Natural Resources Research》2022,31(4):1889-1908

Natural Resources Research - Accurate characterization of geochemical anomaly related to metal mineralization and quantification of uncertainty propagation in space prediction are important for...  相似文献   

Spatial and temporal analysis of observed trends in extreme precipitation events in different climatic zones of Nigeria     

Ogolo  Emmanuel O.  Matthew  Olaniran J. 《Theoretical and Applied Climatology》2022,148(3-4):1335-1351

Theoretical and Applied Climatology - The purpose of this study is to assess spatial and temporal changes in extreme precipitation events from 1983 to 2017 over different climatic regions of...  相似文献