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11.
Pierre Horgue Romain Guibert Hervé Gross Patrice Creux Gérald Debenest 《Computational Geosciences》2015,19(6):1159-1169
This work presents a new subdivision method to upscale absolute permeability fields. This process, called two-step method, consists in (i) solving micro-scale equations on subdomains obtained from the full domain regular decomposition and (ii) solve a second upscaling with Darcy’s law on the permeability fields obtained in the first step. The micro-scale equations used depend on the case studied. The two-step upscaling process is validated on randomly generated Darcy-scale permeability fields by measuring the numerical error induced by upscaling. The method is then applied to real domains obtained from sandstone micro-tomographic images. The method specificities due to pore-space structure are discussed. The main advantage of the two-step upscaling method resides in the drastic reduction of computational costs (CPU time and memory usage) while maintaining a numerical error similar to that of other upscaling procedures. This new upscaling method may improve permeability predictions by the use of finer meshes or larger sample volumes. 相似文献
12.
This heuristic study of the urban morphology influence on urban albedo is based on some 3,500 simulations with the Solene model. The studied configurations include square blocks in regular and staggered rows, rectangular blocks with different street widths, cross-shaped blocks, infinite street canyons and several actual districts in Marseilles, Toulouse and Nantes, France. The scanned variables are plan density, facade density, building height, layout orientation, latitude, date and time of the day. The sky-view factors of the ground and canopy surfaces are also considered. This study demonstrates the significance of the facade density, in addition to the built plan density, as the explanatory geometrical factor to characterize the urban morphology, rather than building height. On the basis of these albedo calculations the puzzling results of Kondo et al. (Boundary-Layer Meteorol 100:225–242, 2001) for the influence of building height are explained, and the plan density influence is quantitatively assessed. It is shown that the albedo relationship with plan and facade densities obtained with the regular square plot configuration may be considered as a reference for all other configurations, with the exception of the infinite street canyon that shows systematic differences for the lower plan densities. The curves representing this empirical relationship may be used as a sort of abacus for all other geometries while an approximate simple mathematical model is proposed, as well as relationships between the albedo and sky-view factors. 相似文献
13.
The definition and inventory of the upper units of the Antalya Nappes or “Calcareous Antalya Nappes” (CAN) are still a matter of controversies and often conflicting interpretations. In the Gedeller type locality, we logged a new succession that sheds light on the detailed stratigraphy of the Upper Antalya Nappes. The lower part of the series corresponds to the uppermost part of the Kemer Gorge Nappe and is overthrust by the Ordovician Seydişehir Formation of the Tahtalı Dağ Nappe. The newly described Gedeller Formation belongs to the Kemer Gorge Nappe and is represented by Campanian (Upper Cretaceous) Scaglia-type pelagic limestones, which yielded radiolarians of the Amphipyndax pseudoconulus Zone. It is demonstrated that the “Calcareous Antalya Nappes” are composed of three different nappes, the Kemer Gorge, Bakırlı and the Tahtalı Dağ nappes, all of them belonging to the Upper Antalya Nappes system. 相似文献
14.
Talebi Hassan Mueller Ute Tolosana-Delgado Raimon Grunsky Eric C. McKinley Jennifer M. Caritat Patrice de 《Natural Resources Research》2019,28(3):869-891
Prediction of true classes of surficial and deep earth materials using multivariate spatial data is a common challenge for geoscience modelers. Most geological processes leave a footprint that can be explored by geochemical data analysis. These footprints are normally complex statistical and spatial patterns buried deep in the high-dimensional compositional space. This paper proposes a spatial predictive model for classification of surficial and deep earth materials derived from the geochemical composition of surface regolith. The model is based on a combination of geostatistical simulation and machine learning approaches. A random forest predictive model is trained, and features are ranked based on their contribution to the predictive model. To generate potential and uncertainty maps, compositional data are simulated at unsampled locations via a chain of transformations (isometric log-ratio transformation followed by the flow anamorphosis) and geostatistical simulation. The simulated results are subsequently back-transformed to the original compositional space. The trained predictive model is used to estimate the probability of classes for simulated compositions. The proposed approach is illustrated through two case studies. In the first case study, the major crustal blocks of the Australian continent are predicted from the surface regolith geochemistry of the National Geochemical Survey of Australia project. The aim of the second case study is to discover the superficial deposits (peat) from the regional-scale soil geochemical data of the Tellus Project. The accuracy of the results in these two case studies confirms the usefulness of the proposed method for geological class prediction and geological process discovery.
相似文献15.
Wolf Uwe Reimold Alvaro Penteado Crsta Maximilian Hasch Astrid Kowitz Natalia Hauser Joana Paula Sanchez Luiz Sergio Amarante Simes Grace Juliana de Oliveira Patrice T. Zaag 《Meteoritics & planetary science》2019,54(10):2384-2397
Cerro do Jarau is a conspicuous, circular morpho‐structural feature in Rio Grande do Sul State (Brazil), with a central elevated core in the otherwise flat “Pampas” terrain typical for the border regions between Brazil and Uruguay. The structure has a diameter of approximately 13.5 km. It is centered at 30o12′S and 56o32′W and was formed on basaltic flows of the Cretaceous Serra Geral Formation, which is part of the Paraná‐Etendeka Large Igneous Province (LIP), and in sandstones of the Botucatu and Guará formations. The structure was first spotted on aerial photographs in the 1960s. Ever since, its origin has been debated, sometimes in terms of an endogenous (igneous) origin, sometimes as the result of an exogenous (meteorite impact) event. In recent years, a number of studies have been conducted in order to investigate its nature and origin. Although the results have indicated a possible impact origin, no conclusive evidence could be produced. The interpretation of an impact origin was mostly based on the morphological characteristics of the structure; geophysical data; as well as the occurrence of different breccia types; extensive deformation/silicification of the rocks within the structure, in particular the sandstones; and also on the widespread occurrence of low‐pressure deformation features, including some planar fractures (PFs). A detailed optical microscopic analysis of samples collected during a number of field campaigns since 2007 resulted in the disclosure of a large number of quartz grains from sandstone and monomict arenite breccia from the central part of the structure with PFs and feather features (FFs), as well as a number of quartz grains exhibiting planar deformation features (PDFs). While most of these latter grains only carry a single set of PDFs, we have observed several with two sets, and one grain with three sets of PDFs. Consequently, we here propose Cerro do Jarau as the seventh confirmed impact structure in Brazil. Cerro do Jarau, together with Vargeão Dome (Santa Catalina state) and Vista Alegre (Paraná State), is one of very few impact structures on Earth formed in basaltic rocks. 相似文献
16.
Cécile Gautheron Nicolas Espurt Jocelyn Barbarand Martin Roddaz Patrice Baby Stéphane Brusset Laurent Tassan‐Got Eric Douville 《Basin Research》2013,25(4):419-435
Although the structure of the central Peruvian Subandean zone is well defined, the timing of thrust‐related exhumation and Cenozoic sedimentation remain poorly constrained. In this study, we report new apatite (U–Th)/He (AHe) and fission track (AFT) ages from thrust‐belt and foreland strata along three published balanced cross sections. AHe data from the northern, thick‐skinned domain (i.e. Shira Mountain, Otishi Cordillera and Ucayali Basin) show young AHe ages (ranging from 2.6 ± 0.2 to 13.1 ± 0.8 Ma) compared with AFT ages (ranging from 101 ± 5 to 133 ± 11 Ma). In the southern Camisea Basin, where deformation is mainly thin‐skinned, AHe and AFT ages have been both reset and show young cooling ages (3.7 ± 0.8 Ma and 8 ± 2 Ma respectively). Using low‐temperature thermochronology data and the latest fission track annealing and He diffusion codes, the thermal history of the study area has been reconstructed using inverse modelling. This history includes two steps of erosion: Early Cretaceous and late Neogene, but only Neogene sedimentation and exhumation varies in the different sectors of the study area. From a methodological point of view, large AHe data dispersion point to the need for refinement of AHe damage and annealing models. The influence of grain chemistry on damage annealing, multiple age components and the possibility of fission tracks as traps for He need further consideration. For the central Peruvian Subandes, AHe and AFT ages combined with balanced cross sections emphasize the dominant control of Paleozoic inheritance rather than climate on Cenozoic infilling and exhumation histories. Finally, our data provide the first field example of how thick‐skinned thrust‐related deformation and exhumation in the Subandes can be directly dated through AHe thermochronology. 相似文献
17.
Pierre Boszczuk Li Zhen Cheng Hanafi Hammouche Patrice Roy Sylvain Lacroix Alain Cheilletz 《Journal of Applied Geophysics》2011,75(1):77-86
Two inversions, unconstrained and constrained, of a gravity survey of the Matagami mining camp (Abitibi Archaean Subprovince, Canada) have been performed in order to identify the downward extension of a rhyolitic horizon hosting VMS-type base metals deposit and the morphologies of the major felsic plutons. A comparative study exhibits the similarities between measured and calculated densities from chemical compositions of the Matagami lithologies. This allows building an initial 3D geodensity model which integrates densities and available structural and geological surface mapping data. This model is integrated during the iteration process of the constrained inversion in the objective function. The resulting true density model and two derived cross-sections upgrade the 3D imaging of this area. Also, the model gives new insight for regional geological interpretation exposing possible shapes of the main geological units at depth and suggests the potential existence of deep fertile geological bodies. 相似文献
18.
AbstractIn the Moldanubian domain of the Vosges massif (INK France) euperimposition of three distinct crustal units has been attributed to Middle to Late Carboniferous thrusting. Л kinematic analysis of mierostuetures within each unit suggests that extension, following the formation of a Stack of nappes, is actually responsible for the bulk structure of this region. In order to estimate the related exhumation, the temperature and pressure evolution of the lowermost unit is investigated. It is characterised by (i) a prograde evolution within the stability field of kyanite, followed by (ii) a syn-kinematic, 3-4 kbar, near-isothermal decompression before (iii) cooling. Thermal modeling shows that the isothermal decompression may be related to rapid exhumation (> I mm.a-1), which cannot be accounted for by erosion alone. Therefore, exhumation is best explained by extensional processes, possibly related to gravitational collapse of a thickened crust. 相似文献
19.
20.
Patrice Christmann 《Natural Resources Research》2018,27(2):159-177
Minerals and the metals derived therefrom are non-renewable resources that deliver a wide range of goods and services to mankind. While their value has been recognized since thousands of years, their large-scale industrial production only really took off after World War II, thanks to the availability of efficient industrial production processes and of a rapidly rising demand, driven by demographic growth, urbanization and growing economic affluence in developed countries. The fast development of the Chinese economy, with about 300 million people reaching middle-class status and migrating to cities, drove a boom demand for minerals and metals of unprecedented magnitude in terms of tonnages consumed, that lasted from 2002 to 2013. Over a century, from 1914 to 2013, the production and consumption of pig iron, manganese and copper grew by a factor of 20, that of chromium by a factor of 182 and that of phosphate by a factor of nearly 42, while humanity grew only by a factor of about 4. Driven by demographic growth, continuing urbanization and growth of the global middle class the demand for minerals and metals will continue to exponentially grow. A scenario is proposed assessing what the theoretical requirements could be up to 2050 for minerals and metals commonly used in the construction industry, to develop infrastructure, for the mass production of metal intensive goods such as cars or in agriculture, to provide our food. The scenario, built on the trends observed since 1950, foresees that, by 2050, the demand for aluminium demand could be eight times the current production levels and the production of cement would need to grow by a factor of 7 to meet the 2050 level of demand. The lead demand would double by 2050. While geological scarcity does not appear to be an issue to feed such a demand, many factors are likely to limit the amount of minerals and metals that can be sustainably produced. Energy and water, both essential to mining, ore processing and metallurgy are likely to be limiting factors, as well as the sustainable management of the enormous amount of waste that would be generated. Public acceptance and access to exploration and mine development financing are other limiting factors to be considered. Inter-generational equity among all the stakeholders is concerned by mining, and intra-generational equity is necessary to ensure that the use of non-renewable natural capital provides benefits that last well beyond the closure of mining operations. This requires equity among stakeholders, including with nature, the silent stakeholder our lives depend on. Overcoming the challenges of the twenty-first century will require the following factors: Failure to act on the above requirements at the global scale is likely to be a source of deep crisis where all humanity could lose.
相似文献
- Decoupling economic growth from its unsustainable negative environmental impacts (UNEP 2011a), inter alia to reduce the pressure on natural resources;
- Rapid development of a more circular economy based on resource efficiency and the systematic minimization of waste. Flanking policy measures (for instance: European Commission 2016) are needed to close the natural resources loop and avoid the dire predicaments of resources depletion;
- Institutional strengthening and capacity building to ensure that sustainability agendas are developed and well integrated in corporate strategies and public policies; and
- Trust among the stakeholders, based on corporate accountability, transparency, stakeholder engagement and reporting of the economic, environmental, governance and social performance of companies.