Stochastic Modelling of Mineral Exploration Targets     

Talebi  Hassan  Mueller  Ute  Peeters  Luk J. M.  Otto  Alex  de Caritat  Patrice  Tolosana-Delgado  Raimon  van den Boogaart  K. Gerald 《Mathematical Geosciences》2022,54(3):593-621

Mathematical Geosciences - Mineral deposits are metal enrichment anomalies, occurring as local manifestations of the interplay between various geological processes that operate at a wide range of...  相似文献   

Variations in the response of the dune coast of northern France to major storms as a function of available beach sediment volume          下载免费PDF全文

Adrien Crapoulet  Arnaud Héquette  Denis Marin  Franck Levoy  Patrice Bretel 《地球表面变化过程与地形》2017,42(11):1603-1622

A series of airborne topographic LiDAR data were obtained from May 2008 to January 2014 over two coastal sites of northern France (Bay of Wissant and east of Dunkirk). These data were used with wind and tide gauge measurements to assess the impacts of storms on beaches and coastal dunes, and particularly of the series of major storms that hit western Europe during the fall and early winter of 2013. Our results show a high variability in shoreline response from one site to the other, but also within each coastal site. Coastal dune erosion and shoreline retreat occurred at both sites, particularly on the coast of the Bay of Wissant where shoreline retreat up to about 40 m was measured. However, stability or even shoreline advance were also observed despite the occurrence of an extreme water level with a return period >100 years during the storm Xaver in early December 2013. Comparison of shoreline change with variations of coastal dune and upper beach volumes revealed only weak relationships. Our results nevertheless showed that shoreline behavior seems to strongly depend on the initial sediment volume on the upper beach before the occurrence of the storms. According to our measurements, an upper beach volume of about 30 m³ m^?1 between the dune toe and the mean high water level is sufficient at these sites to protect the coastal dunes from storm waves associated with high water levels with return periods >10 years. The identification of such thresholds in terms of upper beach width or sediment volume may represent valuable information for improving the management of shoreline change by providing an estimate of the minimum quantity of sand on the upper beach necessary to ensure shoreline stability in this region. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Regionality and seasonality of submesoscale and mesoscale turbulence in the North Pacific Ocean   总被引：1，自引：0，他引：1  

Hideharu Sasaki  Patrice Klein  Yoshikazu Sasai  Bo Qiu 《Ocean Dynamics》2017,67(9):1195-1216

The kinetic energy (KE) seasonality has been revealed by satellite altimeters in many oceanic regions. Question about the mechanisms that trigger this seasonality is still challenging. We address this question through the comparison of two numerical simulations. The first one, with a 1/10° horizontal grid spacing, 54 vertical levels, represents dynamics of physical scales larger than 50 km. The second one, with a 1/30° grid spacing, 100 vertical levels, takes into account the dynamics of physical scales down to 16 km. Comparison clearly emphasizes in the whole North Pacific Ocean, not only a significant KE increase by a factor up to three, but also the emergence of seasonal variability when the scale range 16–50 km (called submesoscales in this study) is taken into account. But the mechanisms explaining these KE changes display strong regional contrasts. In high KE regions, such the Kuroshio Extension and the western and eastern subtropics, frontal mixed-layer instabilities appear to be the main mechanism for the emergence of submesoscales in winter. Subsequent inverse kinetic energy cascade leads to the KE seasonality of larger scales. In other regions, in particular in subarctic regions, results suggest that the KE seasonality is principally produced by larger-scale instabilities with typical scales of 100 km and not so much by smaller-scale mixed-layer instabilities. Using arguments from geostrophic turbulence, the submesoscale impact in these regions is assumed to strengthen mesoscale eddies that become more coherent and not quickly dissipated, leading to a KE increase.  相似文献   

Suspended sediment transport from the Gironde estuary (France) onto the adjacent continental shelf     

George P. Allen  Patrice Castaing 《Marine Geology》1973,14(5):47-53

Current velocity and suspended sediment concentration measurements at anchor stations in the downstream extremity of the Gironde estuary indicate that during periods of high river discharge, a significant amount of suspended sediment is transported out of the estuary onto the adjacent continental shelf. The vertical profile of the residual (non-tidal) suspended sediment flux is similar to that of the residual current velocity, with a net upstream flux near the bottom and an overlying seaward-directed transport. The overall, depth-integrated result is a net seaward transport of suspended sediment out of the estuary. It appears that this net seaward transport varies directly with tidal amplitude.Aerial photography and water sampling indicate that during high river inflow, the downstream extremity of the turbidity maximum extends onto the continental shelf at ebb tide. The tidal and coastal current patterns of the inlet and inner shelf induce a northward transport of the turbid estuarine water, and at each tidal cycle, a certain amount of suspended sediment leaves the estuary; part of this sediment is deposited in a silt and clay zone on the continental shelf.  相似文献   

Partitioning of organic matter in continental margin sediments among density fractions   总被引：5，自引：0，他引：5  

Stuart G. Wakeham  Elizabeth A. Canuel  Elizabeth J. Lerberg  Patrice Mason  Troy P. Sampere  Thomas S. Bianchi 《Marine Chemistry》2009,115(3-4):211-225

Hydrodynamic processes sort and redistribute organic matter (OM) and minerals on continental margins. Density fractionations were conducted on sediments from diverse margins (Mexico margin, Gulf of Mexico, Mississippi River delta, Eel River margin) to investigate the nature, provenance and age of OM among density fractions. Mass, elemental (C and N), lignin, and surface area distributions, as well as stable carbon and radiocarbon isotopic compositions were measured. The lowest density fractions (< 1.6 g cm^− 3) contained the highest organic carbon (OC) (up to 45%) and lignin concentrations (up to 8 mg g^− 1) due to abundant woody debris, whereas high density fractions (> 2.5 g cm^− 3) were OC-poor (%OC < 0.5) mineral material. Most sediment mass was found in the mesodensity fractions (1.6 to 2.5 g cm^− 3) that contained the highest proportion of OC (up to ~ 75%) for each sediment. Stable carbon isotope compositions (δ¹³C − 25.5‰ to − 22.9‰) show terrigenous OC as a significant component of density isolates from the river-dominated sediments (Gulf of Mexico, Mississippi River, and Eel margin), whereas the Mexico margin, least influenced by riverine input, was dominated by autochthonous marine OC (δ¹³C ~ − 21.5‰). Radiocarbon compositions of density fractions indicate significant pre-aged OC (Δ¹⁴C as low as − 900‰) in river-influenced sediments but not on the Mexico margin (Δ¹⁴C > − 200‰). Ratios of vanillic acid to vanillin (Ad/Al)v among lignin oxidation products increase with increasing particle density suggesting variable lignin sources or selective degradation of lignin among the different density fractions.  相似文献   

An urban neighborhood temperature and energy study from the CAPITOUL experiment with the Solene model     

Aurélien Hénon  Patrice G. Mestayer  Jean-Pierre Lagouarde  James A. Voogt 《Theoretical and Applied Climatology》2012,110(1-2):177-196

A methodology is proposed to analyze the radiative and thermal exchanges between a small urban neighborhood and the atmosphere based on the use of the thermoradiative model SOLENE and radiometric measurements to optimize the effective values of its constant parameters. Applied to the center of Toulouse, France, the optimization data are building surface temperatures measured with handheld radiometers and a downward-facing pyranometer during one of the intense observation periods of the CAnopy and Particles Interactions in TOulouse Urban Layer (CAPITOUL) experimental campaign. The quality of the simulations is assessed by comparing, without any other model adjustment, the model outputs for two diurnal cycles (1?day in summer and 1?day in winter) against two independent experimental datasets from fixed permanent radiometers and from sensors measuring the solar, infrared and sensible heat fluxes to the atmosphere at the top of a mast 30?m above the roofs. These simulations allow us to further analyze the separate contributions of the different surface classes, roofs, facades and pavement to these fluxes and to compare them with their counterparts observed over a neighborhood of Marseilles city center during a previous experiment. The partition is remarkably similar in Toulouse and Marseilles: 6–7% for the solar radiation, 73–76% for the infrared radiation and 17–20% for the sensible heat flux. The contribution of roofs to the infrared flux appears proportional to their plan area proportion (built density) but not the contributions to the other two fluxes. The contributions of facades to all three fluxes are roughly proportional to their fraction of the total surface area.  相似文献   

Hot orogens     

Dominique Chardon  Guest editor  Patrice Rey  Guest editor  Christian Teyssier  Guest editor  Donna L. Whitney  Guest editor 《Tectonophysics》2009,477(3-4):103

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K–Ar dating and δO–δD tracing of illitization within and outside the Shea Creek uranium prospect,Athabasca Basin,Canada     

Emmanuel Laverret  Norbert Clauer  Anthony Fallick  Julien Mercadier  Patricia Patrier  Daniel Beaufort  Patrice Bruneton 《Applied Geochemistry》2010

Isotope analyses (K–Ar, δ¹⁸O and δD) were performed on illite from both the sandstone cover and the underlying basement, close to and distant from Shea Creek, an unconformity-type U deposit (Athabasca Basin, Canada); the illite had previously been characterized crystallographically. In the barren areas away from deposit, illite is mainly of the cis-vacant 1M polytype occurring as relatively coarse-grained lath-shaped particles, while it occurs as fine-grained particles of the trans-vacant 1M type next to and in the U mineralized strata. The tectonic-induced hydrothermal system that favored illite crystallization was multi-episodic 1453 ± 2, 1330 ± 20 and probably about 1235 Ma ago. These illite-forming episodes appear to have occurred contemporaneously to those favoring the concentration of the associated U oxides, which were dated independently by the U–Pb method in the Shea Creek deposits and elsewhere in the Athabasca Basin.  相似文献   

Assessing climate change impacts,sea level rise and storm surge risk in port cities: a case study on Copenhagen   总被引：8，自引：1，他引：7  

Stéphane Hallegatte  Nicola Ranger  Olivier Mestre  Patrice Dumas  Jan Corfee-Morlot  Celine Herweijer  Robert Muir Wood 《Climatic change》2011,104(1):113-137

This study illustrates a methodology to assess the economic impacts of climate change at a city scale and benefits of adaptation, taking the case of sea level rise and storm surge risk in the city of Copenhagen, capital of Denmark. The approach is a simplified catastrophe risk assessment, to calculate the direct costs of storm surges under scenarios of sea level rise, coupled to an economic input–output (IO) model. The output is a risk assessment of the direct and indirect economic impacts of storm surge under climate change, including, for example, production and job losses and reconstruction duration, and the benefits of investment in upgraded sea defences. The simplified catastrophe risk assessment entails a statistical analysis of storm surge characteristics, geographical-information analysis of population and asset exposure combined with aggregated vulnerability information. For the city of Copenhagen, it is found that in absence of adaptation, sea level rise would significantly increase flood risks. Results call for the introduction of adaptation in long-term urban planning, as one part of a comprehensive strategy to manage the implications of climate change in the city. Mitigation policies can also aid adaptation by limiting the pace of future sea level rise.  相似文献   

Late Glacial and Holocene avulsions of the Rio Pastaza Megafan (Ecuador–Peru): frequency and controlling factors     

Carolina Bernal  Frédéric Christophoul  José Darrozes  Jean-Claude Soula  Patrice Baby  José Burgos 《International Journal of Earth Sciences》2011,100(7):1759-1782

The geomorphological study by means of remote sensing imagery of the Rio Pastaza Megafan (Ecuador and northern Peru) reveals the traces of numerous avulsions. One hundred and eight avulsion sites have been defined. The location of these sites, the available radiocarbon ages as well as historical maps of the seventeenth century, enable us to propose an evolution history of the migration and avulsions of the Rio Pastaza since the Last Glacial Maximum. The first avulsions of the Río Pastaza occurred after the LGM in a zone close to and roughly parallel to the sudandean front, where the developed avulsion gave a distributive pattern to the ancient stream of the Río Pastaza in an area located between the modern Río Morona and Pastaza, where they caused the Rio Pastaza to develop a fan-like distributary pattern. This is interpreted as a response to thrust-related forelimb tilt, progressively shifting eastward the Rio Pastaza and the apex of the megafan. This sequence of events ended with the Great Diversion of the Rio Pastaza towards the modern Rios Corrientes and Tigre. Avulsions occurred in the Tigre-Corrientes Area between 9200 and 8,500 years Cal BP. Afterwards, the Río Pastaza was diverted to its present-day north–south course. This last significant avulsion occurred before AD 1691. In the area located between the modern Río Morona and Pastaza, avulsion frequency—probably overestimated—ranges between 100 and 200 years. In the Ríos Tigre and Corrientes area, avulsion frequency—probably underestimated—ranges from 300 to 400 years. Regional tectonics is likely to have triggered most of the avulsions in the Morona Pastaza area but its influence is restricted to this area. The factors controlling the avulsions in the Tigre-Corrientes area are less clear because the frequently described “hydrologic”-driven avulsion as observed in areas characterized by contrasted hydrologic cycles are inconsistent with the characteristics of the hydrologic cycles of the Rio Pastaza.  相似文献