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101.
Visualizing geomorphology: improving communication of data and concepts through engagement with the arts
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102.
103.
Gilberto Charifo António M. Ferreira José A. Almeida Jean‐Pierre Prian 《Resource Geology》2014,64(1):58-75
The Eocene Farim‐Saliquinhé phosphate mineralization (FSPM) is a buried sedimentary deposit located in the northern part of Guinea‐Bissau, discovered and spatially constrained during the 1980s by the French Geological Survey (BRGM). In the present work some of the data collected at that time are reworked in the framework of the development of a 3D geological and geochemical model of this mineralization. We show the usefulness of two classical multivariate statistical methods – principal component analysis (PCA) and cluster analysis (CA) – applied to eight geochemical variables (P2O5, SiO2, Al2O3, Fe2O3, CaO, MgO, F and CO2) measured in 247 samples from phosphate facies, for differentiation of samples taken from the different phosphate facies recognized in the FSPM, namely the main ore FPA (30 to 35% high grade phosphate), the calcareous low grade phosphate FPB (10 to 20% P2O5) (both Lutetian), and a mineralized Upper Eocene to Lower Oligocene cover (mainly including the FPO level and a silico‐aluminous phosphate bed), overlying the FPA, which can also be considered a third set of phosphate facies associated with the FSPM. 相似文献
104.
Umberto Tomassetti António A. Correia Francesco Graziotti Andrea Penna 《地震工程与结构动力学》2019,48(11):1297-1318
Typical low-rise masonry buildings consist of unreinforced masonry (URM) walls covered with various timber roof configurations generally supported or finished by masonry gables. Post-earthquake observations and experimental outcomes highlighted the large vulnerability of the URM gables to the development of overturning mechanisms, both because of the inertial out-of-plane excitation and the in-plane timber diaphragm deformability. This paper presents the static and dynamic experimental seismic performance of three full-scale roofs tested via quasi-static cyclic and shake table tests. Two of them were tested as part of a whole full scale one-storey and two-storey building. A single-degree-of-freedom (SDOF) numerical model is calibrated against experimental data and proposed for the analysis of this roof typology's dynamic behaviour. Several sets of analyses were conducted to assess the vulnerability of these structural components and to study the effect of the whole building's characteristics (eg, number of storeys and structural stiffness and strength) on the seismic performance of this roof typology. 相似文献
105.
George R. Priest Chris Goldfinger Kelin Wang Robert C. Witter Yinglong Zhang António M. Baptista 《Natural Hazards》2010,54(1):27-73
To explore the local tsunami hazard from the Cascadia subduction zone we (1) evaluate geologically reasonable variability
of the earthquake rupture process, (2) specify 25 deterministic earthquake sources, and (3) use resulting vertical coseismic
deformations for simulation of tsunami inundation at Cannon Beach, Oregon. Maximum runup was 9–30 m (NAVD88) from earthquakes
with slip of ~8–38 m and M
w ~8.3–9.4. Minimum subduction zone slip consistent with three tsunami deposits was 14–15 m. By assigning variable weights
to the source scenarios using a logic tree, we derived percentile inundation lines that express the confidence level (percentage)
that a Cascadia tsunami will not exceed the line. Ninety-nine percent of Cascadia tsunami variation is covered by runup ≤30 m and 90% ≤16 m with a “preferred”
(highest weight) value of ~10 m. A hypothetical maximum-considered distant tsunami had runup of ~11 m, while the historical
maximum was ~6.5 m. 相似文献
106.
Can the pattern of juvenile recruitment and population structure of the speckled swimming crab Arenaeus cribrarius (Decapoda: Brachyura) be determined by geographical variations?
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Luciana Segura de Andrade Israel Fernandes Frameschi Antônio Leão Castilho Rogério Caetano da Costa Adilson Fransozo 《Marine Ecology》2015,36(4):950-958
This study evaluated the effect of environmental stimuli and selective pressures in different geographical areas along a latitudinal gradient, on the juvenile recruitment, population structure, and sex ratio of the speckled swimming crab Arenaeus cribrarius. Samples were collected monthly during 1 year in three locations along the Brazilian coast: Macaé, state of Rio de Janeiro (MAC, 22°47′ S, 41°45′ W); Ubatuba, São Paulo (UBA, 23°27′ S, 44°58′ W); and São Francisco do Sul, Santa Catarina (SFS, 26°08′ S, 48°34′ W). The specimens of A. cribrarius were identified, counted, sexed, and measured for maximum carapace width (CW). The largest juvenile found was in UBA (47.7 ± 1.36 mm); and the largest adult females and males in MAC (74.26 ± 0.93 and 77.04 ± 0.79 mm, respectively). Recruitment in MAC was continuous, whereas in UBA and SFS, recruitment showed seasonal characteristics. The sex ratio was skewed toward females only in UBA; in MAC and SFS, males and females were present in equal proportions. These results indicate that geographical variations can cause differences in the recruitment and population structure of A. cribrarius. These regional differences call attention to the necessity for improved management plans and control of shrimp fishing, which can affect population patterns such as juvenile recruitment, population structure and life history of the target species and species that are caught in bycatch from shrimping, such as the swimming crab A. cribrarius. 相似文献
107.
Astuto Giuseppe Molina-Gómez Fausto Bilotta Emilio Viana da Fonseca António Flora Alessandro 《Acta Geotechnica》2023,18(2):777-790
Acta Geotechnica - This work stems from the need to validate a technique for a reliably measurement of the degree of saturation (Sr) in deposits composed of sandy soils to improve their... 相似文献
108.
Antônia Tatiana Pinheiro do Nascimento Natália Holanda Maia Cavalcanti Bruno Parente Leitão de Castro 《水文科学杂志》2019,64(1):80-91
In the Brazilian semi-arid region, thousands of small dams have been built over time to enhance water availability, accumulating water and hydraulic energy at high altitudes. Simulations were performed in this study to assess how the arrangement of reservoirs impacts on the power demand for water distribution in the Banabuiú River Basin (19?800 km2), Brazil. The power required to pump water from 1405 reservoirs to all districts with diffuse demands is 6.5 GWh/year, whereas in the scenario with only the 12 larger strategic reservoirs, the power demand reached 45.3 GWh/year. Alone, the largest reservoir in the basin can supply water to all districts. Nonetheless, in that scenario, the power demand would reach 195 GWh/year, which is 30 times the power required in the real reservoir arrangement. Thus, decentralization by small reservoirs not only promotes more democratic access to water, but also increases energy efficiency by storing it at higher altitudes and closer to the diffuse demands. 相似文献
109.
Riegel Roberta Plangg Alves Darlan Daniel Schmidt Bruna Caroline de Oliveira Guilherme Garcia Haetinger Claus Osório Daniela Montanari Migliavacca Rodrigues Marco Antônio Siqueira de Quevedo Daniela Muller 《Natural Hazards》2020,103(1):497-511
Natural Hazards - The increase in the frequency of natural disasters in recent years and its consequent social, economic and environmental impacts make it possible to prioritize areas of risk as an... 相似文献
110.
Gerben Van Ranst Antônio Carlos Pedrosa-Soares Tiago Novo Pieter Vermeesch Johan De Grave 《地学前缘(英文版)》2020,11(1):303-324
The South Atlantic passive margin along the south-eastern Brazilian highlands exhibits a complex landscape,including a northern inselberg area and a southern elevated plateau,separated by the Doce River valley.This landscape is set on the Proterozoic to early Paleozoic rocks of the region that once was the hot core of the Aracuai orogen,in Ediacaran to Ordovician times.Due to the break-up of Gondwana and consequently the opening of the South Atlantic during the Early Cretaceous,those rocks of the Araquai orogen became the basement of a portion of the South Atlantic passive margin and related southeastern Brazilian highlands.Our goal is to provide a new set of constraints on the thermo-tectonic history of this portion of the south-eastern Brazilian margin and related surface processes,and to provide a hypothesis on the geodynamic context since break-up.To this end,we combine the apatite fission track(AFT)and apatite(U-Th)/He(AHe)methods as input for inverse thermal history modelling.All our AFT and AHe central ages are Late Cretaceous to early Paleogene.The AFT ages vary between 62 Ma and90 Ma,with mean track lengths between 12.2μm and 13.6μm.AHe ages are found to be equivalent to AFT ages within uncertainty,albeit with the former exhibiting a lesser degree of confidence.We relate this Late Cretaceous-Paleocene basement cooling to uplift with accelerated denudation at this time.Spatial variation of the denudation time can be linked to differential reactivation of the Precambrian structural network and differential erosion due to a complex interplay with the drainage system.We argue that posterior large-scale sedimentation in the offshore basins may be a result of flexural isostasy combined with an expansion of the drainage network.We put forward the combined compression of the Mid-Atlantic ridge and the Peruvian phase of the Andean orogeny,potentially augmented through the thermal weakening of the lower crust by the Trindade thermal anomaly,as a probable cause for the uplift. 相似文献