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11.
Alex Souza Sardinha Carlos Eduardo de Mesquita Barros Robert Krymsky 《Journal of South American Earth Sciences》2006,20(4):327-339
The Carajás region, located in the southeastern part of the Amazon Craton, has been considered one of the most important mineral provinces in the world. The Serra do Rabo Granite (SRG) crops out near the eastern termination of the Carajás fault as two granite stocks, elongated approximately in an E–W direction, concordant with the regional structures. Leucomicrocline granite, hornblende–microcline granite, biotite–hornblende–microcline granite, hornblende syenogranite, and subordinate aplite are identified. The granites are grayish pink and coarse to medium grained and have mainly hypidiomorphic granular texture. Granophyric textures are common. The accessory minerals are ilmenite, apatite, zircon, allanite, and rare pyroxene.The SRG rocks are either massive or foliated, with a slightly anastomosed continuous S1 foliation (E–W/subvertical) outlined by the preferred orientation of quartz, feldspars, and mafic minerals. Locally, decimeter- to meter-wide mylonite/ultramylonite bands (S1m) occur along the E–W foliation. The S1 foliation was developed under higher temperatures than those of the S1m mylonite foliation. The SRG structural evolution was controlled by progressive deformation under decreasing temperature, indicative of syntectonic emplacement. The SRG also has relatively high SiO2, K2O, and Na2O contents; high FeO*/(FeO*+MgO) ratios; high Zr, Ba, Nb, and Ga; and very high rare-earth element contents. The chemical signature is moderately alkaline and metaluminous, comparable to that of the A-type, A2, and ALK-3 granites. The origin of the SRG magmas may be related to the partial melting of crustal sources, such as previously metamorphosed calc-alkaline granites.The SRG crosscuts supracrustal rocks, promoting low-pressure/high-temperature metamorphism. The interaction between regional compressive stresses and the ballooning effect of the granite stocks promoted slight aureole flattening and rheological changes in the supracrustal rocks. The U–Pb zircon age of 2743±1.6 Ma is interpreted as the age of zircon crystallization, granite stock emplacement, and regional horizontal shortening. Other 2.7 Ga syntectonic alkaline granites (e.g. Estrela, Plaquê, Planalto) have been reported in the region. 相似文献
12.
Yara Schaeffer-Novelli Hilda de Souza Lima Mesquita Gilberto Cintrón-Molero 《Estuaries and Coasts》1990,13(2):193-203
The Cananéia Lagoon estuarine system lies at 25°S, near the latitudinal limit for mangroves. It is 110 km long, consisting of 1–3 km wide channels behind a barrier island, with narrow inlets at the southern and northern ends. Average and maximum depths are 6 m and 12 m. The system is microtidal and subtropical. Mean annual temperature is 21.4°C (annual amplitude=7.0°C). When the area receives sporadic frosts, temperatures close to 2°C occur in the estuary. Annual precipitation (2,270 mm) exceeds annual potential evapotranspiration (1,656 mm). The water budget of the 1,339 km2 watershed is controlled primarily by local rainfall. Before 1978, a large river discharged a significant portion of its flow into the lagoon, but closure of the diversionary channel has since caused changes in salinity, phytoplankton populations, and mangrove coverage. About 90 km2 of intertidal habitat is occupied by mangroves and tidal marsh; mangroves are dominant. Fringe and riverine forests (dominated byRhizophora) are more structurally developed than the basins dominated byLaguncularia and have higher litterfall rates (2.08 g m?2 d?1, fringes; 1.04 g m?2d?1, basins). Primary production exhibits pronounced seasonal pulses; heterotrophic processes lag photosynthetic production and are partially driven by particulate matter inputs. Synthetic models must consider the spatial and temporal heterogeneity of this region. 相似文献
13.
João A. Hackerott Mostafa Bakhoday Paskyabi Joachim Reuder Amauri P. de Oliveira Stephan T. Kral Edson P. Marques Filho Michel dos Santos Mesquita Ricardo de Camargo 《Boundary-Layer Meteorology》2017,165(2):211-231
We discuss scalar similarities and dissimilarities based on analysis of the dissipation terms in the variance budget equations, considering the turbulent kinetic energy and the variances of temperature, specific humidity and specific CO\(_2\) content. For this purpose, 124 high-frequency sampled segments are selected from the Boundary Layer Late Afternoon and Sunset Turbulence experiment. The consequences of dissipation similarity in the variance transport are also discussed and quantified. The results show that, for the convective atmospheric surface layer, the non-dimensional dissipation terms can be expressed in the framework of Monin–Obukhov similarity theory and are independent of whether the variable is temperature or moisture. The scalar similarity in the dissipation term implies that the characteristic scales of the atmospheric surface layer can be estimated from the respective rate of variance dissipation, the characteristic scale of temperature, and the dissipation rate of temperature variance. 相似文献
14.
Smail Slimani Nicolas Massei Johanna Mesquita Danièle Valdés Matthieu Fournier Benoît Laignel Jean-Paul Dupont 《Hydrogeology Journal》2009,17(8):1823-1832
The temporal variability of water-level fluctuations in the chalk aquifer of Upper Normandy, France is constrained by natural climate fluctuations and is closely linked to the regional geological patterns. The chalk plateaus are covered with 5–50 m thick semi-permeable surficial formations; the thickness of the underlying chalk aquifer varies from 50 to 300 m. The relationship among climate oscillations, piezometric levels, and geologic structure were investigated by correlation, Fourier spectral, and continuous wavelet analyses of selected piezometric time-series data. Analysis focused on two piezometers located on the uplifted side of a major fault and two piezometers on the downthrown side. After generalization to other piezometers in the region, it was deduced that, in the downthrown compartments, a substantial aquifer and surficial formations thickness would imply a strong attenuation of annual variability, while multi-year variability is clearly expressed. Conversely, in the uplifted compartments, a thin layer of surficial formations and small thickness of the chalk authorizes strong variations on the annual mode with respect to the contribution of long-term climatic oscillations (multi-year variability). The results then demonstrated—and proposed a spatial determination of—the differential influence of geological patterns on the filtering of climate-induced oscillations in piezometric variability. 相似文献
15.
Marta Rodrigues Anabela Oliveira Martha Guerreiro André Bustorff Fortunato José Menaia Luís Mesquita David Alexandra Cravo 《Ocean Dynamics》2011,61(6):841-856
This study aims at understanding the fecal contamination behavior in a small coastal stream (Aljezur, Portugal), which has
significant economic and ecological values. Like in most small coastal systems, circulation and water renewal in the Aljezur
stream exhibit a strong variability due to their dependence on tides, waves, intermittent river flows, and a highly variable
morphology. Hence, the problem was approached through a combination of field surveys and the development and application of
a hard-coupled three-dimensional hydrodynamic and fecal contamination model. Salinity and temperature results have shown that
mixing and transport in the stream are very sensitive to the river flow and wind forcing. The model is able to represent the
main patterns and trends observed in Escherichia coli and fecal enterococcus concentrations along the stream, for different environmental and contamination conditions, suggesting
die-off rates on the order of 0.50–0.55 day−1. Die-off rate and the representation of the sediment-associated processes were identified as the major remaining sources
of uncertainty in the model. Results show that, owing to the processes that occur along the stream, fecal bacteria reach the
beaches water in numbers that comply with the European Bathing Waters Directive, even during the summer periods when the upstream
concentrations are larger. In particular, results suggest a direct relation between the tidal propagation upstream and the
reduction of the fecal bacteria concentrations along the stream that can be relevant for the development of a strategy for
the management of the system’s water safety. 相似文献