Potassic and low- and high-Ti mildly alkaline volcanism in the Neoproterozoic Ramada Plateau, southernmost Brazil   总被引：1，自引：0，他引：1  

Carlos Augusto Sommer  Evandro Fernandes de Lima  Lauro Valentim Stoll Nardi  Ana Maria Graciano Figueiredo  Ronaldo Pierosan 《Journal of South American Earth Sciences》2005,18(3-4):237-254

Ramada Plateau Neoproterozoic volcanism represents a portion of the shoshonitic and mildly alkaline magmatism related to postcollisional events of the Brasiliano/Pan African cycle of southernmost Brazil. It is constituted by shoshonitic basic-intermediate lavas, followed by a bimodal sequence characterized by pyroclastic deposits, lava flows, and hypabyssal rocks with ages of 549±5 Ma. The shoshonitic magmatism presents greater K₂O than Na₂O₂, K₂O/Na₂O ratios close to 1, and moderate large ion lithophile and high-field strength element contents. The bimodal basic-acid volcanism presents a transitional chemical affinity with features of sodic, silica-saturated alkaline to continental tholeiitic series. Observed basic and acid rocks with contrasting Ti contents are referred to as high- and low-Ti basalt-rhyolites. Another group of acid rocks with higher Nb, Ta, and Rb values was identified as high-Nb rhyolites. The Ramada Plateau magmatism is comparable to associations related to the final stages of orogenic cycles, in which shoshonitic and high- and low-Ti alkaline magmatism reflects the melting of subduction-modified sources, whereas the high-Nb magmas show less influence of subduction-related metasomatism and are closer to magmas produced from anorogenic sources. A model of magma generation in collisional settings involving slab break-off and asthenospheric upwelling is applied to the evolution of magmatism from subduction-related to anorogenic in the Ramada Plateau.  相似文献   

Institutional responses to climate change: opportunities and barriers for adaptation in the Pantanal and the Upper Paraguay River Basin     

Antonio Augusto Rossotto Ioris  Carlos Teodoro Irigaray  Pierre Girard 《Climatic change》2014,127(1):139-151

Climatic change is expected to have serious impacts on the Pantanal, a large tropical wetland located in the Upper Paraguay River Basin, in the centre of South America, where a range of institutional responses are being developed to mitigate and adapt to climate change. In order to examine the institutional achievements and challenges for managing the region, a specific typology is initially introduced, which comprises a schematic gradient of institutional responses. An empirical analysis was conducted in Brazil, Bolivia and Paraguay, the three countries that share the Pantanal, which identified the hybrid basis of the policy framework under construction, in the sense that it actually combines elements of various institutional responses included in the proposed typology. Important factors that seem to undermine the efficacy of institutional responses in addressing climate change in the region are the strong influence of the agribusiness sector and the still relatively low importance of the Pantanal for national environmental policy-making. This essay makes a claim that the principles of climate justice should guiding policies and interventions as it they constitute the most appropriate strategy to address the inequality and unfairness related to climate change.  相似文献   

The REMO Ocean Data Assimilation System into HYCOM （RODAS_H）： General Description and Preliminary Results          下载免费PDF全文

Clemente Augusto Souza TANAJURA  ;Alex Novaes SANTANA  ;Davi MIGNAC  ;Leonardo Nascimento LIMA  ;Konstantin BELYAEV  ;XIE Ji-Ping 《大气和海洋科学快报》2014,(5):464-470

The first version of the Brazilian Oceano- graphic Modeling and Observation Network （REMO） ocean data assimilation system into the Hybrid Coordi- nate Ocean Model （HYCOM） （RODAS H） has recently been constructed for research and operational purposes. The system is based on a multivariate Ensemble Optimal Interpolation （EnOI） scheme and considers the high fre- quency variability of the model error co-variance matrix. The EnOl can assimilate sea surface temperature （SST）, satellite along-track and gridded sea level anomalies （SLA）, and vertical profiles of temperature （T） and salinity （S） from Argo. The first observing system experiment was carried out over the Atlantic Ocean （78°S-50°N, 100°W-20°E） with HYCOM forced with atmospheric reanalysis from 1 January to 30 June 2010. Five integra- tions were performed, including the control run without assimilation. In the other four, different observations were assimilated： SST only （A SST）; Argo T-S profiles only （AArgo）; along-track SLA only （A_SLA）; and all data employed in the previous runs （A_All）. The A_SST, A_Argo, and A_SLA runs were very effective in improv- ing the representation of the assimilated variables, but they had relatively little impact on the variables that were not assimilated. In particular, only the assimilation of S was able to reduce the deviation of S with respect to ob- servations. Overall, the A_All run produced a good analy- sis by reducing the deviation of SST, T, and S with respect to the control run by 39%, 18%, and 30%, respectively, and by increasing the correlation of SLA by 81%.  相似文献   

Small-scale landfills: impacts on groundwater and soil     

Rodrigo Augusto Bellezoni  Cristiano Kenji Iwai  Vagner Roberto Elis  Wanderley da Silva Paganini  Jorge Hamada 《Environmental Earth Sciences》2014,71(5):2429-2439

In Brazil, the large quantities of solid waste produced are out of step with public policies, technological developments, and government budgets for the division. In small municipalities, the common lack of technological knowledge and financial conditions for suitable waste disposal has resulted in a large number of illegal dumps. Therefore, small sanitary landfill facilities are working with simplified operations focusing on cost reduction and meeting the economic and technological standards of the city without endangering the environment or public health. Currently, this activity is regulated at a federal level although there is some uncertainty regarding the risk of soil and aquifer contamination as theses facilities do not employ liners. Thus, this work evaluates a small landfill to identify changes in soil and groundwater using geotechnical parameters, monitoring wells, and geophysical tests performed by electrical profiling. It is verified that based on current conditions, no contaminants have migrated via underground water aquifers, and overall no significant changes have occurred in the soil. It is concluded that, despite its simplicity, the method investigated is a viable alternative for the final disposal of municipal solid waste from small cities, especially in developing countries.  相似文献