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131.
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Sébastien Nomade Jean-François Pastre Alison Pereira Alexandra Courtin-Nomade Vincent Scao 《Comptes Rendus Geoscience》2017,349(2):71-80
Since the 1960s, an early explosive activity in the Mont-Dore Massif is associated with a major pyroclastic rhyolitic eruption (5–7 km3) known as the “Grande Nappe” (GN). This event, linked to the formation of a 6-km-diameter cryptic caldera named “Haute Dordogne”, was before our investigation dated by 40Ar/39Ar at 3.07 ± 0.04 Ma. Our new single-crystal laser fusion 40Ar/39Ar dates obtained on two outcrops of the GN (Rochefort-Montagne and Ludières) questioned several hypotheses made concerning this “landmark” event of the Mont-Dore Massif history. We demonstrate that: (1) the GN rhyolitic eruption has occurred much later than previously estimated (i.e. 2.77 ± 0.02–0.07 Ma full external uncertainties); (2) the correlation made between the Vendeix rhyolitic complexes (intra-caldera position) dated back to 2.74 ± 0.04 Ma and the GN is proposed; (3) xenocryst contamination could be very high (i.e. 70% for the Rochefort-Montagne GN outcrop) and explains the noticeable older age obtained previously; (4) a link between the GN eruption and the formation of a caldera is questionable; the hypothesis of a northward-oriented blast channeled eastward toward the paleo-Allier River is thus proposed. 相似文献
133.
Spatial distribution of metals in sediments of the Ribeira Bay, Angra dos Reis, Rio de Janeiro, Brazil 总被引:1,自引:0,他引:1
N.V. Freret-Meurer J.V. Andreata B.C. Meurer F.V. Manzano M.G.S. Baptista D.E. Teixeira M.M. Longo 《Marine pollution bulletin》2010,60(4):627-629
This study aims to analyze the spatial distributions of several metals in sediments from five sites in Ribeira Bay, Brazil. Ribeira Bay is a very important area to the local community, due to its artisan fishery, and it also has a biological relevance for many marine species that use mangroves as nursery and feeding sites. According to the results, the area was not considered a metal polluted area. Despite not having a significant source of metals inside the Bay nowadays, Ilha Grande Bay harbors a shipyard, an oil terminal, and a commercial port, as well as two thermonuclear power plants (Angra I e II), all of which indirectly influence the study area. 相似文献
134.
Dmitry A. Ruban Henrique Zerfass Vladimir I. Pugatchev 《Journal of South American Earth Sciences》2009,28(2):155-167
Global tracing of the key surfaces of Triassic deposits may contribute significantly to the understanding of the common patterns in their accumulation. We attempt to define synthems – disconformity-bounded sedimentary complexes – in the Triassic successions of southern South America (southwestern Gondwana, Brazil and Argentina) and the Western Caucasus (the northern Neotethys, Russia), and then to trace their boundaries in the adjacent regions and globally. In southern South America, a number of synthems have been recognized – the Cuyo Basin: the Río Mendoza–Cerro de las Cabras Synthem (Olenekian–Ladinian) and the Potrerillos–Cacheuta–Río Blanco Synthem (Carnian–Rhaetian); the Ischigualasto Basin: the Ischichuca-Los Rastros Synthem (Anisian–Ladinian) and the Ischigualasto–Los Colorados Synthem (Carnian–Rhaetian); the Chaco–Paraná Basin: the Sanga do Cabral Synthem (Induan), the Santa Maria 1 Synthem (Ladinian), the Santa Maria 2 Synthem (Carnian), and the Caturrita Synthem (Norian); western Argentina: the Talampaya Synthem (Lower Triassic) and the Tarjados Synthem (Olenekian?). In the Western Caucasus, three common synthems have been distinguished: WC-1 (Induan–Anisian), WC-2 (uppermost Anisian–Carnian), and WC-3 (Norian–lower Rhaetian). The lower boundary of WC-1 corresponds to a hiatus whose duration seems to be shorter than that previously postulated. The synthem boundaries that are common to southwestern Gondwana and the Western Caucasus lie close to the base and top of the Triassic. The Lower Triassic, Ladinian, and Upper Triassic disconformities are traced within the studied basins of southern South America, and the first two are also established in South Africa. The Upper Triassic disconformity is only traced within the entire Caucasus, whereas all synthem boundaries established in the Western Caucasus are traced partly within Europe. In general, the synthem boundaries recognized in southern South America and the Western Caucasus are correlated to the global Triassic sequence boundaries and sea-level falls. Although regional peculiarities are superimposed on the appearance of global events in the Triassic synthem architecture, the successful global tracing suggests that planetary-scale mechanisms of synthem formation existed and that they were active in regions dominated by both marine and non-marine sedimentation. 相似文献
135.
Renata J. Romanowicz Peter C. Young Keith J. Beven Florian Pappenberger 《Advances in water resources》2008
Operational flood forecasting requires accurate forecasts with a suitable lead time, in order to be able to issue appropriate warnings and take appropriate emergency actions. Recent improvements in both flood plain characterization and computational capabilities have made the use of distributed flood inundation models more common. However, problems remain with the application of such models. There are still uncertainties associated with the identifiability of parameters; with the computational burden of calculating distributed estimates of predictive uncertainty; and with the adaptive use of such models for operational, real-time flood inundation forecasting. Moreover, the application of distributed models is complex, costly and requires high degrees of skill. This paper presents an alternative to distributed inundation models for real-time flood forecasting that provides fast and accurate, medium to short-term forecasts. The Data Based Mechanistic (DBM) methodology exploits a State Dependent Parameter (SDP) modelling approach to derive a nonlinear dependence between the water levels measured at gauging stations along the river. The transformation of water levels depends on the relative geometry of the channel cross-sections, without the need to apply rating curve transformations to the discharge. The relationship obtained is used to transform water levels as an input to a linear, on-line, real-time and adaptive stochastic DBM model. The approach provides an estimate of the prediction uncertainties, including allowing for heterescadasticity of the multi-step-ahead forecasting errors. The approach is illustrated using an 80 km reach of the River Severn, in the UK. 相似文献
136.
测绘遥感信息工程国家重点实验室十年建设与创新 总被引:1,自引:0,他引:1
回顾了测绘遥感信息工程国家重点实验室自1989年建室以来10年的历程,重点展示了10年来的研究成果,成果产品化、人才培养与对外开放方面所做的工作。在总结经验的基础上提出了国家重点实验室的发展必须抓好5个方面的工作,对同类实验室建设具有一定的借鉴价值。 相似文献
137.
矿床中镉元素异常明显,以硫镉矿、不规则粒状、脉状充填嵌布于闪锌矿中。提出矿石生成顺序,为进一步找矿提供新依据。 相似文献
138.
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140.
冻土工程国家重点实验室的回顾与展望 总被引:7,自引:2,他引:5
冻土工程国家重点实验室是我国唯一的一个以冻土工程为主要研究内容的综合性实验室,其建设和发展对促进我国冻土学的发展有非常重要的意义,在迎来兰州冰川冻土研究所建所40周年之际,冻土工程国家重点实验室也走过了近9年的历程,回顾昨天,展望未来,只有紧紧把握粘土学科前沿,创新超前,解决国家在寒区经济和社会发展中提出的基础性,关键性和综合性的工程和资源环境问题,才能创建一流的国家重点实验室,使我国冻土工程研究 相似文献