The Common Origin of the High Inclination TNO's     

Gomes  Rodney 《Earth, Moon, and Planets》2003,92(1-4):29-42

Numerical integrations of the four major planets orbits inside a primordialplanetesimals disk show that a fraction of Neptune primordial scatteredobjects are deposited into the classical Kuiper Belt at Solar System age. Theseobjects exhibit inclinations as high as 40° and can account forpresent high inclinations population in the classical Kuiper Belt. The samemechanism can also originate high perihelion scattered objects like 2000 CR₁₀₅. The process that in the end produced such objects can be divided into two phases, a migration phase where nonconservative dynamics acted to producesome stable objects already at 10⁸ years and a nonmigrating phase that helped to establish some other objects as stable TNO's. Low inclination CKBO's have inprinciple an origin through the resonance sweeping process, although someresults from numerical integrations at least suggest a possible origin also fromthe primordial Neptune scattered population.  相似文献   

Carbonatites from Eastern Paraguay and genetic relationships with potassic magmatism: C, O, Sr and Nd Isotopes     

F. Castorinal  P. Censi  P. Comin-Chiaramonti  E. M. Piccirillo  A. Alcover Neto  C. B. Gomes  T. I. Ribeiro de Almeida  S. Speziale  M. C. M. Toledo 《Mineralogy and Petrology》1997,61(1-4):237-260

Summary Geochemical characteristics were systematically determined for Early Cretaceous samples of carbonatitic rocks from Eastern Paraguay (Rio Apa, Amambay and Central Provinces). The data show that all the occurrences have an enriched isotopic signature and that the carbonatites have negligible or absent crustal signature. A petrogenetic model (parent liquids, fractional crystallization, hydrothermal interactions and weathering) is proposed as a function of incompatible trace element, stable (O-C) and radiogenic (Sr-Nd) isotope variations with the aim to test the significance of carbonatitic complexes as a marker of the metasomatized subcontinental lithospheric mantle. The results indicate that the carbonatites and primary carbonates from eastern Paraguay, and those from the north eastern Paraná Basin (SE Brazil), were affected by metasomatic events distinct in time and composition.

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Karbonatite aus Ost-Paraguay und ihre genetische Beziehung zu Kalium-Magmatismus: C O, Sr und Nd isotope

Zusammenfassung Die geochemischen Charakteristika von frühkretazischen Karbonatitproben aus Ostparaguay (Rio Alpa, Amambay und Zentrale Provinzen) wurden untersucht. Die Daten belegen, daß alle Vorkommen eine isotopische Anreicherungssignatur zeigen und daß ihnen eine entsprechende Krustensignatur fehlt. Ein Petrologisches Modell (Ausgangsschmelze, fraktionierte Kristallisation, hydrothermale Interaktion und Verwitterung) wird auf Grund der Verteilung der inkompatiblen Spurenelemente, der stabilen (C-O) und radiogenen (Sr-Nd) Isotope vorgeschlagen. Es versucht die Bedeutung der Karbonatitkomplexe als Markerhorizonte des metasomatischen subkontinentalen Mantels zu überprüfen. Die Ergebnisse zeigen, daß die Karbonatite und die primären Karbonate in Ostparaguay, und jene aus dem Paraná Becken SüdostBrasiliens durch zeitlich und zusammensetzungsmäßig unterschiedliche metasomatische Prozesse erfaßt wurden.

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With 10 Figures  相似文献   

Geochemistry of Coexisting Biotite and Muscovite of Portuguese Peraluminous Granitic Differentiation Series     

A.M.R. Neiva  M.M.V.G. Silva  M.E.P. Gomes  T.F.C. Campos 《Chemie der Erde / Geochemistry》2002,62(3):197-215

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An adaptive finite element model for wellbore breakout simulation     

Diogo L. Cecílio  Philippe R. B. Devloo  Sônia M. Gomes  Erick S.R. Santos 《国际地质力学数值与分析法杂志》2019,43(4):814-828

A finite element formulation is proposed and implemented for analysing the stability of excavated wells using the DiMaggio-Sandler constitutive elastoplastic model with a typical carbonate reservoir configuration. The quality of the finite element approximation is ensured by applying smooth curved elements adapted to the wellbore geometry, and h − p adaptive finite element meshes in the plastic zone. General purpose procedures are defined to transfer the elastoplastic deformation history to newly created integration points. A breakout damage criterion is proposed based on the second invariant of the deviatoric plastic deformation tensor. This damage criterion is used to apply a mesh movement algorithm to represent material collapse. The automatic successive application of the breakout damage criterion results in elliptical realistically looking geometries obtained in experiments reported in the literature.  相似文献   

A local-scale approach to estuarine flood risk management   总被引：1，自引：0，他引：1  

Paula Freire  Alexandre O. Tavares  Luís Sá  Anabela Oliveira  André B. Fortunato  Pedro P. dos Santos  Ana Rilo  João L. Gomes  João Rogeiro  Rui Pablo  Pedro J. Pinto 《Natural Hazards》2016,84(3):1705-1739

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Distribution and feeding modes of macrobenthos within three oceanographic feature areas of the KwaZulu-Natal Bight,South Africa     

CB Untiedt 《African Journal of Marine Science》2016,38(1):S91-S104

The composition and distribution of macrobenthic communities was investigated in three areas in the KwaZulu- Natal Bight, a section of shelf off the east coast of South Africa. Areas were pre-selected on the basis of three known oceanographic features, posited to deliver land- or Agulhas Current-derived nutrients onto the shelf and to drive ecosystem functioning in this region. Replicate sediment samples were collected with a 0.2 m² van Veen grab, during two surveys (A, B) corresponding with normal periods of high and low rainfall, respectively. A subset of the full station array was selected across the shelf in an arrangement of increasing depths (inner-, mid- and outer shelf) through each feature area to investigate the spatial distribution and feeding modes of macrobenthic taxa. The two periods showed some differences in abundance and numbers of macrobenthic taxa, but were not statistically different. Total macrobenthic abundance from Survey A was 20 215 individuals from 642 taxa, decreasing to 18 000 individuals from 503 taxa during Survey B. Polychaeta and Crustacea were the dominant taxa sampled; abundance of the latter was attributed largely to a proliferation of Paguristes sp.1 at inner-shelf samples in the midbight (Thukela) region during Survey B. Similarity classification distinguished seven sample groups reflecting differences in feature areas and shelf positions under investigation. The Thukela River midshelf community supported the highest macrobenthic abundance, while the midshelf off the southern bight (Durban region) was most species rich. Findings were attributed to the habitat complexity of the midshelf which includes a palaeo-dune cordon at the 60 m isobath. Functionally, the community was dominated by interface- and deposit-feeding fauna, emphasising the importance of trophic plasticity in an environmentally variable and heterogeneous shelf environment.  相似文献   

Hydrologic models coupled with 2D hydrodynamic model for high-resolution urban flood simulation     

de Arruda Gomes  Mayara Maria  de Melo Verçosa  Lívia Fragoso  Cirilo  José Almir 《Natural Hazards》2021,108(3):3121-3157

Natural Hazards - Floods are the most frequent natural disaster and pose a very challenging threat to many cities worldwide. Understanding the flood dynamic is essential for developing strategies...  相似文献   

南非开普省北部金伯利岩侵位的年代     

Smit.  CB 《国土资源信息化》1989,(1):21-23

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Occurrence and Resistance of Pathogenic Bacteria Along the Tietê River Downstream of São Paulo in Brazil     

Wolf-Rainer Abraham  Alexandre José Macedo  Luiz Humberto Gomes  Flavio C. A. Tavares 《洁净——土壤、空气、水》2007,35(4):339-347

The load of pathogenic bacteria, their fate and their dangerousness in the Tietê River were assessed along 100 km starting from the city of São Paulo, Brazil. The data were compared with those from two German rivers. High loads of pathogens were found in the Tietê River near the city of São Paulo (Escherichia coli O157:H7, Shigella flexneri, and Shigella boydii), which were absent 30 km downstream of São Paulo. The antibiotic resistances observed in the Tietê river were rather low and decreased after the major input in São Paulo to significantly lower levels about 30 km downstream. While the Brazilian isolates were more susceptible for ampicillin than the German ones, the reverse was observed for gentamycin. For optimal control of infections in humans critical areas where these bacteria survived longer and their elimination mechanisms should be identified as well as the extent and the origin of antibiotic resistance should be determined.  相似文献   

Pyroxenes and olivines as indicators of the petrological evolution of the Ivrea-Verbano basic formation (Italian Western Alps)     

Prof. S. Capedri  Prof. C. B. Gomes  Prof. G. Rivalenti  Dr. E. Ruberti 《Mineralogy and Petrology》1976,23(3):175-190

Summary Microprobe analyses of olivines, orthopyroxenes and clinopyroxenes of the Ivrea-Verbano basic formation reveal that in the Balmuccia Periodotites (regarded as residual mantle) the phases are more magnesian than in the overlaying ultramafic-mafic series (interpreted as a cumulitic complex formed by fractionation of mantle-derived magma).Pyroxenes underwent sub-solidus re-equilibration. Whole phase (host + exsolved lamellae) compositions give a temperature in the range 946°C–1236°C, compatible with the igneous crystallisation. The compositions of the host phases give temperatures in the range 712°C to 919°C, indicating that the samples did not attain the same degree of equilibrium during the sub-solidus unmixing. The sub-solidus unmixing of the pyroxenes may have occurred either during the superimposed granulite-facies metamorphism or during the slow cooling of the complex intruded into deep crustal levels.

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Pyroxene und Olivine als Indikatoren der petrologischen Entwicklung der basischen Formation von Ivrea-Verbano (Italienische Westalpen)

Zusammenfassung Mikrosondenanalysen von Olivinen, Orthopyroxenen und Klinopyroxenen der basischen Formation von Ivrea-Verbano zeigen, daß in den Balmuccia Peridotiten (die als residuales Mantelmaterial angesehen werden) die Phasen Mg-reicher sind als in den überlagernden ultramafischen bis mafischen Serien (die als Kumulationskomplex gedeutet werden, der durch Fraktionierung eines aus dem Mantel stammenden Magmas gebildet wurde).Die Pyroxene wurden unter Subsolidus-Bedingungen reequilibriert. Die Zusammensetzungen der Gesamtphasen (Wirt + Entmischungslamellen) geben Temperaturen im Bereich von 946–1236°C, was mit einer magmatischen Kristallisation verträglich ist. Die Zusammensetzungen der Wirt-Phasen geben Temperaturen im Bereich von 712–919°C an, was anzeigt, daß die Proben während der Subsolidus-Entmischung nicht denselben Grad der Equilibirierung erreichten. Die Subsolidus-Entmischung der Pyroxene kann entweder während der überlagerten Metamorphose in Granulitfazies oder während der langsamen Abkühlung des in tiefe Krustenschichten intrudierten Komplexes geschehen sein.

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With 4 Figures  相似文献