958 resultados para Congo Fan


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Individual planktonic microfossil species, or assemblage groups of different species, are often used to, qualitatively and/or quantitatively, reconstruct past (sub)surface-water conditions of the world's oceans and seas. Until now, little information has been available on the surface sediment distribution patterns and paleoenvironmental reconstruction potential of coccolith, calcareous dinoflagellate cyst and organic-walled dinoflagellate cyst assemblages of the South and equatorial Atlantic, especially at the species level. This paper (i) summarizes the distributions of these three phytoplanktonic microfossil groups in numerous Atlantic surface sediments from 20°N-50°S and 30°E-65°W and determines their relationship with the physicochemical and trophic conditions of the overlying (sub)surface-waters, and (ii) determines the synecology of the three phytoplankton groups by carrying out statistical analyses (i.e. detrended and canonical correspondence analyses) on all groups simultaneously. Ecological relationships are additionally strengthened by statistically comparing the distribution patterns of the phytoplankton groups with those of planktonic foraminifera (Pflaumann et al. 1996; Niebler et al. 1998), as the ecological preferences of the latter are much better known. Many of the analyzed phytoplanktonic microfossil species or groups of species in the surface sediments do show restricted distributions which primarily reflect the environmental conditions of the upper water masses above them (e.g. sea-surface temperature, productivity, stratification). The acquired 'reference' data sets are large and diverse enough to allow future development of transfer functions for the reconstruction of past surface-water conditions, and show that there is still an enormous paleoenvironmental reconstruction potential concealed in many fossil coccolith and dinoflagellate cyst assemblages.

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Surface samples, mostly from abyssal sediments of the South Atlantic, from parts of the equatorial Atlantic, and of the Antarctic Ocean, were investigated for clay content and clay mineral composition. Maps of relative clay mineral content were compiled, which improve previous maps by showing more details, especially at high latitudes. Large-scale relations regarding the origin and transport paths of detrital clay are revealed. High smectite concentrations are observed in abyssal regions, primarily derived from southernmost South America and from minor sources in Southwest Africa. Near submarine volcanoes of the Antarctic Ocean (South Sandwich, Bouvet Island) smectite contents exhibit distinct maxima, which is ascribed to the weathering of altered basalts and volcanic glasses. The illite distribution can be subdivided into five major zones including two maxima revealing both South African and Antarctic sources. A particularly high amount of Mg- and Fe-rich illites are observed close to East Antarctica. They are derived from biotite-bearing crystalline rocks and transported to the west by the East Antarctic Coastal Current. Chiorite and well-crystallized dioctaedral illite are typical minerals enriched within the Subantarctic and Polarfrontal-Zone but of minor importance off East Antarctica. Kaolinite dominates the clay mineral assemblage at low latitudes, where the continental source rocks (West Africa, Brazil) are mainly affected by intensive chemical weathering. Surprisingly, a slight increase of kaolinite is observed in the Enderby Basin and near the Filchner-Ronne Ice shelf. The investigated area can be subdivided into ten, large-scale clay facies zones with characteristic possible source regions and transport paths. Clay mineral assemblages of the largest part of the South Atlantic, especially of the western basins are dominated by chlorite and illite derived from the Antarctic Peninsula and southernmost South America and supported by advection within the Circumantarctic Deep Water flow. In contrast, the East Antarctic provinces are relatively small. Assemblages of the eastern basins north of 30°S are strongly influenced by African sources, controlled by weathering regimes on land and by a complex interaction of wind, river and deep ocean transport. The strong gradient in clay mineral composition at the Brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins.

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A 20 kyr long sediment sequence from the Congo deep sea fan (core GeoB 6518-1), one of the world's largest deep sea river fans, has been analysed for bulk and molecular proxies in order to reconstruct the marine, soil and plant organic carbon (OC) contributions to these sediments since the last glacial maximum. The bulk proxies applied, C/N ratio and d13Corg, ranged from 10 to 12.5 and from -24.5 to -21 per mill VPDB, respectively. As molecular proxies, concentrations of marine derived alkenones and terrestrial derived odd-numbered n-alkanes were used, which varied between 0.2 and 4 µg/g dry weight sediment. In addition, the branched vs. isoprenoid tetraether (BIT) index, a proxy for soil organic matter input, was used, which varied from 0.3 to 0.5 in this core. Application of binary mixing models, based on the different individual proxies, showed estimates for terrestrial OC input varying by up to 50% due to the heterogeneous nature of the OC. Application of a three end-member mixing model using the d13Corg content, the C/N ratio and the BIT index, enabled the distinction of soil and plant organic matter as separate contributors to the sedimentary OC pool. The results show that marine OC accounts for 20% to 40% of the total OC present in the deep sea fan sediments over the last 20 kyr and that soil OC accounts for about half (45% on average) of the OC present. This suggests that soil OC represents the majority of the terrestrial OC delivered to the fan sediments. Accumulation rates of the plant and soil OC fractions over the last 20 kyr varied by a factor of up to 5, and are strongly related to sediment accumulation rates. They showed an increase starting at ca. 17 kyr BP, a decline during the Younger Dryas, peak values during the early Holocene and lower values in the late Holocene. This pattern matches with reconstructions of past central African humidity and Congo River discharge from the same core and revealed that central African precipitation patterns exert a dominant control on terrestrial OC deposition in the Congo deep sea fan. Marine OC accumulation rates are only weakly related to sediment accumulation rates and vary only little over time compared to the terrigenous fractions. These variations are likely a result of enhanced preservation during times of higher sedimentation rates and of relative small fluctuations in primary production due to wind-driven upwelling.

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Numerous studies use major element concentrations measured on continental margin sediments to reconstruct terrestrial climate variations. The choice and interpretation of climate proxies however differ from site to site. Here we map the concentrations of major elements (Ca, Fe, Al, Si, Ti, K) in Atlantic surface sediments (36°N-49°S) to assess the factors influencing the geochemistry of Atlantic hemipelagic sediments and the potential of elemental ratios to reconstruct different terrestrial climate regimes. High concentrations of terrigenous elements and low Ca concentrations along the African and South American margins reflect the dominance of terrigenous input in these regions. Single element concentrations and elemental ratios including Ca (e.g., Fe/Ca) are too sensitive to dilution effects (enhanced biological productivity, carbonate dissolution) to allow reliable reconstructions of terrestrial climate. Other elemental ratios reflect the composition of terrigenous material and mirror the climatic conditions within the continental catchment areas. The Atlantic distribution of Ti/Al supports its use as a proxy for eolian versus fluvial input in regions of dust deposition that are not affected by the input of mafic rock material. The spatial distributions of Al/Si and Fe/K reflect the relative input of intensively weathered material from humid regions versus slightly weathered particles from drier areas. High biogenic opal input however influences the Al/Si ratio. Fe/K is sensitive to the input of mafic material and the topography of Andean river drainage basins. Both ratios are suitable to reconstruct African and South American climatic zones characterized by different intensities of chemical weathering in well-understood environmental settings.

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This study used the Sport Interest Inventory (SII) to examine the motivation of fans attending a game in the Australian Football League. This is the first study to use the SII for professional men’s team sport outside the United States. Confirmatory factor analysis showed the model provided a good fit for the data collected in Australia, and regression analysis revealed that team interest, vicarious achievement, excitement and player interest were the significant factors in predicting and explaining the level of attitudinal loyalty of fans toward their favourite team.

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One of the features of the sporting industry is the ritualized way in which it is consumed across the world. Fans of every sport have rituals and superstitions to help them enjoy the spectacle, socialize with other like-minded fans, and reduce some of the anxiety of watching their team play. These rituals include dress, barracking styles and pre and post match behaviors. What is not known are the factors that lead fans to engage in ritual behaviors and what relationship rituals have with desirable outcomes such as increased attendance, attitudinal loyalty or satisfaction. Given that some ritual behaviors are clearly undesirable, (e.g., hooliganism), understanding these relationships is important to managers who may be questioning whether rituals should be encouraged. Although ritualized behavior amongst fans is clearly visible, the symbolic and emotional nature of ritual poses challenges to researchers. Most previous ritual research is exploratory and qualitative in nature. This study, however, uses a behavior-based scale to measure fan ritual and relates it to desirable outcomes such as commitment and attendance. Over 2,000 season ticket holders of a football (soccer) team in Australia’s professional A-League competition were surveyed to investigate the antecedents and consequences of fan ritual behavior. Cluster analysis was used to explore the characteristics of respondents, and it revealed that those fans that engage in ritual behavior also differed on many other demographic and attitudinal dimensions. The associations between ritual and psychological commitment, and ritual and attendance are positive and significant. When used in conjunction with other constructs, fan ritual also improves the explanation of attendance behavior. The findings support previous research that found a significant and positive relationship between team identification, involvement and attendance, and extend previous research by finding a significant and positive relationship between rituals and attendance. For sports marketing practitioners, the results indicate the importance of developing and managing consumption rituals tied to game day attendance, with a view to generating uncommon loyalty.

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The social construction of sexuality over the past one hundred and fifty years has created a dichotomy between heterosexual and non-heterosexual identities that essentially positions the former as “normal” and the latter as deviant. Even Kinsey’s and others’ work on the continuum of sexualities did little to alter the predominantly heterosexist perception of the non-heterosexual as “other” (Kinsey, Pomeroy and Martin 2007; Esterberg 2006; Franceour and Noonan 2007). Some political action and academic work is beginning to challenge such perceptions. Even some avenues of social interaction, such as the recent proliferation of online communities, may also challenge such views, or at least contribute to their being rethought in some ways. This chapter explores a specific kind of online community devoted to fan fiction, specifically homoerotic – or what is known colloquially as “slash” – fan fiction. Fan fiction is fiction, published on the internet, and written by fans of well-known books and television shows, using the characters to create new and varied plots. “Slash” refers to the pairing of two of the male characters in a romantic relationship, and the term comes from the punctuation mark dividing the named pair as, for example, Spock/Kirk from the Star Trek television series. Although there are some slash fan-fiction stories devoted to female-female relationships – called “femmeslash” – the term “slash” generally refers to male-male relationships, and will be utilized throughout this chapter, given that the research discussed focuses on communities centered around one such male pairing.

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Rituals are an important part of society, and are a frequent topic of investigation among sociologists and anthropologists. Marketing applications of ritual, however, are rare. This study investigates the relationships between sports fan rituals, team identification and attendance using the Fan Ritual Scale. Data were collected at a professional football game in Australia. The results reveal a significant and positive relationship between social rituals, identification and attendance. There was no relationship however, between identification, attendance and personal rituals.