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Abstract: The Balfour Formation has a pronounced lithological variation that is characterized by alternating sandstone- and mudstone-dominated members. The sandstone-dominated Oudeberg and Barberskrans Members are composed of lithofacies that range from intraformational conglomerates to fine-grained sediments, whereas the mudstone-dominated members (Daggaboersnek, Elandsberg, and Palingkloof) are dominated by the facies Fm and Fl. Petrography, geochemistry, and a paleocurrent analysis indicated that the source rock of the Balfour Formation was to south east and the rocks had a transitional/dissected magmatic arc signature. The sandstones-rich members were deposited by seasonal and ephemeral high-energy, low-sinuous streams, and the fine-grained-rich members were formed by ephemeral meandering streams. The paleoclimates have been equated to present temperate climates; they were semiarid becoming arid towards the top of the Balfour Formation. This has been determined by reconstructing the paleolatitude of the Karoo Basin, geochemistry, paleontology, sedimentary structures, and other rock properties, like color. 相似文献
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1 Introduction The Gaojiacun intrusive complex is one of the numerous ultramafic-mafic intrusions in Sichuan Province of China. It was mapped during the 1970s and studied mainly by Chinese scientists (e.g. Geological Team 106, 1975; Shen et al., 1986, 1989; CGGJC, 1986; Yang et al., 1993; Li et al., 1995; Shen et al., 2003; Zhu et al., 2004a). Since the year 2000, China has become one of the largest PGE consumers. While the country can produce only less than 1 ton PGE/year, the Chin… 相似文献
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A number of cyclic triaxial tests were carried out on mine tailings and natural sediment samples under undrained conditions
to investigate their resistance to cyclic loading. The tests were performed on more than 100 samples with a cyclic shear stress
ratio ranging from 0.10 to 0.40 under varying void ratio and the same confining pressure. It was observed that the axial strain
and excess pore water pressure increased with the number of loading cycles while the effective stress decreased with increasing
number of loading cycles. The liquefaction resistance of the tailings was also observed to be higher than that of natural
soils with similar particle size distribution, void ratio and plasticity index. It was observed that the influence of specific
gravity on the cyclic strength of mine tailings is significant. The results showed that the cyclic resistance of the tailings
was not strongly influenced by plasticity index for low plasticity tailings. A boundary relationship between void ratio and
normalized cyclic resistance ratio was established based on the results. 相似文献
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Bernardi Mara S. Africa Pasquale C. de Falco Carlo Formaggia Luca Menafoglio Alessandra Vantini Simone 《Mathematical Geosciences》2021,53(8):1781-1812
Mathematical Geosciences - Recent advances in satellite technologies, statistical and mathematical models, and computational resources have paved the way for operational use of satellite data in... 相似文献
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On the basis of a 2008 survey conducted in the Msunduzi municipality in the KwaZulu-Natal province, the paper begins an exploration of the character of popular politics and citizenship in South Africa. Embracing a ‘citizen-centred’ methodology informed by participation literatures, and sensibilities to the ‘work in progress’ character of African cities from urban studies debates, the paper interrogates the mainstream liberal-participatory model of citizenship in South Africa, and the critiques of current South African politics informed by these notions, specifically the ‘racial census’ and ‘dominant party syndrome’ analyses. Taken together these views can be read as characterising South African politics as a game for individual citizens governed by liberal rules, but played by racial and/or partisan groups in exclusionary ways, thus distorting liberal democratic mechanisms of representation and accountability. The paper also examines evidence for an alternative class-based analysis of one aspect of citizenship, namely, protest against poor local governance.The paper looks to unpack this ‘liberal model versus racialised communitarian practice’ imaginary by, on the one hand, demonstrating the ways in which citizenship is not racialised, or is asymmetrically racialised. Indeed, other than party allegiances and trust in key offices, very little by way of what citizens do, believe or think of themselves follows discrete racial lines. Similar points hold for partisanship too. On the other hand, the paper does not redeem the liberal-democratic model as there is also evidence of trust in government when it is not deserved based on performance, but more importantly, evidence that citizens embrace ‘informal’ means to secure their rights. A good example of this is protestors who are also more likely to vote than non-protestors. Taken together, these findings affirm both the way in which the racial and partisan legacy of the past is being undone by new institutions and practices, and suggest the complex intersection of these with networks of personal relations which characterise the local politics of most African cities. 相似文献
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How might an international plan for crustal-movement studies in Africa be implemented? This was the basic question underlying much of the discussion at the First International Symposium on Crustal Movements in Africa, convened in May 1981 in Addis Ababa at the United Nations Economic Commission for Africa. Three years later, in November/December 1984, the Second Symposium was held in Cairo, Egypt; and in April 1986, some outstanding questions were dealt with at the Third Symposium on Geodesy in Africa held in Yamoussoukro, Ivory Coast, and at the International Symposium on Global Changes in Africa during the Quaternary, held in Dakar, Senegal.The present state and possible development of recent crustal movement studies in Africa are discussed. Finally, the cooperation of all scientists interested in such studies is solicited. 相似文献
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