Searching for core area growth

Until recently the world economy was focused on four core areas: in western Europe, North America, the Soviet Union, and Japan. Beyond them was the periphery. The economic growth of the periphery depended on core-periphery trade. Since the existing core areas were too few to absorb the periphery's potential production, much of the periphery was producing below capacity. Currently more core areas are coming into existence in Brazil, South Korea, and India. They promote economic development by enlarging the market for peripheral products, drawing resources from the remaining periphery, and providing competition to existing core areas. Latent potentials for core area growth exist in the Near East and southern Africa, but their realization presumes political settlements. The west European core area has expanded onto the Iberian Peninsula and may expand soon beyond the erstwhile Iron Curtain.     

The role of rural-rural migration as a survival strategy in the Sahelian zone of the Sudan —

Taking the example of Burush, N Darfur, Sudan, the authors analyse the role of migration as a survival strategy in the desertification-stricken Sahelian zone. It is being argued that the rual-rual migration plays a greater role than the rual-urban migration among the Berti ethnic group of northern Darfur. Their high mobility within their own area is part of their traditional economic pattern for coping with aridity and high rainfall variability     

Pyroxene chemistry and evolution of alkali basaltic rocks from Burgenland and Styria,Austria

Summary The mineral chemistry of several Pliocene alkali basaltic rocks from Burgenland and Styria (Eastern Austria) have been investigated in order to determine the evolution path of the basalt magmas prior to eruption. With their wide range of substitutions, clinopyroxenes provide the best records of the evolution history of rocks. Pyroxene phenocrysts of the investigated basalts show both concentric and sector zoning. The investigation of sector zoned crystals shows, that not only Ti, Al and Fe contents are different in different sectors but there can be significant differences also in their Cr content. This fact apparently suggests that the distribution of Cr between clinopyroxene and melt could be influenced by crystallization kinetics.The depth of crystallization and differentiation of the basalts can be estimated from Ti and Al contents of clinopyroxene phenocrysts. From a combination of data on clinopyroxene composition, compatible trace element contents and mg-values of the rocks, it is concluded, that the alkali basalts of Pauliberg and Steinberg underwent slight olivine and clinopyroxene fractionation in shallow magma chambers prior to eruption, while the nephelinite of Stradnerkogel evolved mainly through clinopyroxene fractionation under high pressure conditions, probably in the upper mantle.

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Chemie der Pyroxene und Entwicklung von Alkalibasalten aus dem Burgenland und der Steiermark, Österreich

Zusammenfassung Einige pliozäne alkalibasaltische Gesteine aus dem Burgenland und der Steiermark wurden mineral-chemisch untersucht, um Aufschluß über ihre Evolution vor der Eruption zu erhalten. Klinopyroxene mit ihren vielfältigen Subtitutionsmöglichkeiten erlauben am besten eine Abschätzung der Evolution der Basalte. Pyroxen-Einsprenglinge der Basalte zeigen sowohl konzentrischen als auch sektoralen Zonarbau. Die von uns untersuchten Einsprenglinge zeigen in den verschiedenen Sektoren nicht nur unterschiedliche Gehalte an Ti, Al und Fe, sondern vielfach auch unterschiedliche Cr-Gehalte. Dies macht es wahrscheinlich, daß die Verteilung von Cr zwischen Klinopyroxen und Schmelze von der Kristallisations-Kinetik beeinflußt wird.Die Tiefe in der die Basalte kristallisierten und differenzierten kann von den Ti- und Al-Gehalten der Klinopyroxen- Einsprenglinge abgeschätzt werden. Die Zusammensetzung der Klinopyroxene im Verein mit den Gehalten an kompatiblen Spurenelementen und denmg-Werten der Gesteine erlauben den Schluß, daß die Alkalibasalte von Pauliberg und Steinberg vor ihrer Eruption eine geringfügige Olivinund Klinopyroxen-Fraktionierung in einer seichten Magmakammer erlebten. Der Nephelinit vorn Stradnerkogel hingegen erfuhr hauptsächlich eine Klinopyroxen Fraktionierung unter Hochdruck-Bedingungen, möglicherweise im oberen Erdmantel.

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With 8 Figures     

Desertification,famine, and the 1988 rainfall —

The 1988 good rainy season in the Sudan raised the hopes that desertification/land degradation and shortage of food so markedly observed in Western Sudan have been elevated. This was particularly so as large quantities of grains were produced in the mechanized rain-fed agricultural schemes in the clay plains of Eastern Sudan. But the field work carried by the author in the Umm Ruwaba district of Kordofan region in July/August 1989 shows that, although there has been some improvement in the crop production situation, desertification/land degradation and shortage of food produced locally are still prevailing in the district. The people are still living below the poverty line, but they are able to cope because of remittances from members of the families working abroad and because of donations of food by some world organizations.     

Stress-strain fields at the tunnelling face—Three-dimensional analysis for two-dimensional technical approach

Summary For tunnelling in rock, the original stress field in the ground is changed considerably before a first lining is participating in stabilizing the opening. Depending on this stress release at the tunnel face, only a small portion of the primary stresses is acting on the lining. Only a three-dimensional approach is able to determine the stresses and the deformations of the ground and the lining realistically. The paper presents some results of elastic three-dimensional finite-element-analyses in consecutive steps of the sectional excavation of circular and non-circular tunnels. From these results an equivalent two-dimensional approach is derived for technical applications, given in diagrams.     

7th World Congress on water resources Rabat,Morocco, 13–18 May, 1991

Submitted to United Nations Environment Programme Nairobi, Kenya by International Water Resources Association.