Basic magma tectonics contrasted to folding of basic rocks

In the Precambrian gneisses of SE Norway, several generations of amphibolitised basic dykes/sills occur. While prekinematically emplaced dykes and sills show normal (but complex) fold structures, other metabasic intrusions have imposed a deformation on to the host rock. Apparent fold structures which have developed due to fabric control exerted by the host rocks, are recorded from late kinematic intrusions. Attention is drawn to the problem of distinguishing primary intrusive structures from simple and multiple fold-structures.

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Zusammenfassung In die präkambrischen Gneise Südost-Norwegens sind mehrere Generationen amphibolisierter basischer Gänge bzw. Sills eingedrungen. Während präkinematisch angelegte Gänge und Sills normale (aber komplexe) Faltenstrukturen zeigen, haben andere metabasische Intrusionen das Nebengestein beansprucht. Deutliche Faltenstrukturen, die sich in der Gefügekontrolle des Nebengesteins manifestieren, werden von spätkinematischen Intrusionen berichtet. Besondere Beachtung wird der Unterscheidung primärer Intrusivstrukturen von einfachen und multiplen Faltenstrukturen geschenkt.

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Résumé Dans le SE de la Norvège, les gneiss Précambriens contiennent plusieurs générations de dykes et sills basiques amphibolitisés. Les dykes et sills prétectoniques montrent des structures de plissement, normales quoique compliquées. Par contre, les autres intrusions basiques ont déformé les roches encaissantes. Localement, des intrusions tardi-tectoniques présentent des plissements apparents controlés et provoqués par la structure de la roche encaissante. L'attention est portée sur le problème de distinction entre des structures intrusives primaires et des structures de plissement, simples et multiples.

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Contemporaneous development of mullions and hornblende lineations in divergent directions

A mullion structure is described from a several meter thick amphibolite from the Precambrian bedrock of south-eastern Norway. The mullion axes deviate about 60–70⁰ from the fold axis defined in the amphibolite by the constructed intersection of foliation planes. The fold axis is also reflected in the lineated hornblende grains. The orientation of the mullion axes is parallel to the trace of the amphibolite foliation on the mullioned surface. It is concluded that the mullions were formed on a discordant surface (probably a fracture surface) in responce to movement along the intersecting foliation planes at the same time as the hornblende lineation was developed.

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Zusammenfassung Aus dem südostnorwegischen präkambrischen Grundgebirge wird aus einem mehrere Meter mächtigen verfalteten Amphibolit eine Mullion-Struktur beschrieben. Die Achsen der Mullions weichen 60–70⁰ von der Faltenachse ab, welche aufgrund der Biotitfoliationen im Amphibolit konstruiert werden konnte. Diese Faltenachse wird auch von den linearen Hornblenden nachgezeichnet. Es wird angenommen, daß sich die Mullions auf einer diskordanten Fläche (wahrscheinlich einer Bruchfläche) gebildet haben. Auf dieser Fläche verlaufen die Mullion-Achsen parallel der Spur der Amphibolit-Foliation. Die Mullions entstanden gleichzeitig mit den linearen Hornblenden infolge einer Bewegung entlang der sich schneidenden Foliationsebenen.

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Résumé Une structure en «mullion» a été étudiée dans des amphibolites, d'âge Précambrien, en Norvège. Les mullions proviennent d'une couche discordante, qui a été déformée avec les amphibolites. On observe que les axes des mullions font une angle de 60 à 70 degré avec la linéation (prismes de hornblende) qui est parallèle aux axes des plis; les axes des mullions et la linéation sont situés dans le plan de la foliation des amphibolites.

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Climate Change Impact on Snow Coverage, Evaporation and River Discharge in the Sub-Arctic Tana Basin, Northern Fennoscandia

Arctic environments are generally believed to be highly sensitive to human-induced climatic change. In this paper, we explore the impacts on the hydrological system of the sub-arctic Tana Basin in Northernmost Finland and Norway. In contrast with previous studies, attention is not only given to river discharge, but also to the spatial patterns in snow coverage and evapotranspiration. We used a distributed water balance model that was coupled to a regional climate model in order to calculate a scenario of climate change by the end of this century. Three different model experiments were performed, adopting different approaches to using the climate model output in the hydrological model runs. The results were largely consistent, indicating a much shorter snow season and, accordingly, decreased sublimation, an increase in evapotranspiration, and a shift in the annual runoff peak. As the snow-free season is extended, the amount of solar radiation that is received during this period increases significantly. The results also show important local differences in the hydrological response to climate change. For example, in the scenario runs, the snow season was more than 30 days shorter at higher elevations, but in some of the river valleys, this was up to 70 days.     

Future extreme events in European climate: an exploration of regional climate model projections

This paper compares how well satellite versus weather station measurements of climate predict agricultural performance in Brazil, India, and the United States. Although weather stations give accurate measures of ground conditions, they entail sporadic observations that require interpolation where observations are missing. In contrast, satellites have trouble measuring some ground phenomenon such as precipitation but they provide complete spatial coverage of various parameters over a landscape. The satellite temperature measurements slightly outperform the interpolated ground station data but the precipitation ground measurements generally outperform the satellite surface wetness index. In India, the surface wetness index outperforms station precipitation but this may be reflecting irrigation, not climate. The results suggest that satellites provide promising measures of temperature but that ground station data may still be preferred for measuring precipitation in rural settings.     

All about water and land? Resource-related conflicts in East and West Africa revisited

Recent years have seen an upsurge in the numbers of studies investigating the potential link between climate variability and conflict—and particularly so quantitative studies of this relationship—without reaching any consensus on causal pathways or main findings. This study sets out to explore what the main causes of conflict between resource-user groups in arid and semi-arid areas in Sub-Saharan Africa are, with a particular focus on renewable-resource scarcity. We conduct a comparative analysis of eleven high-quality case studies of the escalation into violence of disputes between pastoralists and farmers or pastoralists in the Western Sahel and East Africa. This enables us to identify the mechanisms underpinning the actors’ motivations. Our analysis shows that the nature of these conflicts is complex. They cannot be reduced to a stimulus (resource scarcity)–response (violence) relationship. We find that drought is a contributing factor in four of the conflicts, and that a poor rainy season plays a role in a fifth one. However, resource scarcity is never the most important cause and it does not explain well the differences in conflict intensity. The most important contributor to explaining different levels of intensity is when local autochthonous and exclusionary claims are coupled with national-level political processes.