A morphologically distinct intrusive massif emerges from sedimentary Mesozoic/Tertiary cover in Eastern Socotra forming the high Haggier Mts. It is mostly composed of peralkaline a nd hypersolvus granite partly accompanied by gabbroic rocks. Amphibole, the sole mafic mineral of th e granite, shows predominately the arfvedsonite composition, while riebeckite, for which Socotra is reported in most manuals of mineralogy as the "locus typicus", occurs subordinately only. Either Paleozoic or Tertiary age has been assumed for this massif for a long time. In the last decade, however, K/Ar datings have been published clearly showing Precambrian (Ne oproterozoic) age. The present authors confirm with somewhat modified results this statement by five new radiometric measurements of monomineral amphibole fractions yiel ding values of 687 to 741 Ma for granites and 762 Ma for gabbroic rocks. The massif represents an isolated segment of numerous late postorogenic Pan-African A-granite bodies piercing the Nubian-Arabian Shield an d is explained as the result of partial melting of Pan-African calc-alkaline shield rocks in the closing stage of the orogeny., Ferry Fediuk and Kadosa Balogh., and Obsahuje bibliografické odkazy
This paper deals with the causes of the Arab Spring in Yemen. It analyses political causes such as the system of political patronage and both the internal and external conflicts, which have weakened the state at multiple levels. It also discusses the social and economic causes, such as poverty, unemployment and the problems of oil, qat and water. This combination of political and socioeconomic factors, fuelled by the protests in Tunisia and Egypt, created a revolution, which led to the overthrow of the president, Ali Abdullah Saleh, who had ruled Yemen for 33 years., Veronika Kramáreková., and Obsahuje bibliografii