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388 - Revised Earth history favours the search for African gold
November 2011
Potential treasures lie concealed under the West African savannah in some of the Earth’s poorest countries. Extensive gold fields occur, over hundreds of kilometres, from Senegal to Niger. The rapid rise in precious metal prices over the past five years has prompted hugely intensified mineral exploration. Yet new veins must be found if this African gold rush is to continue.
A new discovery, published in Nature Geoscience , is now shaking up our understanding of the Earth and the prospects for exploration. The research team ( 4), led by an IRD geologist, used innovatory modelling software to take a fresh look at the origins of plate tectonics in the light of the geothermal history of the gold deposits in the West African gold fields. These investigations will lead to better ways of locating the emplacement of veins and their depth. This result is a fundamental one for the science which furthermore offers promising applications for West African countries.
Africa’s monsoon challenge
September 2009
The monsoon sets the pattern of life of 300 million West Africans. The intensity and duration of the rains it brings govern all crop cultivation and water resources – and hence food security. In a period of less than four months, from June to September, it brings the greater part of the rainfall for the whole year. However, it has lost its intensity over the past decades, plunging the Sahel into a succession of famines.
As part of the international programme AMMA1, IRD research scientists and their partners have been making long-term observations on this erratic monsoon system in order to predict the consequences. The observation system AMMA-CATCH (Couplage de l’Atmosphère Tropicale et du Cycle Hydrologique
), launched in 2002 to study the coupling between the tropical atmosphere and the hydrological cycle, has brought to the fore certain characteristics and paradoxes of the water cycle associated with the African monsoon: a significant change in the season cycle and a decrease in the number of substantial rainfall events, but an increase in surface runoff and flooding in a greener Sahel.
