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Isotopic ratios of Sr and Nd can be used as very precise tracers- in conjunction with mineralogical, geochemical tracers and climatic models-, to identify the origins of dust deposit and to quantify their fluxes, both today and throughout the last climatic cycles. This technique is useful for constraining aeolian transport and atmospheric circulation trajectories from desert sources and over the oceans. The present work concerns dust deposits surrounding the Saharan desert. On the Canary Islands, the African fraction of the dust deposits displays isotopic values which are typical of Moroccan origin. On the other hand, Tunisian loesses have been derived from the northern part of the Sahara. In this case, tracers are sensitive enough to distinguish between center Saharan shield origin, and peri-Saharan secondary sources, allowing us to distinguish between transport due to the Trade Winds, vs the Harmattan or "Mediterranean" wind regimes.