A Syntectonic Alkaline Massif in Burundi: Geology, Fluid-Rock Interaction and Element (REE, HFSE) Mobility

International audienceAlkaline massifs worldwide are generally atectonic. In Burundi, during the break-up of Rodinia, 700 Ma ago, the Upper Ruvubu Alkaline Plutonic Complex emplaced syntectonically. Large shear zones affecting the intrusion accommodated a regional NE-SW shortening in the regional extensional setting associated with Rodinia breakup. Magmatic dykes and magmato-hydrothermal mineralized veins strike NE-SW and have accommodated NW-SE stretching. C and O isotope characterization of the central Matongo carbonatite body attests for superimposed hydrothermal alterations, which induced REE and HFSE mobilizations on various scales