Geochemistry and geodynamic constraint of volcanic and plutonic magmatism within the Banfora Belt (Burkina-Faso, West-Africa): contribution to Mineral Exploration
【Abstract】
Predominant volcano-plutonic (mafic-felsic) activity is expressed in the eastern Banfora Belt (BB). Geochemical signature shows different geodynamic settings: i) mafic rocks are tholeiitic, sub-alkaline and show high-Mg tendency, whereas pyroxenolite (MgO ∼ 15.4 wt%) has komatiite affinity; ii) felsic volcanic rocks are sub-alkaline; iii) granitoids surrounding the BB are alkaline to calc-alkaline, high K, peraluminous to metaluminous. Geochemistry of mafic volcanic rocks shows an unusual an evolution from Middle Oceanic Ridge Basalt (MORB) to Arc-related. The Western Granite (WG) and Eastern Granites (EGs) emplaced by fractional crystallization and partial melting respectively, but sourced from igneous protolith (I-type magma) in volcanic arc setting (VAG). The Sodingue granite emplaced by fractional crystallization from A-type magma in “within plate setting”. Two-micas S-type granites located at the central portion of the belt and relate to syn-collisional fractional crystallization. The paper highlights the complexity of magma process throughout a diversity of sources, geochemical pattern and tectonic setting. An emphasis on the komatiite affinity of mafic magma is a challenge for related commodities, such as copper and gold resources.
【Author】
Hermann Ilboudo, Sâga Sawadogo, G. Hubert Zongo, Seta Naba, Urbain Wenmenga, Martin Lompo
【Journal】
Geological Society London Special Publications(IF：1) Time：2020-09-29
