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.

Petrogenetic links between rare metal-bearing pegmatites and TTG gneisses in the West African Craton: The Mangodara district of SW Burkina Faso

“…Gneiss and granitoids correspond to calc-alkalic granitoids with metaluminous composition (Fig. 18b), like most Eburnean granitoids (Castaing et al, 2003;Ilboudo et al, 2020). The granodioritic gneiss, the hornblende-biotite granodiorite with mica-rich enclaves and the GG-granitoids have chemical affinities typical of a calc-alkaline K-rich series, whereas the tonalitic-trondhjemitic gneiss, the trondhjemite, and the two-mica tonalite have the chemical affinity of a Na-rich series (Fig.…”

“…Enrichment in LREE relative to HREE, and negative Nb and Ti anomalies are characteristic of tholeiitic to calc-alkaline basalts and andesites such as the ones exposed in the Houndé and Banfora greenstone belts (Fig. 17a) (Baratoux et al, 2011;Ilboudo et al, 2020), but also in many areas of the Baoule-Mossi domain (Béziat et al, 2000;Ilboudo et al, 2017a;Lompo, 2009;Lüdtke et al, 1998;Pouclet et al, 1996).…”

Geochemical Mobility Associated to Gold and Base Metal Occurrences of Mangodara Sector, in Southern Burkina Faso, Banfora Greenstone Belts (West African Craton)

“…The eastern part of the Banfora belt consists of interlayered units of basalts, andesites, volcano-sediments and rhyolites, 2 to 4 km thick, while the western part is composed solely of volcano-sediments according to [36]. The global stratigraphy of the belt proposed by these authors and revised by Ilboudo [43] suggests, from bottom to top: 1) deposition of ultramafic rock; 2) mafic volcanic; 3) subsequent deposition of lava flow and projection (pyroclastite and lapilli tuff); 4) deposition of siliceous rock (exhalite); 5) emplacement of pelitic and turbiditic sediments; 6) emplacement of the pre-collision eastern granite and 7) emplacement of the post-collision western granite. The volcanic activity that prevailed in West Burkina Faso took place between 2190 Ma and 2160 Ma (Eoeburnean) according to [36] and presents a juvenile character with regard to ԑHf (~0 to +8) [38].…”

“…(a) geological map of the Leo/Man shield and the most important gold deposits across the WAC (Modified from [17]); (b) simplified geological map of Banfora green belt (modified from [34]) and location of the studied area. from metabasalts to metarhyolites and metasedimentary rocks including quartzites and metapelites [23] [36] [42] [43]. Specifically, the Banfora belt that extends over 160 km long and 35 km wide [43] in Burkina Faso lays up to Côte d'Ivoire; and is intersected by the Bobo-Dioulasso high strain corridor representing the continuity of the major Greenville-Ferkéssédougou-Bobo-Dioulasso shear zone (Figure 1(b)).…”

“…from metabasalts to metarhyolites and metasedimentary rocks including quartzites and metapelites [23] [36] [42] [43]. Specifically, the Banfora belt that extends over 160 km long and 35 km wide [43] in Burkina Faso lays up to Côte d'Ivoire; and is intersected by the Bobo-Dioulasso high strain corridor representing the continuity of the major Greenville-Ferkéssédougou-Bobo-Dioulasso shear zone (Figure 1(b)). The eastern part of the Banfora belt consists of interlayered units of basalts, andesites, volcano-sediments and rhyolites, 2 to 4 km thick, while the western part is composed solely of volcano-sediments according to [36].…”