Intrusive rocks and tectono-metamorphic evolution of the Mako Paleoproterozoic belt (Eastern Senegal, West Africa)

Structural Evolution of a Precambrian Segment: Example of the Paleoproterozoic Formations of the Mako Belt (Eastern Senegal, West Africa)

“…The D2 phase was interpreted as transcurrent deformation along a network of ductile shear zones (Milesi et al, [12], Ledru et al, [15]) and corresponds to transpression accommodating the emplacement of the Laminia Kaourou Plutonic complex (LKPC) (Gueye,[16]). It has been long postulated that the elongated shape of most of the intrusions was due to syntectonic emplacement in relation with the activity of the shear zones (Pons [17], Gueye et al [18]). Two geodynamic environments for the Birimiantholeiitic rocks have been proposed, either an intra-oceanic islandarc setting (Zonou [19]; Dia [2]; Sylvester and Attoh [20], Ama-Salah et al [21], Pawlig et al [7]) or an oceanic plateau setting (Abouchami et al [3]; Boher et al [4]; Pouclet et al [22]).…”

“…They separate blocks with distinct structural-metamorphic histories. Many authors have suggested a genetic relationship between faults (or shear zones) and magmatism (Gueye et al [18], Pons [17]). The Mako Belt displays a prominent N-S and NE-SW structural trend resulting from regional NE to N-trending folds with axial planar schistosity that is characteristic of the belt.…”

“…The volcanic, volcanoclastic sequence is intruded by various dykes, sills of trondhjemites and metagabbros. Metamorphic conditions grade from greenschistfacies in the southern part of the domain to amphibolite and granulite facies and local anatexis in the Sandikounda area (Gueye et al, [18]). …”

Sr and Nd isotopic geochemistry of the early ultramafic–mafic rocks of the Mako bimodal volcanic belt of the Kedougou–Kenieba inlier (Senegal)

“…The Dialle-Dalema supergroups represent sedimentary basins with mainly detrital sedimentary rocks and limestones successions interbedded with calc−alkaline volcanic rocks (Ndiaye et al 1997). The regional crustal shear zone (Main Transcurrent Shear Zone) with NE−SW trend, follows the lithological contact between the Mako and the Dialé−Daléma supergroups Guéye et al 2008).…”

“…Recent studies indicates that the Mako bimodal volcanic belt is intruded by four generations of granitoids which express a multiphase evolutionary history spreading between 2200 to 2080 Ma for the edification of the Paleoproterozoic continental crust (Guéye et al 2008). The first generation of granitoids with TTG affinities dated between 2213 to 2198 Ma, would be derived from the partial melting of basalts (Bassot and Caen Vachette, 1984;Dia et al 1997;Pawlig et al 2006;Guéye et al 2008).…”