The Logoualé Band: A large Archean crustal block in the Kenema-Man domain (Man-Leo rise, West African Craton) remobilized during Eburnean orogeny (2.05 Ga)

Abstract The Archean domain of the Man Rise was strongly remobilized during Eburnean coincidentally with the genesis of the Baoule-Mossi domain (Birimian). This remobilization has allowed the recycling of Leonian and Liberian formations to generate a large gneissic crust, represented by the Logouale Band. Zircons dates by laser ablation (LA-ICP-MS) of two samples of biotite-bearing pink gneisses of the Logouale Band yielded ages of 2709 ± 15 and 2804 ± 11 Ma, confirming the Archean age of the Logouale Band formations. The Eburnean tectono-metamorphic event in the Logouale Band has totally reset both U-Th-Pb chronometer with an average age at 2050 ± 16 Ma in recrystallized zones of monazites, and Sm-Nd chronometer of garnets with an age at 2053 ± 15 Ma. Non-recrystallized zones of monazites give an average age at 2712 ± 16 Ma. We propose that the Logouale Band rocks were originally sediments deposited in some protocratonic rift-type basins. During Eburnean, these sediments were buried, underwent high-grade metamorphism and exhumed in a tectonic context dominated by transcurrent motion. The structural setting of banded iron formations (iron deposits), which are abundant in the Logouale Band, would date back to the Eburnean.