Abstract
The Archean domain of the Man Rise was strongly remobilized during Eburnean coincidentally with the genesis of the Baoulé-Mossi domain (Birimian). This remobilization has allowed the recycling of Leonian and Liberian formations to generate a large gneissic crust, represented by the Logoualé Band. Zircons dates by laser ablation (LA-ICP-MS) of two samples of biotite-bearing pink gneisses of the Logoualé Band yielded ages of 2709 ± 15 and 2804 ± 11 Ma, confirming the Archean age of the Logoualé Band formations. The Eburnean tectono-metamorphic event in the Logoualé 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 Logoualé 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 Logoualé Band, would date back to the Eburnean.
Published Version
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