New Constraints from Pb-Evaporation Zircon Ages of the Méiganga Amphibole-Biotite Gneiss, Central Cameroon, on Proterozoic Crustal Evolution

Abstract

The amphibole biotite gneiss (ABGn) in the Méiganga area forms part of a meta volcano-sedimentary sequence of the Adamawa Yade domain (AYD), Central African Fold Belt (CAFB). This sequence shows affinity with immature sediments (greywackes, arkoses) with intercalation of mafic lavas or tuffs. New 207 Pb/ 206 Pb zircon evaporation ages for two ABGn samples range from 1887 -2339 Ma and from 675 -889 Ma, respectively. These ages and evidence from internal zircon structures indicate that igneous rocks of Archean to Paleoproterozoic and of early Neoproterozoic age contributed to the detritus of the sedimentary sequence. The deposition of detritus took place prior to 614 -619 Ma which represent the syntectonic emplacement of the Méiganga metadiorite. Leucogranites north to the Méiganga area were generated by melting of crust identical to that which provided the source of the ABGn. The metasedimentary sequence investigated in this study is similar to that of the southern part of the AYD and in the Borborema Province, NE Brazil. The tectonic and geochronologic characteristics of the AYD in the Méiganga area support the idea that during the Proterozoic, Central Africa and NE Brazil were part of the same continental landmass.

Lu-Hf Isotopic Data of the Mbé-Sassa-Mbersi Tonalite (Central Cameroon Domain): Indicator of ca. 1.0 Ga Juvenile Tonian Magmatism in the Region

“…This magmatism which is materialized in the outcrops by volcano-sedimentary formations associated with meta-mafic and felsic volcanic and plutonic rocks, orthogneisses and dolerite dykes show continental tholeiite and alkaline signature (Souza & Moura 1995;Vicat et al, 2001;Neves, 2003;Guimarães et al, 2012;Viana & Battilani 2014). In the Central Cameroon Domain in Central African Orogenic Belt (Figure 2(a) and Figure 2(b)), the tonian ages are mentioned in the biotite-muscovite granitoids (~926 Ma) and amphibole-biotite gneiss (~889 Ma) respectively in the Ngaoundere cliff and Meiganga area (Tchameni et al, 2006;Ganwa et al, 2011). But these ages have been interpreted as inherited and of no geological significance, probably due to the lack of more detailed studies.…”

Hydrogeophysical Investigation for Groundwater Resources from Electrical Resistivity Tomography and Self-Potential Data in the Méiganga Area, Adamawa, Cameroon

“…Several works have been made in the Méiganga area and its surroundings for the geological knowledge of the area [5,[9][10][11][12][13]. These studies revealed that the geological formations of the Méiganga area and its environs are part of the central Panafrican belt of Cameroon, which is denominated has the Adamawa Yadé domain (AYD) ( Figure 2).…”

“…It is underlain by syntectonic, late-tectonic, and posttectonic granitoids [9,10] which intrude in older metamorphic rocks. The granitoids present in the study area include biotite-muscovite granite and pyroxene amphibole-biotite granite [12,13]. The metamorphic host rocks consist of 2.1Ga metasediments (metamorphized conglomerates and clay sandstones) and orthogneisses, which were reworked during the Panafrican orogeny [11].…”