caa a22 4500 606149929 CHVBK 20210128100536.0 cr unu---uuuuu 210128e20150701xx s 000 0 eng 10.1007/s00531-015-1157-3 doi (NATIONALLICENCE)springer-10.1007/s00531-015-1157-3 Mineralogy and geochemistry of Neoproterozoic siliceous manganese formations from Ntui-Betamba (Cameroon Pan-African Fold Belt): implications for mineral exploration [Elektronische Daten] [Ngnotue Timoleon, Ganno Sylvestre, Gus Kouankap Nono, Nzenti Paul] The siliceous manganese formations from Ntui-Betamba area have been studied with the aim to constrain their mineralogy, geochemistry, and genesis. Neoproterozoic manganese-bearing rocks at Ntui-Betamba include garnet-galaxite-bearing quartzite and galaxite-bearing quartzite that—besides a characteristic quartz, spessartine-garnet, and galaxite (MnAl2O4) assemblage—comprises also graphite and rutile. Galaxite crystals show chemical zoning from core to rim due to the change in composition from galaxite to cryptomelane. Bulk rock geochemistry reveals that the studied rocks are characterized by high SiO2 content (52.83wt%). They are enriched in Fe2O3 and Al2O3 and display Mn/Fe ratio of 1.2. MnO concentrations are high in galaxite-bearing quartzite (16wt%), and moderate (8.03wt%) in garnet-galaxite-bearing quartzite. The transition trace metal (Co, Cu, and Ni) contents are lower, with Co and Cu markedly depleted relative to Ni, and variable contents of Zn. The REE pattern of garnet-galaxite-bearing quartzite shows Ce-positive anomaly similar to the hydrogenous sediment, but differs from the later with strong Eu-negative anomaly and the lack of weak positive anomaly in Yb, whereas the galaxite-bearing quartzite is characterized by the lack of Ce anomaly and the weak Eu-negative anomaly. Both rocks show HREE content close to that of hydrothermal sediment and exhibit flat HREE trend. The high contents of silica, iron, and aluminum, together with the Co/Zn ratios (~0.3) and the contrasting behavior of REE, suggest that the studied manganese-bearing rocks are of sedimentary origin probably derived from a mixed hydrothermal-hydrogenous source. The high content of Mn-bearing minerals in these rocks represents indicators of concealed or buried mineralization and could be used as exploration guide. Springer-Verlag Berlin Heidelberg, 2015 Manganese-bearing rocks nationallicence Galaxite nationallicence Spessartine-garnet nationallicence Hydrothermal-hydrogenous source nationallicence Ntui-Betamba nationallicence Cameroon nationallicence Timoleon Ngnotue Department of Geology, University of Dschang, P.O. Box. 67, Dschang, Cameroon aut Sylvestre Ganno Department of Earth Sciences, University of Yaoundé I, P.O. Box. 812, Yaoundé, Cameroon aut Kouankap Nono Gus Department of Earth Sciences, University of Yaoundé I, P.O. Box. 812, Yaoundé, Cameroon aut Paul Nzenti Department of Earth Sciences, University of Yaoundé I, P.O. Box. 812, Yaoundé, Cameroon aut International Journal of Earth Sciences Springer Berlin Heidelberg 104/5(2015-07-01), 1123-1138 1437-3254 104:5<1123 2015 104 531 https://doi.org/10.1007/s00531-015-1157-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00531-015-1157-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Timoleon Ngnotue Department of Geology, University of Dschang, P.O. Box. 67, Dschang, Cameroon aut NATIONALLICENCE 700 1- Sylvestre Ganno Department of Earth Sciences, University of Yaoundé I, P.O. Box. 812, Yaoundé, Cameroon aut NATIONALLICENCE 700 1- Kouankap Nono Gus Department of Earth Sciences, University of Yaoundé I, P.O. Box. 812, Yaoundé, Cameroon aut NATIONALLICENCE 700 1- Paul Nzenti Department of Earth Sciences, University of Yaoundé I, P.O. Box. 812, Yaoundé, Cameroon aut NATIONALLICENCE 773 0- International Journal of Earth Sciences Springer Berlin Heidelberg 104/5(2015-07-01), 1123-1138 1437-3254 104:5<1123 2015 104 531