抄録
The major and trace element (including rare earth element) compositions of 17 quartzite and 4 metapelite samples from the Upper Proterozoic Togo Formation, southeast Ghana, have been investigated to determine their provenance and tectonic setting. The major and trace element compositions of the quartzites and metapelites are comparable to those of average Proterozoic sandstones and Proterozoic shale, respectively, but with slight depletion in ferromagnesian elements such as Mg, Fe, Cr, Ni, Co and V. The dominance of SiO2, generally low Fe2O3 and MgO concentrations, and REE patterns with negative Eu anomalies suggest that the Togo Formation is dominated by mature, cratonic detritus deposited on a passive margin. The granitoids and felsic gneisses of the Paleoproterozoic Birimian and Dahomeyan Formations appear the most likely source rocks. These results, therefore, support earlier studies that infer passive margin setting for the eastern margin of the West African Craton prior to the Pan-African orogeny.
