Análise descritiva das unidades portadoras de mineralização tantalífera em pegmatitos do sul da Província Zambeziana (Moçambique)

Abstract

The differences between NYF and LCT pegmatite evolution and regional distribution in Zambézia Pegmatite Province are the main determinants of its tantalum potentiality. Alto Ligonha District in Central Zambézia holds important Ta resources in relation to LCT giant pegmatites, which have been mined for decades and are reasonably known. Minor attention was dedicated since now to the South District. Recent studies dedicated to this domain revealed several pegmatite fields with a great diversity of Ta mineralization: M´Luma – Nicula - low Ta NYF pegmatites, with high Sc, Y, Ti, R.E. and ixiolite-cheralite dominant ores; Rio Licungo - low Ta NYF and beryl pegmatites, with high Bi, W and struverite dominant ores; Rio Namivo - low to high Ta NYF to LCT pegmatites, beryl rich with petalite and spodumene as high temperature remnants and tantalite-tapiolite-microlite dominant ores. Regional distribution and paragenetic analysis of some key pegmatites suggest that South District reveals a more proximal and sub-autochthonous emplacement of the pegmatite bodies in tangential ruptures under the cover terrenes of Mamala to Morrua Formations, which undergone a different evolution since Pan-African event to uplifting an exhumation. In what concerns the strategic stage of exploration, such a pattern of emplacement and evolution, suggests the possibility of future detection of unknown high Ta pegmatites at the South District.