Origin and age of the polymetallic (Au-Cu-Pb) mineralisation in the Mesoproterozoic Mpanda Mineral Field of the Paleoproterozoic Ubendian Belt, SW Tanzania
Our geochemical-mineralogical study decodes the genesis of the polymetallic (Au-Cu-Pb) vein deposits in the Mesoproterozoic Mpanda Mineral Field (MMF), which is hosted in the Archean to Paleoproterozoic Katuma Block of the Ubendian Belt in Tanzania. The host rocks of the ore veins have been pervasiv...
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| Autores principales: | , , , , , , , |
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| Formato: | Article (Journal) |
| Lenguaje: | inglés |
| Publicado: |
August 2026
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| In: |
Journal of African earth sciences
Year: 2026, Volumen: 240, Pages: 1-21 |
| ISSN: | 1879-1956 |
| DOI: | 10.1016/j.jafrearsci.2026.106136 |
| Acceso en línea: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1016/j.jafrearsci.2026.106136 Verlag, lizenzpflichtig, Volltext: https://www.sciencedirect.com/science/article/pii/S1464343X26001457 
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| Notas de Autor: | Emmanuel O. Kazimoto, Mary C. Moshi, Obeid S. Lemna, Remigius L. Gama, Octavian Minja, Yusto Joseph, Miriam Christina Reiss, Volker Schenk |
| Sumario: | Our geochemical-mineralogical study decodes the genesis of the polymetallic (Au-Cu-Pb) vein deposits in the Mesoproterozoic Mpanda Mineral Field (MMF), which is hosted in the Archean to Paleoproterozoic Katuma Block of the Ubendian Belt in Tanzania. The host rocks of the ore veins have been pervasively altered by hydrothermal fluids resulting in greenschist-facies alteration halos, reaching several tens of metres into the granulite-facies country rocks. Fresh vein rocks display open-space filling textures including subhedral minerals, vugs and encrustations and are composed of coarse-grained quartz, K-feldspar, siderite, barite, galena, pyrite and chalcopyrite. Gold occurs in contact with pyrite and chalcopyrite, whereas chalcopyrite and galena is associated with secondary aikinite, wittichenite and emplectite. Secondary covellite and digenite replace chalcopyrite. Secondary hematite, quartz, azurite, malachite and copper silicate minerals represent weathering products. Lead isotope compositions of primary vein sulphides are thorogenic, pointing to an upper crustal source for the ore-forming fluids. In vein siderite, δ13C values range from −7.5 to −6.5 ‰ V-PDB and δ18O values from 7.3 to 9.5 ‰ V-SMOW, in agreement with metamorphic or magmatic rocks as sources for the ore-forming fluids. Isotopic fractionation between siderite and quartz of the veins points to high temperature hydrothermal conditions of 390 to 500 °C, in agreement with the greenschist-facies minerals formed in the alteration haloes of the veins. The hydrothermal alteration in the halos adjoining the ore veins has been dated directly with hydrothermally recrystallised monazite grains at ca. 1170 Ma. Petrological studies in the Wakole Block, which adjoins the Katuma Block with its MMF to the West, identified a high-grade Kibaran metamorphic event at ca. 1170 Ma that was induced by orogenic crustal thickening and occurred coeval with the hydrothermal alteration near the veins. Thus, we propose that during the Kibaran orogeny metamorphic dehydration occurred in a subducting metasedimentary Wakole wedge beneath the Katuma Block. The liberated fluids ascended through this overlying block, where the polymetallic veins of the MMF precipitated, mainly along NNW-SSE and E-W striking and NE-dipping Paleoproterozoic fault zones, which became reactivated at ca. 1170 Ma during the Mesoproterozoic Kibaran orogeny. |
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| Notas: | Gesehen am 18.06.2026 |
| Descripción Física: | Online Resource |
| ISSN: | 1879-1956 |
| DOI: | 10.1016/j.jafrearsci.2026.106136 |