Advanced search

Petrographic and mineralogical characterisation of fractionated pegmatites culminating in the Nb-Ta-Sn pegmatites of the Gatumba area (western Rwanda)

(2013) GEOLOGICA BELGICA. 16(1-2). p.105-117
Author
Organization
Abstract
The Karagwe-Ankole belt in Central Africa hosts numerous rare-metal pegmatites and Sn-W mineralised quartz veins, which are related to the granite generation that formed at 986 +/- 10 Ma, i.e. the G4-granites in Rwanda. This early Neoproterozoic granite generation features in the Gatumba area (western Rwanda) a linkage with a zoned cluster of barren and Nb-Ta-Sn mineralised pegmatites. The most distal pegmatite bodies in this area suffered from intense alkali metasomatism, i.e. widespread growth of albite and white mica. A petrographic and geochemical study has been carried out on the pegmatite bodies in order to determine the petrogenetic evolution of the pegmatite zonation. The compositional variation of schorl and elbaite, sampled along the regional zonation sequence, implies that the zonation can be expressed by 4 zones: a biotite, a two-mica, a muscovite and a mineralised pegmatite zone. Alkali element variations and enrichments in muscovite and K-feldspar along the zonation sequence indicate that the origin and the formation of the different pegmatite zones can be explained by a single path of fractional crystallisation. This substantial chemical differentiation accompanies in the Gatumba pegmatite field the evolution from the G4-granite generation to common pegmatites and eventually rare-element pegmatites.
Keywords
Karagwe-Ankole belt, G4-granites, regional pegmatite zonation, LCT-family, mineral geochemistry, fractional crystallisation, alkali metals, ELEMENT GRANITIC PEGMATITES, CENTRAL-AFRICA, TRACE-ELEMENTS, TUNGSTEN MINERALIZATION, INTERNAL EVOLUTION, ALKALI FELDSPAR, KIBARA BELT, NOVA-SCOTIA, TOURMALINE, PROVINCE

Citation

Please use this url to cite or link to this publication:

Chicago
Hulsbosch, Niels, Jan Hertogen, Stijn Dewaele, Luc André, and Philippe Muchez. 2013. “Petrographic and Mineralogical Characterisation of Fractionated Pegmatites Culminating in the Nb-Ta-Sn Pegmatites of the Gatumba Area (western Rwanda).” Geologica Belgica 16 (1-2): 105–117.
APA
Hulsbosch, N., Hertogen, J., Dewaele, S., André, L., & Muchez, P. (2013). Petrographic and mineralogical characterisation of fractionated pegmatites culminating in the Nb-Ta-Sn pegmatites of the Gatumba area (western Rwanda). GEOLOGICA BELGICA, 16(1-2), 105–117.
Vancouver
1.
Hulsbosch N, Hertogen J, Dewaele S, André L, Muchez P. Petrographic and mineralogical characterisation of fractionated pegmatites culminating in the Nb-Ta-Sn pegmatites of the Gatumba area (western Rwanda). GEOLOGICA BELGICA. 2013;16(1-2):105–17.
MLA
Hulsbosch, Niels, Jan Hertogen, Stijn Dewaele, et al. “Petrographic and Mineralogical Characterisation of Fractionated Pegmatites Culminating in the Nb-Ta-Sn Pegmatites of the Gatumba Area (western Rwanda).” GEOLOGICA BELGICA 16.1-2 (2013): 105–117. Print.
@article{8550115,
  abstract     = {The Karagwe-Ankole belt in Central Africa hosts numerous rare-metal pegmatites and Sn-W mineralised quartz veins, which are related to the granite generation that formed at 986 +/- 10 Ma, i.e. the G4-granites in Rwanda. This early Neoproterozoic granite generation features in the Gatumba area (western Rwanda) a linkage with a zoned cluster of barren and Nb-Ta-Sn mineralised pegmatites. The most distal pegmatite bodies in this area suffered from intense alkali metasomatism, i.e. widespread growth of albite and white mica. A petrographic and geochemical study has been carried out on the pegmatite bodies in order to determine the petrogenetic evolution of the pegmatite zonation. The compositional variation of schorl and elbaite, sampled along the regional zonation sequence, implies that the zonation can be expressed by 4 zones: a biotite, a two-mica, a muscovite and a mineralised pegmatite zone. Alkali element variations and enrichments in muscovite and K-feldspar along the zonation sequence indicate that the origin and the formation of the different pegmatite zones can be explained by a single path of fractional crystallisation. This substantial chemical differentiation accompanies in the Gatumba pegmatite field the evolution from the G4-granite generation to common pegmatites and eventually rare-element pegmatites.},
  author       = {Hulsbosch, Niels and Hertogen, Jan and Dewaele, Stijn and Andr{\'e}, Luc and Muchez, Philippe},
  issn         = {1374-8505},
  journal      = {GEOLOGICA BELGICA},
  language     = {eng},
  number       = {1-2},
  pages        = {105--117},
  title        = {Petrographic and mineralogical characterisation of fractionated pegmatites culminating in the Nb-Ta-Sn pegmatites of the Gatumba area (western Rwanda)},
  volume       = {16},
  year         = {2013},
}

Web of Science
Times cited: