• Petrogenetic characterization of pegmatites and their host rocks in southern Akwanga, North-Central Basement Complex, Nigeria

    • Fulltext


        Click here to view fulltext PDF

      Permanent link:

    • Keywords


      Nigerian basement complex; southern Akwanga rare metal pegmatites; LCT and peraluminous; crystal fractionation; anataxis.

    • Abstract


      The pegmatites in southern Akwanga occur within the reactivated belt of the basement complex of Nigeria. The pegmatites consist of dominantly albite–muscovite pegmatites (rare-metal), southern parts of the map areas and biotite-microcline pegmatites (barren) central parts of the map. The pegmatites intruded gneiss-migmatitic complex consist of metasedimentry rocks; granitic gneisses and biotite gneisses and rarely meta-igneous, amphibolites. The rare metal pegmatites are composed of quartz, albite and muscovites and tourmaline. Garnets, ilmenites and minor tin–columbite–tantalite mineralization constitute accessory minerals in contrast to the biotite-microcline pegmatites. The host rocks are composed of quartz, plagioclase (An$_{5–21}$; albites–oligoclase), microcline and muscovite. Minor constituents include biotites, cordierites and hornblendes. Ilmenite occurs as opaques. The pegmatites and their host rocks are corundum and hypersthene normative, highly peraluminous, exhibiting similar geochemical signatures; however, the rare metal pegmatites are more fractionated than the host rocks and the biotite-microcline pegmatites. The rare metal pegmatites are relatively enriched in Rb, Li, Cs, B, Be, Nb and Ta, low in K/Rb and Al/Ga ratios than the biotite–microcline–pegmatites and their host rocks. The pegmatites are products of crustal anatexis of sedimentary origin. This indicates that the rare metal pegmatites are source rock controlled (product of post-collision activities) rather than fractional crystallization.


      $\bullet$ Rare metal pegmatites occur in Southern Akwanga, north central Nigeria

      $\bullet$ Highly peraluminous and LCT pegmatites

      $\bullet$ Sn–Nb–Ta mineralization potentials in the pegmatite

      $\bullet$ They are related to the migmatitic-gneiss complex by anatexis

    • Author Affiliations



      1. Department of Geology, Ebonyi State University, Abakaliki, Nigeria.
      2. Department of Geology, University of Nigeria, Nsukka, Enugu State, Nigeria.
    • Dates

  • Journal of Earth System Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2022-2023 Indian Academy of Sciences, Bengaluru.