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Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications

Received: 9 August 2022    Accepted: 25 August 2022    Published: 5 September 2022
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Abstract

The tectonic evolution and provenance of the sediments from the Yaoundé Group remain poorly understood and somewhat enigmatic although the information it has already provided. This work presents the results of integrated field mapping, petrography and whole-rock geochemical studies of less documented metasedimentary rocks cropping in the southwestern portion of the Yaoundé Group, with the aim to enhance the geological setting of this group. These metasedimentary rocks comprise garnet-bearing chlorite schists, garnet micaschists and kyanite-bearing garnet migmatites. Their mineral assemblages suggest prograde metamorphism, from greenschist to granulite through amphibolite facies. Whole-rock geochemical data reveals wide range of Fe2O3 + MgO + TiO2 contents, from 7.3 to 32.6 wt.%, due to the diversity of lithological units. High Ba (616.833 ppm), V (145.333 ppm) and Zr (227.591 ppm) values suggest continental crust source materials. The average ratios of Nb/Ta (15.25), Zr/Hf (36.52) and Y/Ho (27.41) are closer to those of the upper continental crust. The average Th/U ratio, above 4.0 in investigated metasedimentary rocks, indicates intense weathering in the source areas or sediment recycling. The protoliths of the rocks are post-Archean shales and greywackes deriving mostly from andesites and granodiorites, probably from of the Congo craton and/or the Adamawa-Yadé block. The prominent tholeiitic geochemical affinity of these rocks suggests their emplacement in an active margin context and/or oceanic island arc setting.

Published in Earth Sciences (Volume 11, Issue 5)
DOI 10.11648/j.earth.20221105.11
Page(s) 232-249
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Yaoundé Group, Metasedimentary Rocks, Upper Continental Crust, Active Margin, Congo Craton

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    Victor Metang, Bernard Tassongwa, Rose Ngo Belnoun, Henri Appolinaire Kenzo, Myrianne Tawo Toussi, et al. (2022). Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications. Earth Sciences, 11(5), 232-249. https://doi.org/10.11648/j.earth.20221105.11

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    Victor Metang; Bernard Tassongwa; Rose Ngo Belnoun; Henri Appolinaire Kenzo; Myrianne Tawo Toussi, et al. Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications. Earth Sci. 2022, 11(5), 232-249. doi: 10.11648/j.earth.20221105.11

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    Victor Metang, Bernard Tassongwa, Rose Ngo Belnoun, Henri Appolinaire Kenzo, Myrianne Tawo Toussi, et al. Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications. Earth Sci. 2022;11(5):232-249. doi: 10.11648/j.earth.20221105.11

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  • @article{10.11648/j.earth.20221105.11,
      author = {Victor Metang and Bernard Tassongwa and Rose Ngo Belnoun and Henri Appolinaire Kenzo and Myrianne Tawo Toussi and Diane Marilyn Nkamga Mbakam and Lea Grace Tene Kengne and Legrand Joseph Tchop and Lucas Mouafo and Jean Pierre Tchouankoue},
      title = {Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications},
      journal = {Earth Sciences},
      volume = {11},
      number = {5},
      pages = {232-249},
      doi = {10.11648/j.earth.20221105.11},
      url = {https://doi.org/10.11648/j.earth.20221105.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.earth.20221105.11},
      abstract = {The tectonic evolution and provenance of the sediments from the Yaoundé Group remain poorly understood and somewhat enigmatic although the information it has already provided. This work presents the results of integrated field mapping, petrography and whole-rock geochemical studies of less documented metasedimentary rocks cropping in the southwestern portion of the Yaoundé Group, with the aim to enhance the geological setting of this group. These metasedimentary rocks comprise garnet-bearing chlorite schists, garnet micaschists and kyanite-bearing garnet migmatites. Their mineral assemblages suggest prograde metamorphism, from greenschist to granulite through amphibolite facies. Whole-rock geochemical data reveals wide range of Fe2O3 + MgO + TiO2 contents, from 7.3 to 32.6 wt.%, due to the diversity of lithological units. High Ba (616.833 ppm), V (145.333 ppm) and Zr (227.591 ppm) values suggest continental crust source materials. The average ratios of Nb/Ta (15.25), Zr/Hf (36.52) and Y/Ho (27.41) are closer to those of the upper continental crust. The average Th/U ratio, above 4.0 in investigated metasedimentary rocks, indicates intense weathering in the source areas or sediment recycling. The protoliths of the rocks are post-Archean shales and greywackes deriving mostly from andesites and granodiorites, probably from of the Congo craton and/or the Adamawa-Yadé block. The prominent tholeiitic geochemical affinity of these rocks suggests their emplacement in an active margin context and/or oceanic island arc setting.},
     year = {2022}
    }
    

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  • TY  - JOUR
    T1  - Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications
    AU  - Victor Metang
    AU  - Bernard Tassongwa
    AU  - Rose Ngo Belnoun
    AU  - Henri Appolinaire Kenzo
    AU  - Myrianne Tawo Toussi
    AU  - Diane Marilyn Nkamga Mbakam
    AU  - Lea Grace Tene Kengne
    AU  - Legrand Joseph Tchop
    AU  - Lucas Mouafo
    AU  - Jean Pierre Tchouankoue
    Y1  - 2022/09/05
    PY  - 2022
    N1  - https://doi.org/10.11648/j.earth.20221105.11
    DO  - 10.11648/j.earth.20221105.11
    T2  - Earth Sciences
    JF  - Earth Sciences
    JO  - Earth Sciences
    SP  - 232
    EP  - 249
    PB  - Science Publishing Group
    SN  - 2328-5982
    UR  - https://doi.org/10.11648/j.earth.20221105.11
    AB  - The tectonic evolution and provenance of the sediments from the Yaoundé Group remain poorly understood and somewhat enigmatic although the information it has already provided. This work presents the results of integrated field mapping, petrography and whole-rock geochemical studies of less documented metasedimentary rocks cropping in the southwestern portion of the Yaoundé Group, with the aim to enhance the geological setting of this group. These metasedimentary rocks comprise garnet-bearing chlorite schists, garnet micaschists and kyanite-bearing garnet migmatites. Their mineral assemblages suggest prograde metamorphism, from greenschist to granulite through amphibolite facies. Whole-rock geochemical data reveals wide range of Fe2O3 + MgO + TiO2 contents, from 7.3 to 32.6 wt.%, due to the diversity of lithological units. High Ba (616.833 ppm), V (145.333 ppm) and Zr (227.591 ppm) values suggest continental crust source materials. The average ratios of Nb/Ta (15.25), Zr/Hf (36.52) and Y/Ho (27.41) are closer to those of the upper continental crust. The average Th/U ratio, above 4.0 in investigated metasedimentary rocks, indicates intense weathering in the source areas or sediment recycling. The protoliths of the rocks are post-Archean shales and greywackes deriving mostly from andesites and granodiorites, probably from of the Congo craton and/or the Adamawa-Yadé block. The prominent tholeiitic geochemical affinity of these rocks suggests their emplacement in an active margin context and/or oceanic island arc setting.
    VL  - 11
    IS  - 5
    ER  - 

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Author Information
  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Dschang, Dschang, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

  • Department of Earth Sciences, Faculty of Science, University of Yaounde I, Yaounde, Cameroon

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