TITLE:
Structural and Chemical Characteristic of Tourmaline, and Mineralogy of Associated Micas from Tourmaline Bearing Quartzite of Kombé II (Bafia Group, Central Africa Fold Belt); Implication on the Metamorphic Conditions
AUTHORS:
Ganwa Alembert Alexandre, Klötzli Urs, Tchakounté Numbem Jacqueline, Klötzli Eva, Ertl Andreas, Djom Bernard
KEYWORDS:
Fe-Dravite, Structure Refinement, Accessory Mineral, Metamorphic Condition, Kombé II, Bafia Group, Central African Fold Belt
JOURNAL NAME:
International Journal of Geosciences,
Vol.13 No.10,
October
24,
2022
ABSTRACT: Bafia Group is part of the southernmost portion of
the Central African Fold Belt (CAFB) in Cameroon. The geological feature of the
group is characterized by the presence of metamorphic rocks in which tourmaline
had been recognized among accessory minerals. In the present study, attention
is focus on the tourmaline bearing quartzite to the southeast of Kombé II.
Structure refinement shows that
tourmaline is a Fe-dravite with the formulaX(Na0.95[]0.05)Y(Mg2.39Fe0.61)Z(Al5.10Mg0.90)(BO3)3T[Si6O18](OH)3[(O,OH)0.88F0.12].
The Fe-dravite is hosted in a Ca-poor quartzite, which is made up, in addition
to quartz and tourmaline, of biotite and muscovite. The structure of the
dravites shows a low vacancy at the X site, which militates for a
crystallization of the tourmaline at a high temperature > 750℃. This is in agreement with previous work which shows that the
metamorphic peak in the associated biotite gneiss reaches 825℃. The R1 value of 1.24% means that the
crystal structure of the tourmalines is of high quality. The genetical link
between gold mineralization and tourmaline should stimulate exploration
interest in the study area.