TITLE:
Carbonate Enrichment in Volcanic Debris and Its Relationship with Carbonate Dissolution Signatures of Springs in the Sabga-Bamessing, North West, Cameroon
AUTHORS:
Raymond Beri Verla, Germain M. M. Mboudou, Olivier Njoh, Gilles Nyuyki Ngoran, Aloysius Ngambu Afahnwie
KEYWORDS:
Cameroon Volcanic Line (CVL); Carbonate Enrichment; Carbonate Dissolution; Weathering
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.1,
January
23,
2014
ABSTRACT:
Sabga-Bamessing is a part of the
Bamenda Mountains, an extinct volcanic center of the West Cameroon Highlands
along the Cameroon Volcanic Line (CVL). The pristine volcanic rocks of the
Sabga area are alkali mafic to felsic (basanites, phonolites, trachytes and
rhyolites). Some weathered sections of a heterolithologic debris flow with a
suppositious primary chemistry of the original volcanic rocks prior to
weathering have shown significant calcium carbonate enrichment. CaO and LOI
values of up 61.31% and 41.72% respectively show corresponding
enrichment of 16.54 and 10.88, when compared with average fresh volcanic rocks.
Na+ normalized molar ratios computed from the chemistry of springs
and rivers show carbonate dissolution signature which is contrary to silicate
dissolution expected in acid volcanic rocks. Saturation indices (SI) calculated
with PHREEQC reveal that brackish to saline springs are supersaturated with
Calcite (CaCO3), Aragonite (CaCO3), Dolomite (CaMg(CO3)2 and Hydroxyl apatite (Ca5(PO4)3OH).
Recharging contributions to spring water chemistry deviate from those
produced by rock weathering, precipitation and evaporation/crystallization. An
enrichment process is therefore predicted as a recharging contributor to water
chemistry.