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.
Highlights
The Cameroon Volcanic Line (CVL) is one of the major geological lineaments of the African plate and continent [1]
Numerous researchers have worked on the CVL and most attention is directed towards the genesis, petrogenesis and petrology, geochronology, and emplacement mechanisms of the volcanic rocks [2,3,4,5,6,7] and other references therein]
This paper presents new data showing the peculiarities in ground and surface water of Sabga due to enrichment and its non conformance to the chemistry of acid volcanic rocks which constitute the main lithology in the area
Summary
The Cameroon Volcanic Line (CVL) is one of the major geological lineaments of the African plate and continent [1]. This N30 ̊E magmato-tectonic megastructure of Central Africa is a paradigm of active hot lines on Earth made up of continental and oceanic sectors; a unique feature in Africa and even in the world [2]. The Sabga-Bamessing area is a small locality on the west Cameroon highlands an extinct volcanic center of the CVL. The Sabga-Bamessing area conforms to the general geology of the CVL but has certain peculiarities. Explosive volcanic activity evident by the presence of extensive ignimbrite sheets characterizes the area [8].
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