Lithostructural controls in Douala-Buea Region landscape (SW Cameroon margin): Insights from morphometric analysis

Lithostructural controls in Douala-Buea Region landscape (SW Cameroon margin): Insights from morphometric analysis

The Douala-Buea Region (DBR; 4°–5°N, 9°–10°30′E), a portion of the southern Cameroon passive margin, developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcano-sedimentary cover, was explored in order to evaluate the lithology and tectonics controls on its landscape...

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Bibliographic Details
Published in:Journal of mountain science 2021, Vol.18 (1), p.68-87
Main Authors: Balla Ateba, Christian, Owona, Sébastien, Nsangou Ngapna, Moussa, Manga Tsimi, Véronique, Minyem, Dieudonné, Mvondo Ondoa, Joseph
Format: Article
Language:eng
Subjects:
Analysis
Asymmetry
Coastal plains
Concavity
Cretaceous
Digital Elevation Models
Drainage patterns
Drainage systems
Earth and Environmental Science
Earth Sciences
Ecology
Elongation
Environment
Geography
Geomorphology
Landscape
Lithology
Morphology
Morphometry
Mountains
Network analysis
Original Article
Passive margins
Plate tectonics
Precambrian
Qualitative analysis
Rivers
Sedimentary basins
Tectonics
Valleys
Volcanic activity
Volcanoes
Watersheds
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Summary:The Douala-Buea Region (DBR; 4°–5°N, 9°–10°30′E), a portion of the southern Cameroon passive margin, developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcano-sedimentary cover, was explored in order to evaluate the lithology and tectonics controls on its landscape using the qualitative and quantitative geomorphological analyses based on 30 m resolution Digital Elevation Models (DEM) and field evidences. This area displays an uneven and complex landscape differentiated into four morphological units: Douala, Nkondjock, Kumba and Buea Units. The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Campo sedimentary basin. The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement. The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau. The Buea Unit corresponds to the Mount Cameroon stratovolcano. The relief analysis through mountain-front sinuosity ( S mf, 1.19–1.43) and relative relief ratio ( R r, 0.10–2.31) vary from one unit to another. The drainage network analysis including drainage patterns, stepped longitudinal river profiles, the associated morphometric indexes, notably the concavity index (IC, 0.56–0.88), deviation ( D , 267–2912 m), basin asymmetry factor ( A f , 6.37–42.12), hypsometric integral (HI, 0.10–0.29), valley floor width to valley height ratio ( V f, 0.36–2.75), elongation ratio ( R e, 0.30–0.50), watershed slope ( S , 6.88–88.88) and stream length gradient index (SL, 0–3332) vary from one basin to another too. These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics. The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points, asymmetric basins, and fault reactivations, and highlights the tectonics activity that used to occur through the time and their control on the morphology. Together, they document the lithostructural controls on the DBR landscape evolution, extendable in the whole SW Cameroon margin.
ISSN:1672-6316
1993-0321