Papers by François Mvondo Owono
J'ai cheminé avec certains étudiants que j'ai trouvés en thèse ou qui m'ont trouvé et avec qui, j... more J'ai cheminé avec certains étudiants que j'ai trouvés en thèse ou qui m'ont trouvé et avec qui, j'ai eu des discussions franches de thésards. Je tiens à leur dire merci. Je pense à
Aspect géomorphologique du secteur Ouest de Yaoundé : existence d’une structure circulaire multi-anneaux dans la zone de Leboudi – Minkoameyos
Le plateau sud-camerounais est une plateforme d’une altitude moyenne de 700 m. Les massifs gneiss... more Le plateau sud-camerounais est une plateforme d’une altitude moyenne de 700 m. Les massifs gneissiques les plus marquants, qui culminent a plus de 1000 m d’altitude, s’individualisent a l’Ouest de Yaounde, dans la zone de Leboudi-Minkoameyos. Les travaux de geomorphologie notamment ceux sur l’orographie montrent que ces massifs sont concentriques et decrivent une structure circulaire multi-anneaux de 19 km de diametre et de 418 m de profondeur, situee au Sud-Est de la depression elliptique de Yaounde. Deux anneaux sont mis en exergue, un anneau externe quasi circulaire de 19 km de diametre et un anneau interne circulaire de 8 km de diametre excentre vers le Sud. Ces anneaux sont separes par des vallees d’altitudes en decroissance centripete illustrant un relief etage. L’analyse hydrographique revele un reseau general de type dendritique, seconde par des reseaux rectangulaire, colineaire, parallele. Au niveau de la structure circulaire, se developpe un reseau particulier de type radi...
The region Lolodorf is a portion of the movable area Eburnean owned unit of the Nyong Complex of ... more The region Lolodorf is a portion of the movable area Eburnean owned unit of the Nyong Complex of Paleoproterozoic age. It is located between 3°10' and 3°25' N and 10°40' et 10°55' E and is part of Lokoundje watershed. The morphotectonic study in this area is based on a DEM to 90 m and no field data crossed through a geographic information system (GIS). The goal is to understand geological and climate controls of on the morphological evolution of that basin. Results show that major structural accidents oriented NNE-SSW to NE-SW and NW-SE to NNW-SSE and reactivation over time, combined with focused and violent drainage are the main factors that control these regional morphogenetic processes. Climate meanwhile, seems to control the fluvial incision and sculpture elements morphology related to changes in lithology and slope created by tectonics. ISSN 1029 –2225©2014 Sciences, Technologies et Developpement os
This paper aims to examine soft-sediment deformation structures occurred in MidCretaceous to Mid-... more This paper aims to examine soft-sediment deformation structures occurred in MidCretaceous to Mid-Tertiary deposits of the Centre East of the Douala sub-basin so as to understand the nature and the role of tectonics on their genesis. The studied sections are located along the railway sections of Loungahe, Pitti and also the roadside-cut along the "Nationale 3" (Missole), where detailed descriptions of the silico-clastic sediments show deformational structures called soft-sediment deformation structures (SSDS). These outcrops have been assigned the age from Cenomanian-Turonian to Paleocene-Eocene according to the literature reviewed here. Six main deformed sedimentary units that lie in between units of undeformed sediments were described. The deformed units show the various SSDS such as: 1) contorted structures which include irregular convolutes, turned-up concave structures, giant load structures, box folds, small overlapping, thrust structures, and folds of low amplitude; ...
The study of the geometric deposits in a basin allows the reconstitution of its tectonic and eust... more The study of the geometric deposits in a basin allows the reconstitution of its tectonic and eustatic history. The Rio-del Rey basin, upon which this study is being carried out, constitutes one of the two Cameroon margin basins located North of the Cameroon volcanic line. To study the stratigraphic architecture of the Miocene deposits consists in characterizing the deposits geometry by discriminating the controlling factors. This study is based on data, made up of 13 seismic lines and 07 wells and then on various methods related on seismostratigraphy and diagraphies. The obtained lithologies in the study area constituted essentially of sandy and clayey deposits from Paleocene to Recent. They are grouped differently in to Akata, Agbada and Benin Formations, and the Isongo Member. These deposits are set up in marines (bathyal and neritic), deltaics, turbiditic cones slope and fluvial channels environments. Three second-orders sequences were identified (S1, S2 and S3), they are made up...
Subsidence et évolution thermique des bassins de la marge atlantique camerounaise : premiers résultats à partir des puits en mer du sous-bassin de Kribi-Campo (Marge passive Ouest Africaine, Golfe de Guinée)
L’histoire de la subsidence et de l’évolution thermique du sous-bassin de Kribi-Campo situé dans ... more L’histoire de la subsidence et de l’évolution thermique du sous-bassin de Kribi-Campo situé dans le Golfe de Guinée a été contrainte à l’aide de 10 puits en mer en utilisant la technique de délestage après décompaction. Quatre principales phases de subsidence ont été discriminées : la première, du Barrémien à l’Aptien (130–112 Ma); la deuxième, de l’Albien au Sénonien (112–65 Ma); la troisième, s'étendant du Paléocène au Miocène (65–5 Ma); et la quatrième du Pliocène au Pléistocène (5–2 Ma). Les cartes de quantité et de vitesse de subsidence et de sédimentation montrent une grande zone subsidente dans la partie ouest du bassin autour de Kribi. Le facteur d’extension β pour le modèle d’extension uniforme correspond à des valeurs allant de 1,04 à 1,06. Graphiquement, les courbes de subsidence tectonique apparaissent encadrées par les courbes correspondant à β = 1,03 et β = 1,09. Les pentes des courbes linéaires de la subsidence tectonique par rapport à la racine carrée du temps, t...
SN Applied Sciences, 2020
This paper investigates the use of bauxite widely available in northern Cameroon as an additive i... more This paper investigates the use of bauxite widely available in northern Cameroon as an additive in the optimization of some properties of metakaolin-based geopolymer. To do this, several geopolymer mixtures were prepared by substituting metakaolin (MK) by bauxite (BA) (from 0 to 50%) and partially kept at room temperature (28 °C), while others were sintered at 200, 800 and 1200 °C. The raw materials and resulting products were characterized using X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), densification parameters, mechanical properties as well as microstructural morphologies. The results revealed that the setting time of the geopolymer pastes increased with the bauxite content due to its low dissolution in alkaline medium at room temperature. The mechanical strength of samples decreased from 35.20 to 11.10 MPa at room temperature. At 1200 °C, the higher strengths (50, 98 and 70 MPa) were achieved in MKBA10, MKBA20 and MKBA30, respectively. These samples also exhibited dense and compact microstructure partially due to packing particles effect and the nature of bauxite known as refractory material. Thermal shrinkage and relatively high mass losses reflected the decomposition of chemical compounds within the system. Thus, the synthesized materials heated at 1200 °C could be used as a potential candidate for refractory applications.
Tectono-stratigraphic evolution and architecture of the Miocene Rio del Rey basin (Cameroon margin, Gulf of Guinea)
International Journal of Earth Sciences, 2020
The Rio Del Rey basin located in the Gulf of Guinea is one of the two basins lining the Camerooni... more The Rio Del Rey basin located in the Gulf of Guinea is one of the two basins lining the Cameroonian coast. It evolved since the Cenozoic in a tectono-magmatic and seismic complex setting. During the Miocene, this evolution was controlled by tectonics, relative sea level changes, basin filling and mantle dynamics. Two deposit megasequences of second order, MS1 and MS2, were pointed out. MS1 (lower Miocene), aggradational and corresponding to the Isongo turbidites deposited during a period of relative sea level drop registered two sequences of third order differentiated by the degree of channel incision: S1a (Aquitanian–Burdigalian), hardly incised and S1b (Serravallian), moderately incised. A double extension along N–S (Burdigalian) and NE–SW (Serravallian) directions responsible for a set of horsts and grabens, high subsidence and depocentres trending NW–SE affected these sequences. MS2 (middle to upper Miocene), progradational and corresponding to deltaic alternations deposited during a period of creation of available space were controlled by the tilting, wrenching, a second stretching phase and low sedimentary filling. MS2 recorded three cycles of 3rd order: S2a (lower Tortonian), S2b (upper Tortonian) and S2c (Messinian) differentiated by their morphology in ramp for S2a and S2b and slope for S2c. The formation of grabens and horsts and the tilting of the margin coincide with the high activity of the Cameroon volcanic line interpreted as a result of deep mantle dynamics affecting the inner Congo craton lithosphere. This architecture, which differs from those of the other basins of the Gulf of Guinea, partly explains the low oil production of this basin.
Earth Science Research, 2020
The quick-look and gas chromatography analyses were used for formation evaluation of four depth i... more The quick-look and gas chromatography analyses were used for formation evaluation of four depth intervals in a well (well A) located within the offshore of the Rio Del Rey basin. The results show 3 water reservoirs (R1 to R3) and 1 hydrocarbon reservoir (R4). The quick-look reveals that the hydrocarbon (oil and gas) reservoir is a shaley sandstone or a radioactive sandstone located between 4898-4932 Mmd which is filled by oil and gas and with a good porosity. The chromatographic gas ratio analysis reveals that the hydrocarbon reservoir is filled by a productive gas which may be a wet gas. The result provided by the gas chromatography is a false result probably due to its limitation which is that the hydrocarbon component must exist at the gaseous phase (C1-C5) to be detected and analyzed. The gas chromatography based its analysis only in the C1 to C5 range, in oil we have from C1 to C8.
Journal of Geography and Geology, 2018
Morphometric parameters extracted fromDEM (90 m) combined with field and literature data of Edéa ... more Morphometric parameters extracted fromDEM (90 m) combined with field and literature data of Edéa region, a portion of Cameroonian passive margin located between 3°43’ - 4°00 ’N and 10°00’ - 10°15’E, were used to constraint the present day landscape and forces that have acted and is currently acting on its evolving topography. The obtained results show that the Sanaga Fault is one of the main driver forces responsible for this evolution. Set up during the Pan-African orogeny, this fault which affects a good part of the Proterozoic basement and Tertiary sedimentary cover has developed two systems of secondary active faults different by their nature and characteristics, quite visible in the Edéa region: the Ekitté System, shearing normal faults with a N-S to NNE-SSW strike and the Sanaga-Batignol System shearing directional faults with a NW-SE strike. Most of these faults constitute the river beds and play iteratively, deeply affecting both the drainage system and the landscape. Morpho...
Journal of African Earth Sciences, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Geological Journal, 2019
The SW Cameroonian passive margin, a part of the Cameroon Low-Plateau, presents several topograph... more The SW Cameroonian passive margin, a part of the Cameroon Low-Plateau, presents several topographic levels cross-cut by the Sanaga Fault (SF), Benue Triple Junction and Cameroon Volcanic Line (CVL), three pre-and syn-rift tectonic features that are still active. This study carried out on the Edea-Eseka Region (EER) a portion of this margin (3 30 0-4 N, 10-10 55 0 E) aims to constrain the relationships between these features and the development of the morphology. Geomorphic indices, combined with field observations and supported by literature data show that the interactive activity of these structures constitutes the main force that controls the EER morphology. From West to East, EER consists of three morphotectonic units: the Coastal, Intermediate and Upper units. The Coastal unit built on the Douala-Kribi/Campo Basin (<65 Ma) and assigned to the Aptian South Atlantic rifting, exhibits low reliefs deeply incised. The Intermediate and Upper units are developed on the Nyong and Oubanguide crystallophyllian complexes during the Eburnean/Trans-Amazonian (2,400-1,750 Ma) and Pan-African (650-540 Ma) orogenies, respectively. The Intermediate unit with moderate reliefs registers a strong differential erosion, whilst the Upper unit records high-reliefs. Geomorphic indices, tectonic and recent seismic data reveal that the EER has been rejuvenated, experienced uplifts and tiltings synchronously with the main active phases of these features. The timing and magnitude of these activities vary from one unit to another. The morphotectonic model is consistent to the crucial tectonic phases: emplacement of SF (Palaeozoic), the breakup of Gondwana and erection of CVL (Cretaceous).
Geomorphology, 2019
Passive margins and associated inland areas display complex vertical displacements that have been... more Passive margins and associated inland areas display complex vertical displacements that have been abundantly described offshore but much less so onshore due to erosion. Planation surfaces are ubiquitous markers inland that can be used as a proxy both climatic conditions and changes in vertical displacements induced by both short (faults) and long (tilting, flexure) wavelength deformations. We propose 1) a synthetic typology of the planation surfaces driven by a genetic process (weathering versus mechanical erosion), and 2) a method to use these surfaces to map short and long wavelength deformations. This methodology was applied to the Namibian margin and inland plateau to quantify the Cenozoic deformation. The results show that the Namibian margin was affected by bulging during the Oligocene and by an E-W to NW-SE extension during the Late Miocene and Pliocene. The bulge is parallel to the shoreline with a wavelength of 300 km and an amplitude up to 500 m. After investigating the available deformation processes, we propose that an increase in the spreading rate along the mid-oceanic ridge during the Oligocene generated this bulging. The vertical displacement is partially maintained afterwards via isostasy because of mass loss generated by scarp retreat. A minimum average rate of scarp retreat of 5 km/Myr was calculated, which is high compared to the rates estimated in other places in the world. We ascribe this high value to the prior intense weathering period. Indeed, the alteration largely degraded the bedrock and facilitated the formation of the subsequent scarp. This study also reveals that the high reliefs of the Damara domain existed before the Cenozoic, induced by a reactivation of the Damara structures.
CATENA, 2016
The South Namibian Plateau, which belongs to the South African Plateau, is situated between 25°-2... more The South Namibian Plateau, which belongs to the South African Plateau, is situated between 25°-29°S and 15°-20°E. This study examines the relationships between this portion of the plateau and the development of planation surfaces and scarps bounding the plateau. Geomorphological analysis through morphometric indices extracted from a DEM (90 m) and its derived maps as well as field observations supported by the literature data permit the demonstration that tectonics, climate and base level are the main factors that control the formation and evolution of the planation surfaces and scarps that separate them. From west to east, the South Namibian Plateau consists of four main morphological provinces: the coastal province and the intermediate, upper and Kalahari provinces in the interior plateau. These provinces include five Cenozoic planation surfaces that are differentiated by their elevations, regional slopes, relative reliefs and erosion processes. These surfaces have been formed by etchplanation and pediplanation. The drainage pattern and river length profiles show that the coastal province evolved differently than the interior plateau. The development of the coastal province is controlled by eustasy and tectonics, whereas climate-related processes and tectonics control that of the interior plateau. The presence of several scarps separating these surfaces, the most degraded and older of which are inside the plateau, reflects a polyphase evolution. This evolution can be highlighted by two models: (1) an eastward migration mantle dynamics causing a slight uplift and rejuvenation of the system by destabilizing the coupled weathering/erosion equilibrium and (2) an internal propagation of isostatic rebound induced by the retreat of the western scarp leading to a significant flattening in the central part of the plateau.
J'ai cheminé avec certains étudiants que j'ai trouvés en thèse ou qui m'ont trouvé et avec qui, j... more J'ai cheminé avec certains étudiants que j'ai trouvés en thèse ou qui m'ont trouvé et avec qui, j'ai eu des discussions franches de thésards. Je tiens à leur dire merci. Je pense à
Cenozoic Landscape Evolution in and Around the Congo Basin: Constraints from Sediments and Planation Surfaces
Geology and Resource Potential of the Congo Basin, 2014
ABSTRACT
Comptes Rendus Geoscience, 2011
Intracontinental elevated plateaus remain geomorphologic features which are poorly studied. Their... more Intracontinental elevated plateaus remain geomorphologic features which are poorly studied. Their genesis requires a coupling between climate and deformation. The Fish River canyon (southern Namibia), the second largest canyon of the Earth, carved the South-African plateau on 550 m along 65 km. This study reveals that the upper and the lower segments are shaped by NE-SW and north-south grabens, respectively. These deformations increased the meandering and the vertical incision mainly in the lower canyon. However the river main trend was not drastically modified attesting that the river was ancient and that the rate of the vertical displacement was slow compared to the erosion rate. The main incision occurred during a NW-SE stretching of Plio-Pleistocene. These stretching episodes belong to two deformation phases previously poorly described in the South-African plateau. These widespread stretching phases are interpreted as a result of deep mantle dynamics affecting the inner African continent. ß 2011 Published by Elsevier Masson SAS on behalf of Acadé mie des sciences. R É S U M É Les plateaux intracontinentaux é levé s sont des objets gé omorphologiques peu é tudié s. Leur formation ré sulte d'un couplage subtil entre climat et dé formation. Le canyon de la riviè re Fish (Sud Namibie) a creusé le plateau sur 550 m le long de 65 km. Cette é tude ré vè le que les parties supé rieure et infé rieure du canyon sont structuré es par des grabens respectivement NE-SW et nord-sud. Ces dé formations ont permis le dé veloppement de mé andres et d'une incision verticale, notamment dans la partie infé rieure du canyon. Cependant, le cours principal de la riviè re n'a pas é té modifié attestant que la riviè re est ancienne et que le taux du dé placement vertical a é té lent par rapport au taux de l'é rosion. L'incision principale s'est produite au cours d'un é tirement NW-SE du Plio-Plé istocè ne. Ces é pisodes appartiennent à deux phases de dé formation mal dé crites sur le plateau sudafricain et sont interpré té s comme un ré sultat de la dynamique du manteau profond. ß 2011 Publié par Elsevier Masson SAS pour l'Acadé mie des sciences.
Open Journal of Geology, 2021
Alkaline basalts of Bafang and its environs are consisted of feldspars, olivines, pyroxenes and o... more Alkaline basalts of Bafang and its environs are consisted of feldspars, olivines, pyroxenes and oxides which appear as phenocrysts, microphenocrysts and microcrysts. Feldspars are plagioclases (An 67.97-15.84 Ab 69.19-30.43 Or 20.59-1.51) and anorthoclases (Ab 68.11-61.20 Or 33.87-20.91 An 10.98-4.93). Plagioclases are the most abundant amount these feldspars. Anorthoclases appear only in mugearite (BAF 3 and BAF 37) the most differentiated of the studied alkaline-basalts. In High Magnesian basalt, (HMg-B) plagioclases are labradorites (An 67.97-59.30 Ab 38.74-30.43 Or 2.75-1.60) and sanidine (An 45.44-31.82 Ab 62.66-51.79 Or 5.52-2.77), whereas in Low Magnesian basalt (LMg-B) there are labrador (
Journal of African Earth Sciences, 2018
Highlights Morphometric analyses and field survey were correlated in a GIS model. Drainage sy... more Highlights Morphometric analyses and field survey were correlated in a GIS model. Drainage system and landform parameters vary from one watershed to another. Morphology is controlled by lithology, tectonic, differential erosion and climate. Tectonic, lithology and climate control morphology in Central Africa.
Facies Analysis and Sequence Stratigraphy of Missole Outcrops: N’Kapa Formation of the South-Eastern Edge of Douala Sub-Basin (Cameroon)
Earth Science Research
Missole facies description and sequence stratigraphy analysis allow a new proposal of depositiona... more Missole facies description and sequence stratigraphy analysis allow a new proposal of depositional environments of the Douala sub-basin eastern part. The sediments of Missole outcrops (N’kapa Formation) correspond to fluvial/tidal channel to shallow shelf deposits with in some place embayment deposits within a warm and semi-arid climate. Integrated sedimentologic, palynologic and mineralogical data document a comprehensive sequence stratigraphy of this part of the Douala sub-basin. Five facies associations occur: (1) facies association I is characterized by Floodplain deposits; (2) facies association II is Fluvial to mouth bar deposits; (3) facies association III characterise Shallow Shelf deposits; (4) facies association IV represents Distal bay or Lacustrine déposits; and (5) Facies association V is made of Fluvial channel deposits. Six depositional sequences were identified. These sequences are composed of four progradational sequences and two retrogradational sequences containin...
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Papers by François Mvondo Owono