Sylvestre GANNO · UY1 Research Hub

Sylvestre GANNO

Maître de Conférences

76Publ.

STDept.

FSFaculty

Institution: University of Yaoundé I
Faculty
Department
Professional email: sylvestre.ganno@facsciences-uy1.cm

Scientific activity

Publication summary

Period: 2006–2026
Open access: 11
Types: 4
Publ.: 76

Journal Article · 67
Other · 7
Preprint · 1
Book Chapter · 1

Recurring keywords

geology
geochemistry

Researcher profile

Biography

Faculty researcher at the University of Yaoundé I. Grade: Maître de Conférences.

Scientific publications

Publications

2026

2026Journal article
Safety monitoring and management system for Lagdo Dam, North Cameroon
Sylvie Durande Djikam Patipe, Philémon Zo’o Zame, Dieudonné Bisso, Yasmina Boussafir, Guillaume Veylon, Sylvestre Ganno
Discover Applied Sciences
The Lagdo dam in northern Cameroon, built between 1978 and 1984 with an initial capacity of 72 MW (now reduced by half), is the primary source of hydroelectric power for the northern grid. This 40 m high embankment dam (190 m base width, 10 m crest width) holds 7.7 billion dm³ of water. Its core is composed of clayey sand, complemented by horizontal filters and drains, while granite and gneiss riprap protect the embankments. Despite its strategic importance, the Lagdo Dam lacked a safety monitoring system based on international standards. Instrumentation records piezometric fluctuations with early operational peaks followed by recent declines. Displacement monitoring shows initial significant horizontal and vertical movements, stabilizing over the last two decades. Visual inspections revealed several anomalies including cracks, embankment degradation, overgrown vegetation, termite mounds, erosion traces, and water leaks, all of which compromise the safety of the structure. The over 40-year-old Lagdo Dam is classified as a Class A dam, and its monitoring system must comply with international standards. In addition to routine inspections, it is crucial to include scheduled, special and in-depth inspections.
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2025

2025Journal article
Integrated analysis of landslide susceptibility: geotechnical insights, frequency ratio method, and hazard mitigation strategies in a volcanic terrain
Brigitte Momene Tuwa, Donald Hermann Fossi, Aubin Nzeugang Nzeukou, Sylvestre Ganno, Désiré Tsozué
Arabian Journal of Geosciences
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2025Journal article
Late Stenian–Tonian magmatic signatures and provenance of metasedimentary rocks from the Deng-Deng area, East Cameroon
Donald Hermann Fossi, Jonas Didero Takodjou Wambo, Evine Laure Tanko Njiosseu, Patrick Ayonta Kenné, Sylvestre Ganno, Jean Paul Nzenti
Journal of African Earth Sciences
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2024

2024OtherOpen access
Geochemical and petrographic insights into the origin, weathering, and tectonic context of Deng-Deng metasedimentary rocks in the Central African Fold Belt.
Donald Hermann Fossi, Sylvestre Ganno, Evine Laure Tanko Njiosseu, Patrick Ayonta Kenné, Jean Paul Nzenti, Jonas Didero Takodjou Wambo
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2024Journal article
Geochemistry and U-Pb zircon geochronology of the Nkout banded iron formations and associated metasiliciclastic rocks, NW Congo craton, southern Cameroon
Lysiane Christelle Kouayep Tchoundi, Sylvestre Ganno, Landry Soh Tamehe, Arlette Pulcherie Djoukouo Soh, Donald Hermann Fossi, Jean Paul Nzenti
International Geology Review
The Nkout banded iron formations (BIFs)-hosted iron deposit is located in the Ntem Complex at the northwestern part of the Congo craton, southern Cameroon. We report geochronological and geochemical data of magnetite BIFs and interlayered mica schists from the Nkout iron ore deposit. The BIFs show typical features of chemical precipitates characterized by seawater-like shale-normalized rare earth elements plus yttrium spectra. Weak positive Eu anomalies indicate the contribution of high-temperature hydrothermal fluids to the BIFs, with low detrital input. The absence of true Ce anomalies indicates that the BIFs were likely to be deposited in anoxic seawater. LA-ICP-MS U-Pb detrital zircon data for the BIFs and associated metasiliciclasltic rocks constrained the maximum depositional age at ca. 2.8 Ga, suggesting that the Nkout BIFs are likely the oldest iron formations in the Ntem Complex. Our zircon U-Pb isotope data indicate that the Nkout succession experienced lower-amphibolite facies metamorphism at ca. 2.0 Ga, which correlates with the regional tectono-thermal event linked to the convergence and assembly of terranes between the Congo and São Francisco cratons during the Eburnean-Transamazonian orogeny.
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2023

2023Journal article
Mantle-crust-interaction and subduction dynamics in Central Cameroon: Evidence from the Pan-African Linté microgranular magmatic enclaves (MMEs) and host syenite
Patrick Ayonta Kenné, Sylvestre Ganno, Abimbola Chris Ogunyele, Jonas Didero Takodjou Wambo, Timoléon Ngnotué, Donald Hermann Fossi and 3 more
Lithos
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2023Other
Review for "Major, trace elements and <scp>Sr–Nd–Pb</scp> isotopes systematics of mafic dykes from the Figuil (northern Cameroon) and Léré (southwestern Chad) areas"
Sylvestre Ganno
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2022

2022Journal article
Anatexis of metadiorite from the Yaoundé area, Central African Orogenic Belt in Cameroon: implications on the genesis of in-source granodiorite leucosomes
Victor Metang, Emmanuel Nomo Negue, Sylvestre Ganno, Jonas Didero Takodjou Wambo, Marcel Astrid Ewolo Teme, Arnaud Cedric Teda Soh and 5 more
Arabian Journal of Geosciences
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2021

2021Journal article
Geochronology and petrogenesis of the Pan-African granitoids from Mbondo-Ngazi Tina in the Adamawa-Yadé Domain, Central Cameroon
Alexis Hamdja Ngoniri, Landry Soh Tamehe, Sylvestre Ganno, Timoléon Ngnotué, Zuxing Chen, Huan Li and 2 more
International Journal of Earth Sciences
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2021Journal article
Origin and tectonic setting of mafic magmatic enclaves from the Ngaoundal area, Adamawa-Cameroon: Insights from petrography and whole rock geochemistry.
Aliou Mamouda, Sylvestre Ganno, Guy Bertin, Takam Tchoupe, A Tedesco Steven, Motto Mbita and 3 more
China Geology
In this contribution, detailed field descriptions together with petrographic and bulk-rock major, trace and rare earth elements (REE) data are used to constrain the origin and geodynamic setting of the mafic magmatic enclaves (MMEs) recently discovered within the Pan-African Ngaoundal pluton, Adamawa area, central Cameroon. The investigated MMEs are dark-colored with chilled margins, and display medium to coarse-grain igneous textures. The mineral assemblage is either dominated by K-feldspar and carbonate (group I), or by amphibole and plagioclase (group II), though the overall mineral phases made of amphibole, plagioclase, K-feldspar, and biotite are similar to that of their host syenite but in different proportions. The MMEs in Ngaoundal area are foid-gabbro in composition with SiO<sub>2</sub> contents ranging between 41.52% and 43.74% and are contiguous with their host granitoids of intermediate composition (SiO<sub>2</sub>=57.52% to 58.98%). The host granitoid rocks are metaluminous, and belong to the shoshonitic series. Petrographic and geochemical data have revealed that the Ngaoundal MMEs derived from rapid cooling of hot injected lithospheric mantle-derived magma within cooler host granitoids magma and were emplaced in the intraplate geodynamic setting.
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2020

2020Journal articleOpen access
Depositional age and tectonic environment of the Gouap banded iron formations from the Nyong group, SW Cameroon: Insights from isotopic, geochemical and geochronological studies of drillcore samples
Landry Soh Tamehe, Chongtao Wei, Sylvestre Ganno, Carlos Alberto Rosière, Jean Paul Nzenti, Chesther Gatsé Ebotehouna and 1 more
Geoscience Frontiers
The discovery of the Gouap banded iron formations (BIFs)-hosted iron mineralization in the northwestern of the Nyong Group (Ntem Complex) in southwestern Cameroon provides unique insights into the geology of this region. In this contribution, we firstly report detailed study of geochemistry, isotopic and geochronology of well preserved samples of the Gouap BIFs collected from diamond drillcores. The Gouap BIFs consist mainly of amphibole BIFs and amphibole–pyrite BIFs characterized by dominant Fe2O3 + SiO2 contents and variable contents of CaO, MgO and SO3, consistent with the presence of amphibole, chlorite, epidote and pyrite, formed during amphibolite facies metamorphism and overprinted hydrothermal event. The amphibole–pyrite BIFs are typically enriched in trace and rare earth elements (REE) compared to the amphibole BIFs, suggesting the influence of detrital materials as well as secondary hydrothermal alteration. The Post Archean Australian Shale (PAAS)-normalized REE–Y profiles of the Gouap BIFs display positive La, Eu anomalies, weak negative Ce anomalies, indicating a mixture of low-temperature hydrothermal fluids and relatively oxic conditions probably under relative shallow seawater. We present here the first isotopic data of BIFs within the Ntem Complex. The δ30SiNBS28 values of the quartz from the Gouap BIFs vary from −1.5‰ to −0.3‰ and from −0.8‰ to −0.9‰ for the amphibole BIFs and amphibole–pyrite BIFs, respectively. The quartz has δ18OV-SMOW values of 6.8‰–9.5‰ (amphibole BIFs) and 9.2‰–10.6‰ (amphibole–pyrite BIFs). The magnetite from the Gouap BIFs shows δ18O values ranging from −3.5‰ to −1.8‰ and from −3‰ to −1.7‰ for the amphibole BIFs and amphibole–pyrite BIFs, respectively. Moreover, the pyrite grains in the amphibole–pyrite BIFs display δ34S values of 1.1‰–1.8‰. All isotopic data of the Gouap BIFs confirm that they might have precipitated from low-temperature hydrothermal fluids with detrital input distant from the volcanic activity. According to their geochemical and isotopic characteristics, we propose that the Gouap BIFs belong to the Superior type. In situ U–Pb zircon dating of BIFs was conducted to assess the BIF depositional age based on strong evidence of zircon in thin section. The Gouap BIFs were probably deposited at 2422 ± 50 Ma in a region where sediments extended from continental shelf to deep-water environments along craton margins like the Cauê Formation of the Minas Supergroup, Brazil. The studied BIFs have experienced regional hydrothermal activity and metamorphism at 2089 ± 8.3 Ma during the Eburnean–Transamazonian orogeny. These findings suggest a physical continuity between the protocratonic masses of both São Francisco and Congo continents in the Rhyacian Period.
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2019

2019Journal articleOpen access
A Gondwana pre-break up related magmatism in Bafoussam area, west Cameroon: source characteristics and 40Ar/39Ar geochronology
Gus Djibril Kouankap Nono, Pierre Wotchoko, Evine Laure Tanko Njiosseu, Sylvestre Ganno, Joëlle Flore Tene Djoukam, Yannick Seplong and 1 more
International Journal of Advanced Geosciences
The Gondwana pre-break up related formations in Bafoussam area are transitional calc-alkaline doleritic dykes exhibiting high Alumina and low Ti-Mg contents. Their REE compositions are similar to those of E-MORB (Nd/Nb≈1, Zr/Nb≤20). A high partial melting of about 20% of Garnet peridotites source having primitive mantle composition, is inferred to the studied rocks. They are slightly evolved 50<Mg#<54, and its clinopyroxenes are augite of high temperature (600°C-1100°C). The studied dykes were emplaced in a within-plate tectonic setting and yield a 40Ar-39Ar plateau ages of 229±7Ma. These ages are slightly different from those of dolerites from the Oban-Obudu massif (Nigeria), from the basaltic dyke of the Cameroon Volcanic Line and from the Karoo-Ferrar mafic magmatism, all interpreted as magmatism that preceded the break-up of Gondwana. The emplacement age of 229±7Ma of dolerites from Bafoussam area relates them to the very early stage of Gondwana pre-break up magmatism in central Africa.
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2019Journal article
Geochemical constraints on the origin and tectonic setting of the serpentinized peridotites from the Paleoproterozoic Nyong series, Eseka area, SW Cameroon
Philomène Nga Essomba Nga Essomba Tsoungui, Sylvestre Ganno, Evine Laure Tanko Njiosseu, Jean Lavenir Ndema Mbongue, Brice Kamguia Woguia, Landry Soh Tamehe and 2 more
Acta Geochimica
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2018

2018Journal article
Geochemical Constraints on the Origin of Banded Iron Formation‐Hosted Iron Ore from the Archaean Ntem Complex (Congo Craton) in the Meyomessi Area, Southern Cameroon
Sylvestre Ganno, Désiré Tsozué, Gus Djibril Kouankap Nono, Milan Stafford Tchouatcha, Timoléon Ngnotué, Ruth Gamgne Takam and 1 more
Resource Geology
Abstract Banded iron formations (BIFs) are the most significant source of iron in the world. In this study, we report petrographic and geochemical data of the BIF from the Meyomessi area in the Ntem Complex, southern Cameroon, and discuss their genesis and the iron enrichment process. Field investigations and petrography have revealed that the studied BIF samples are hard; compact; weakly weathered; and composed of magnetite, subordinate quartz, and geothite. The geochemical composition of the whole rock reveals that iron and silica represent more than 98 wt% of the average composition, whereas Al 2 O 3 , TiO 2 , and high‐field strength elements (HFSE) contents are very low, similar to detritus‐free marine chemical precipitates. The total iron (TFe) contents range from 48.71 to 65.32 wt % (average of 53.29 wt %) and, together with the low concentrations of deleterious elements (0.19 wt % P on average), are consistent with medium‐grade iron ores by global standards. This interpretation is confirmed by the SiO 2 /Fe 2 O 3total versus (MgO + CaO + MnO)/Fe 2 O 3total discrimination plot in which most of the Meyomessi BIF samples fall in the field of medium‐grade siliceous ore. Only one sample (MGT94) plots in the high‐grade magnetite–geothite ore domain. The high Fe/Ti (376.36), Fe/Al (99.90), and Si/Al (29.26) ratios of the sample are consistent with significant hydrothermal components. The rare earth elements (REE) contents of the studied BIF samples are very low (∑REE: 0.81–1.47 ppm), and the Post‐Archaean Australian Shale (PAAS)‐normalized patterns display weak positive Eu anomalies (Eu/Eu*: 1.15–1.33), suggesting a syngenetic low‐temperature hydrothermal solutions, similar to other BIF worldwide. However, the Meyomessi BIFs show high Fe contents when compared to the other BIFs. This indicates an epigenetic mineralization process affected the Meyomessi BIF. From the above results and based on the field and analytical data, we propose that the genetic model of iron ores at the Meyomessi area involves two stages of the enrichment process, hypogene enrichment of BIF protore by metamorphic and magmatic fluids followed by supergene alteration as indicated by the presence of goethite in the rocks.
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2017

2017Journal article
Contrasting Pan-African structural styles at the NW margin of the Congo Shield in Cameroon
Boniface Kankeu, Reinhard O. Greiling, Jean Paul Nzenti, Sylvestre Ganno, Prince Y.E. Danguene, Jean Bassahak and 1 more
Journal of African Earth Sciences
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2016

2016Journal article
A mixed seawater and hydrothermal origin of superior-type banded iron formation (BIF)-hosted Kouambo iron deposit, Palaeoproterozoic Nyong series, Southwestern Cameroon: Constraints from petrography and geochemistry
Sylvestre Ganno, Njiosseu Tanko Evine Laure, Kouankap Nono Gus Djibril, Djoukouo Soh Arlette, Cyriel Moudioh, Timoléon Ngnotué and 1 more
Ore Geology Reviews
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2016Journal article
Origin and paleoenvironment of Pleistocene–Holocene Travertine deposit from the Mbéré sedimentary sub-basin along the Central Cameroon shear zone: Insights from petrology and palynology and evidence for neotectonics
Milan Stafford Tchouatcha, André Njoya, Sylvestre Ganno, Réné Toyama, Paul Aubin Ngouem, Pierre Ricard Njiké Ngaha
Journal of African Earth Sciences
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2015

2015Journal articleOpen access
Geochemical Fingerprint and Iron Ore Potential of the Siliceous Itabirite from Palaeoproterozoic Nyong Series, Zambi Area, Southwestern Cameroon
Sylvestre Ganno, Cyriel Moudioh, Adjija Nzina Nchare, Gus Djibril Kouankap Nono, Jean Paul Nzenti
Resource Geology
Abstract The study area forms part of an emerging iron ore province of southern Cameroon. Geochemistry analyses reveal that the siliceous itabirite has a very simple chemical composition, with Fe 2 O 3 and SiO 2 representing more than 96 wt.% of the average composition; suggesting chemical precipitates of silica and iron. Low Al 2 O 3 and TiO 2 concentrations and a weak positive correlation between them point to a minor detrital component in the precipitated marine sediments. The Si/Al ratio (average 52.7) indicates the hydrothermal origin of the studied itabirite. The Al–Si discrimination diagram supports this interpretation through the plot of all data in the hydrothermal field. The studied samples have low iron content (about 39.32% Fe), high gangue content (40.97% SiO 2 and 1.3 % Al 2 O 3 ) and low concentration of the deleterious elements (0.16 % P and < 0.01% S). The main gangue mineral is silica which can be efficiently removed from iron ores during preparation of raw materials for the blast furnace process. According to commercial standards for crude iron ores, it may be concluded that the Zambi iron ores are a low‐grade magnetic ore that can be profitably exploited for the production of iron for steel production.
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2014

2014Journal article
Paleoproterozoic Synkinematic Magnesian High-K Magmatism from the Tamkoro-Bossangoa Massif, along the Bossangoa-Bossembele Shear Zone in North-Western Central African Republic
Prince Emilien Danguene, Timoléon Ngnotué, Sylvestre Ganno, Jean Biandja, Boniface Kankeu, J.P. Nzenti
Journal of Geosciences and Geomatics
The magnesian high-K calc-alkaline intrusive of the Tamkoro-Bossangoa Massif, North Western Central African Republic, were synkinematically emplaced in a sinistral strike-slip shear zone of Paleoproterozoic age. The rock sequences consist of orthogneisses with abundant coarse- to medium-grained quartz monzodiorite, quartz diorite and medium- to fine-grained biotite granite composition and cover a range of about 55 to 76 wt.-% SiO2. They display characteristics of shoshonitic and high-K calc-alkaline series. Quartz monzodiorite and quartz diorite are metaluminous, whereas granite is moderately peraluminous (1≤ A/CNK ≤ 1.1) and plot in the field of I-type granitoids. Major and trace element composition of the granitoids indicate that the source materials were derived from different crustal protoliths. Major and trace element composition are consistent with the magmatism which may have involved remelting of (1) a composite metagreywackes protolith in the upper crust and (2) amphibolitised high-K calc-alkaline basaltic andesites in the central domain of the NEFB (North Equatorial Fold Belt). SHRIMP zircon and titanite dating of granitic rocks gives a magmatic zircon and titanite age of 2069 ± 9.6 Ma and 2063 ± 28 Ma respectively, a metamorphic age of 500 Ma and 597 Ma. The plutonic rocks of Tamkoro-Bossangoa area resemble other Paleoproterozoic high-K calc-alkaline syntectonic plutons in western and central . They also display strong similarities with high-K calc-alkaline plutons of eastern and of the in NE Brazil.
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2013

2013Journal article
Petrochemical Characterization of Two Distinct Types of Dolerites from Bafoussam Area, West Cameroon
Gus Djibril Kouankap Nono, Pierre Wotchoko, Sylvestre Ganno, Divine Ngong Njinchuki, Jean Paul Nzenti
International Journal of Geosciences
Two petrochemical types of doleritic dykes have been distinguished in Bafoussam area: 1) the olivine-bearing dolerites which are the most representative are dark green, showing characteristics of alkaline basalts and, 2) the calcite-bearing dolerites are grayish green, showing characteristics of tholeiitic basalts. The studied dolerites are less differentiated (1 FeOt/MgO 2); they present the evolution of a subalkaline magma following a calc-alkaline series (alkaline dolerites) and the tholeiitic series (tholeitiic dolerite). The chondrite normalized multielement spider diagrams of all the dolerites show a pronounced depletion in Ba, Th, and enrichment in Rb. Their geotectonic context is inferred to be intraplate and the contrast between the two types is probably due to a diverse source: crustal source for calcite-bearing dolerites and mantle source for olivine-bearing dolerites.
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2012

2012Journal article
Geochemistry and Geochronology of Peraluminous High-K Granitic Leucosomes of Yaound&#233; Series (Cameroon): Evidence for a Unique Pan-African Magmatism and Melting Event in North Equatorial Fold Belt
Timoléon Ngnotué, Sylvestre Ganno, Nzenti Jean Paul, Schulz Bernhard, Tchaptchet Tchato Depesquidoux, Suh Cheo Emmanuel
International Journal of Geosciences
Geochemical and geochronological studies have been carry out on the leucosomes of Yaoundé series with the aims to identify the magma sources and to indicate their production periods and emplacement within the formations of the Pan-African North-Equatorial Fold Belt (PANEFB) in Cameroon. The Yaoundé series belongs to the Southern domain of the PANEFB and it is composed of migmatites in which two types of granitic leucosomes (in situ leucosomes and injected leucosomes) have been distinguished. These rocks display characteristic of calc-alkaline (in situ leucosomes) and high-K calc-alkaline to shoshonitic series (injected leucosomes). All the rocks are peraluminous with in situ leucosomes conform to S-type and injected leucosomes conform to I- and S-type granitoids. Major and trace elements composition reveal that in situ leucosomes derived from the partial melting of the host metapelite whereas injected leucosomes derived from the melting of metagreywacke. These sources are similar to those of granitoids from central and northern domains of the PANEFB. Th-U-Pb dating by electron microprobe (EMP) and LA-ICP-MS U-Pb dating on zircon have been used to constraints the melting event and emplacement of leucosomes in Yaoundé series. Th-U-Pb monazite dating, undertaken in two samples of leucosomes, gives two groups of monazite ages. The older group gives an age of 658 Ma whereas the age of younger group is 592 Ma. U-Pb dating of zircons from the leucosomes reveals a Pan-African age ranging from 626 to 654 Ma whereas zircons from metapelitic host rock reveal the overprinting of an early Pan-African event 911 - 1127 Ma on Palaeoproterozoic (2127 Ma) inheritance. These data clearly indicate that the host rocks of leucosomes of Yaoundé series have been firstly metamorphosed during Tonien-Stenien period (911 - 1127 Ma) and reveal the existence of extended unique melting event (592 and 658 Ma) in the Yaoundé series which is contemporaneous with the magmatism responsible for the emplacement of granitoids in the other domains of the PANEFB.
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2011

2011Journal article
Fibrous quartz vein filling from a shear zone in cameroon
Gus Djibril Kouankap Nono, Sylvestre Ganno, Cheo Emmanuel Suh, J.P. Nzenti
Journal of Structural Geology
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2010

2010Journal article
Geochemistry of Ferriferous, High-K Calc-Alkaline Granitoids from the Banefo-Mvoutsaha Massif (NE Bafoussam), Central Domain of the Pan- African Fold Belt, Cameroon~!2009-11-12~!2010-01-05~!2010-03-11~!
Gus Djibril Kouankap Nono, Jean Paul Nzenti, Cheo Emmanuel Suh, Sylvestre Ganno
The Open Geology Journal
The ferriferous high-K calc-alkaline rocks of the Banefo-Mvoutsaha Massif, Pan-African Belt, Central Cameroon, were synkinematically emplaced in a sinistral strike-slip shear zone of Pan-African age. The rock sequences consist of orthogneises made of coarse-grained granites, quartz-monzonites, and medium-to fine-grained granodiorites, ranging from ca. 55 to 75 wt.-% SiO 2 . They display characteristics of shoshonitic and high-K calc-alkaline series. Orthogneises are metaluminous to peraluminous and show characteristics of I-type granitoids from a ferriferous series. Trace element distribution patterns reveal rocks enriched in LILE when compared to HSFE and distinctively depleted in Th, Nb, Ba, Sr, Ti and Ta. The data indicate that this granitic rock assemblage did not result from the simple differentiation of a common parental magma, but show that Banefo-Mvoutsaha plutonic rocks were derived from different crustal protoliths. Major and trace element composition are consistent with the magmatism which may have involved remelting of (1) a composite metagreywackes protolith in the upper crust and (2) amphibolitised high-K calc-alkaline basaltic andesites in the central domain of the PANEFB (Pan-African North Equatorial Fold Belt). The plutonic rocks of Banefo-Mvoutsaha area resemble other Neoproterozoic high-K calc-alkaline syntectonic plutons in Western Cameroon. They also display strong similarities with high-K calc-alkaline plutons of the Pernambuco shear zone in NE Brazil and Eastern Nigeria.
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2009

2009Journal article
Neoproterozoic metamorphic events in the kekem area (central domain of the Cameroon north equatorial fold belt): P-T data
TD Tchaptchet, P Nzeti, EL Njiosseu, Timoléon Ngnotué, Sylvestre Ganno
Journal of the Cameroon academy of sciences
The Kekem area (southwestern part of the central domain of the Cameroon North Equatorial Fold Belt) is composed of high-grade migmatitic gneisses in which two lithological units are distinguished: (i) a metasedimentary unit (garnet- sillimanite-biotite-gneisses and garnet-biotite-gneisses) interpreted as a continental series; and (ii) meta-igneous rocks comprising mafic pyroxene gneisses, amphibolites, and orthogneisses. These units recrystallised under HT-MP conditions (T=700-800‹C, P . 0.5-0.8GPa) and were deformed in relation to a major tangential tectonic event with the NNE-SSW kinematic direction. The lithological association and its tectono-metamorphic evolution show striking similarities with the Banyo and Maham III gneisses, suggesting that the extensional depositional environment envisaged for this formation can be extended farther west. P-T calculations in this contribution provide new data on the Pan-African structural and metamorphic evolution of the metapelites and metabasites in the basement of the Kekem area. The results show two distinct events: (1) crystallization during a Pan-African high temperature metamorphic event and, (2) subsequent deformation and high temperature mylonitization. The data imply a high-temperature amphibolite-facies metamorphism along a clockwise P-T path. The recorded P-T involves a marked variation in pressure, which is typical of collisional crustal thickening. The contrasted metamorphic evolution between areas located to the south of the Central Cameroon Shear Zone (CCSZ; high pressure: Yaounde, Ntui-Betamba), and those located to the north (low pressure: Banyo, Tibati), along with widespread remains of Paleoproterozoic crust, suggest important crustal thickening during Pan-African tangential tectonics in southern Cameroon. As a consequence, the CCSZ is not simply a late Pan-African transpressive shear zone but appears to have been formerly a major intracontinental thrust zone. Key words : HT metamorphic event / Kekem/ Cameroon / Collisional crustal thickening / Neoproterozoic / North Equatorial Fold Belt. La region de Kekem est formee de gneiss anatectiques de haut-degre dans lesquels deux ensembles sont reconnus: (i) un ensemble metasedimentaire (gneiss a grenat, sillimanite et biotite, et gneiss a grenat et biotite) considere comme depose a lLinterieur dLun continent, (ii) des roches meta-ignees comprenant des gneiss a grenat et pyroxene, des amphibolites de composition mafique, et des orthogneiss. Ces deux ensembles ont recristallise (T=700-800‹C, P. 0,5-0,8GPa) et ont ete deformes en relation avec un episode majeur de tectonique tangentielle de direction cinematique NNE-SSW. Cette association lithologique et son evolution tectono-metamorphique montrent une similitude remarquable avec les formations panafricaines de Banyo et Maham III du domaine central de la chaine, suggerant que le contexte extensif de depot envisage pour ces dernieres peut etre etendu plus a lLouest. Les donnees nouvelles sur lLevolution tectono-metamorphique des metasediments et des metabasites panafricains du socle de la region de Kekem mettent en evidence un metamorphisme panafricain de haute temperature suivi dLune mylonitisation a haute temperature dans le facies amphibolite de haut degre selon un chemin P-T horaire. Les conditions P-T enregistrees se caracterisent par une variation de pression typique dLun epaississement crustal. LLevolution metamorphique panafricaine contrastee entre le domaine au sud du cisaillement Centre Camerounais (CCC; haute pression: Yaounde, Ntui-Betamba) et le domaine nord-CCC (basse a moyenne pression: Banyo, Tibati) ainsi que la presence ubiquiste de reliques dLune croute ancienne paleoproterozoique, suggerent un important epaississement crustal, lors dLun episode de tectonique tangentielle. Le CCC nLest donc pas un simple accident panafricain transpressif, mais apparait bien avoir ete prealablement un chevauchement intracontinental majeur. Mots-cles : Metamorphisme de Haut degre/Kekem/ Cameroun/ Epaississement crustal/ Neoproterozoique / Chaine Nord Equatorial
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2006

2006Book chapter
A new practical and economical technique for the obtention of high quality thin section photographs with the help of a simple optical microscope
Nono Gus D. Kouankap, Sylvestre Ganno
Geo-Leo e-docs (Deutsche Initiative für Netzwerkinformation)
Microscopic study is an indispensable step in the determination of the petrographic characteristics of rocks. In Cameroon just like in most developing countries, simple polarizing microscopes of the 20th Century constitute the only available material for macroscopic studies. A major difficulty encountered in the use of these instruments resides in the realisation of photographs of the different parts of the thin section that require illustrations. The technique that has been used upto now has been inefficient and unsatisfactory. Faced with this recurrent situation, we thought of setting up a new, semi-modern, practical and very economical technique for photographing the thin section.
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2025Journal article

Reassessing tectono-structural units and crustal thickness variations in southwest Cameroon using satellite gravity and seismic data

Stephane Landry Kwega Ghomsi, Dieudonné Bisso, Sylvestre Ganno, Luan Thanh Pham, Róbert Tenzer, Franck Eitel Kemgang Ghomsi

Journal of African Earth Sciences

Southwest Cameroon has long lacked detailed geological data, prompting an investigation into its geological and tectonic features through innovative edge detection techniques applied to gravity data. We employed various methods, including the Analytical Signal (AS), Tilt Angle (TDR), Total Horizontal Gradient of the Tilt Angle (TDR_THDR), and the Logistic Filter (IL) to delineate geological features that manifest as lineaments and contacts on gravity anomaly maps. Main findings of this study involve identification of key tectonic boundaries, notably the Kribi-Campo faults (KCF) and the Ebolowa pseudo-karstic circular network, the latter being mapped for the first time. This work reveals the continuity of the Ebolowa network and integrates connections such as the Mbilibekon and Mfuda caves, enhancing our understanding of the region's geological evolution. Additionally, we detailed the north-south extension of the KCF, which extends into both oceanic and terrestrial domains, aligning with the eastern margin of the Congo Craton. This finding suggests the fault system's role as a transition between the stable cratonic core and the dynamic mobile belts, necessitating a re-evaluation of regional tectonic models. To support our edge detection interpretations, we estimated Moho depths using gravity and seismic data, finding a Moho depth range between 34.5 km to 45.9 km, correlating with significant faulting and sedimentary features. This research enhances the understanding of subsurface structures in Southwestern Cameroon and provides a robust foundation for future geological and geophysical studies, emphasizing the critical interplay between surface and subsurface processes.

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2024Journal article

Integration of airborne magnetic and geological data for mineral prospectivity mapping in the Ambam-Amvom rainforest area, Archean Ntem Complex, southern Cameroon

Habib Dadjo Djomo, Eric Deassou Sezine, Justine Yandjimain, Achille Simplice Tsassé Nganno, Donald Hermann Fossi, Désiré Tsozué and 1 more

Scientific African

The accurate mapping of mineral resources in rainforest areas is challenging due to dense vegetation and thick lateritic cover obscuring rock outcrops. This study utilized airborne magnetic survey data to map geological features and target mineral resources in the Ambam-Amvom area at the NW margin of the Congo craton. Linear and non-linear filtering algorithms were used, including reduction to equator (RTE), upward continuation (UC) at 1000 m and 2000 m, first vertical derivative (FVD), and analytic signal (AS). Field surveys were carried out for sampling and petrographic investigations. The TMI map showed magnetic signals varying from -4489 nT to 2317 nT, while the RTE map displayed magnetic signals varying from -2984 nT to 3528 nT. The RTE-Reg map exhibited anomaly signal variations ranging between -2704 nT and +3637 nT and between -2829 and +3864 nT, respectively for UC at 1000 m and 2000 m. Geological structures were interpreted from the FVD, AS, and TMI-RTE images, and linear structures of regional extend mainly trend NW-SE, E-W, and NE-SW. Field investigations revealed that the study area comprises iron formations, amphibolite, gneiss, gabbro, biotite granite, and charnockite. The bulk chemical composition of iron formations showed high content of TFe, averaging 39.80 wt.% for itabirite, 53.79 wt.% for hematite-geothite ore and 59.63 wt.% for quartz-hematite ore. The zones of peak magnetic anomalies coincided with the occurrence of greenstone belt, and the integration of aeromagnetic and geological data led to the identification of three main target zones for iron ore minimization. High fracture density zones within the research were identified as high prospective targets for gold mineralization. The study's findings highlight the high potential of the Ntem Complex for mineral resources and provide valuable information for future research and development.

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2024Journal article

Mineralization of Zr-REE-Y in the Ngaoumbol iron formations, central Cameroon: Insights from petrography, mineral chemistry and whole rock geochemistry

Guy Bertin Takam Tchoupe, Ekah Nzume Ndime, Donald Hermann Fossi, Arlette Soh Djoukouo, Milan Stafford Tchouatcha, Steven Arnold Mbita Motto and 2 more

Solid Earth Sciences

The increasing importance of rare earth elements (REE) and critical metals in contemporary society has led us to investigate the mineral potential of the Ngaoumbol area, located within Cameroon's Central African Fold Belt (CAFB). In this study, we have conducted a comprehensive analysis that includes petrography, whole rock geochemistry, and mineral chemistry, along with the application of an outlook coefficient known as Koult, with the aim to evaluate the prospectivity of the Ngaoumbol iron formations as a potential source of REE-Y resources. This coefficient is defined as the ratio of the relative abundance of critical Rare Earth Elements to the relative abundance of excess REE. The iron formations in the Ngaoumbol area are fine-to medium-grained foliated rocks with alternating magnetite and actinolite bands and quartz bands, suggesting a sedimentary parentage. These rocks have an average REE-Y content of 1438.43 ppm and a Koult of 0.77, indicating their potential as raw sources for REE. Furthermore, the investigated samples exhibit high average Zr content (7748 ppm), suggesting that the rocks may host potentially economic Zr ore. The Zr-REE-Y mineralization in the Ngaoumbol area is hosted in detrital zircon, monazite and xenotime, probably deriving from the weathering of alkaline/subalkaline rocks surrounding the deposits. Our findings suggest that the Ngaoumbol area has promising REE and Zr resources. However, further exploration and evaluation are necessary to determine the extent and economic viability of these resources.

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2021Journal article

Origin, tectonic environment and age of the Bibole banded iron formations, northwestern Congo Craton, Cameroon: geochemical and geochronological constraints

Arlette Pulcherie Djoukouo Soh, Sylvestre Ganno, Lianchang Zhang, Landry Soh Tamehe, Changle Wang, Zidong Peng and 2 more

Geological Magazine

Abstract The newly discovered Bibole banded iron formations are located within the Nyong Group at the northwest of the Congo Craton in Cameroon. The Bibole banded iron formations comprise oxide (quartz-magnetite) and mixed oxide-silicate (chlorite-magnetite) facies banded iron formations, which are interbedded with felsic gneiss, phyllite and quartz-chlorite schist. Geochemical studies of the quartz-magnetite banded iron formations and chlorite-magnetite banded iron formations reveal that they are composed of >95 wt % Fe 2 O 3 plus SiO 2 and have low concentrations of Al 2 O 3 , TiO 2 and high field strength elements. This indicates that the Bibole banded iron formations were not significantly contaminated by detrital materials. Post-Archaean Australian Shale–normalized rare earth element and yttrium patterns are characterized by positive La and Y anomalies, a relative depletion of light rare earth elements compared to heavy rare earth elements and positive Eu anomalies (average of 1.86 and 1.15 for the quartz-magnetite banded iron formations and chlorite-magnetite banded iron formations, respectively), suggesting the influence of low-temperature hydrothermal fluids and seawater. The quartz-magnetite banded iron formations display true negative Ce anomalies, while the chlorite-magnetite banded iron formations lack Ce anomalies. Combined with their distinct Eu anomalies consistent with Algoma- and Superior-type banded iron formations, we suggest that the Bibole banded iron formations were deposited under oxic to suboxic conditions in an extensional basin. SIMS U–Pb data indicate that the Bibole banded iron formations were deposited at 2466 Ma and experienced metamorphism and metasomatism at 2078 Ma during the Eburnean/Trans-Amazonian orogeny. Overall, these findings suggest that the studied banded iron formations probably marked the onset of the rise of atmospheric oxygen, also known as the Great Oxidation Event in the Congo Craton.

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2021Journal article

Zircon trace element geochemistry and Ti‐in‐zircon thermometry of the Linté Pan‐African granitoids, Central Cameroon: Constraints on the genesis of host magma and tectonic implications

Patrick Ayonta Kenné, Evine Laure Tanko Njiosseu, Sylvestre Ganno, Timoléon Ngnotué, Donald Hermann Fossi, Alexis Hamdja Ngoniri and 2 more

Geological Journal

The Linté area belongs to the central part of the Adamawa‐Yadé Domain (AYD) within the Pan‐African Central African Fold Belt (CAFB) in Cameroon. This area is dominated by Neoproterozoic high‐K calc‐alkaline syenite and monzonite intruding Archean to Palaeoproterozoic gneisses. In this contribution, trace element compositions of zircon obtained using laser ablation inductively coupled plasma mass spectrometry are used to constrain the petrogenesis and tectonic setting of Linté area. The analysed zircon grains display restricted ranges of Hf content s with an average of 8,197 ppm in syenite, 8,220 ppm in alkali‐feldspar syenite, and 9,026 ppm in monzonite. They display high Th/U ratios (>0.5) typical of magmatic zircons. The monzonite zircons have a higher ∑REE content (483.42 ppm) than the syenite zircons (237.70 ppm). The chondrite‐normalized rare‐earth element (REE) diagram of Linté samples shows very similar patterns, characterized by a steeply rising slope due to important heavy rare‐earth element enrichment relative to light rare‐earth element, with distinctive positive Ce and negative Eu anomalies. The application of the Ti‐in‐zircon thermometer reveals a wide range of crystallization temperatures (574–1,137°C for syenites and 713–1,008°C for monzonite), implying a deep level of melting, likely within the lower continental crust of the CAFB. The integration of geochemical behaviours of some trace elements (U, Hf, Zr, Ce, Th, and Nb), together with discrimination diagrams, suggests the crystallization of a continental crust‐derived magma under variable oxidation states and emplacement in a magmatic‐arc setting. This finding represents and adds on to the N‐S geodynamic convergence model between the AYD and the northern border of the Congo Craton.

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2020Journal article

Geochemistry of the Neoproterozoic Mbondo-Ngazi Tina Metasediments, Adamawa Area, Central Cameroon: Source Provenance and Tectonic Setting

Alexis Hamdja Ngoniri, Timoléon Ngnotué, Evine Laure Tanko Njiosseu, Patrick Ayonta Kenné, Sylvestre Ganno, Jean Paul Nzenti

Journal of Geosciences and Geomatics

The Mbondo-Ngazi Tina area belongs to the Adamawa-Yade domain within the Pan-African Central Africa Fold Belt in Cameroon (CAFB). The basement of this area is dominated by metasedimentary rocks composed of sericite schist, chlorite schist and muscovite schist. Whole-rock geochemical compositions of these rocks were investigated in order to determine their provenance and tectonic setting. The studied metasedimentary rocks have SiO2 and Al2O3 contents comparable to the average composition of the Neoproterozoic upper continental crust (UCC). These rocks are strongly depleted in CaO, MgO, and enriched in K2O, Ba and Rb with respect to UCC, reflecting K addition during diagenesis. The CIA, CIW, PIA and the SiO2/Al2O3 and Th/U ratios indicated that these rocks had suffered varying degrees of weathering as the source rocks underwent mild to moderate chemical weathering. The PAAS-normalized REE patterns are almost flat with slightly LREE depletion with respect to HREE and null to weakly positive Eu anomalies. Their chondrite-normalized REE patterns are parallel to sub-parallel, LREE-enriched, and display distinct negative Eu anomalies and weakly fractionated HREE segments. Overall, they are geochemically mature and have suffered sedimentary recycling. They derived mainy from felsic to intermediate rocks with minor contamination of mafic rocks. The Mbondo-Ngazi Tina metasedimentary rocks show REE and trace element compositions similar to those of Archean sediments, suggesting that the continental crust of the study area during the early Proterozoic had chemical compositions similar to those of the Archean crust and were probably deposited in active to passive continental margin settings.

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2020Journal article

Petrogenesis and tectonic setting of the Paleoproterozoic Kelle Bidjoka iron formations, Nyong group greenstone belts, southwestern Cameroon. Constraints from petrology, geochemistry, and LA-ICP-MS zircon U-Pb geochronology

Marvine Nzepang Tankwa, Sylvestre Ganno, Olugbenga Okunlola, Evine Laure Tanko Njiosseu, Landry Soh Tamehe, Brice Kamguia Woguia and 2 more

International Geology Review

The Kelle Bidjoka Iron Formations (IFs) occur at the northmost margin of the Neoarchean to Paleoproterozoic Nyong group greenstone belts in SW Cameroon. This contribution presents for the first time the petrographical, geochemical, and geochronological data of the Kelle Bidjoka IFs and associated metaigneous (metatonalite) and metasedimentary (pyroxene gneiss) rocks. The studied IFs form a thin unit of 3.21 m thick and comprise magnetite pyroxene gneiss, garnet-bearing magnetite pyroxene gneiss, pyroxene BIFs, and grunerite BIFs. Petrographic studies have revealed mineral assemblages indicating retrograde amphibolite facies metamorphism. Magnetite pyroxene gneiss and pyroxene BIFs show signatures of both seawater and hydrothermal fluids, with magnetite pyroxene gneiss deposited closer to the vent source. In contrast, garnet-bearing magnetite pyroxene gneiss and grunerite BIFs are devoid of hydrothermal characteristics and show significant crustal contamination. The lack of Ce anomaly in most samples indicates anoxic to suboxic conditions during their deposition. The geochemical characteristics of the associated metaigneous and metasedimentary rocks indicate that Kelle Bidjoka IFs were deposited in a submarine volcanic arc environment, similar to the Algoma-type BIFs. Detrital zircon LA-ICP-MS U-Pb dating suggests that the Kelle Bidjoka BIFs were deposited during early Paleoproterozoic (ca. 2423 Ma) and were metamorphosed up to granulite facies during the Eburnean/Transamozian (ca. 2050 Ma) orogeny.

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2014Journal article

Stream Sediment Geochemical Survey of Gouap-Nkollo Prospect, Southern Cameroon: Implications for Gold and LREE Exploration

Soh Tamehe Landry, Sylvestre Ganno, Kouankap Nono Gus Djibril, Timoléon Ngnotué, Boniface Kankeu, Nzenti Jean Paul

American Journal of Mining and Metallurgy

Stream sediments play a significant role in geochemistry exploration by identifying possible sources of anomalous element concentration. This work is the baseline stream sediments geochemical study which brings general information on the geochemical dispersion of the metal elements (especially gold) at Gouap-Nkollo prospect (SW Cameroon) with the aim of providing a useful guide for future exploration strategies. For this study a concentration of 47 elements was measured in 10 stream sediment samples using BLEG and ICP-MS methods, but emphasis was given to the following 21 chemical elements: Al, Ca, Fe, K, Mg, Na, P Ag, Au, B, Co, Cr, Cu, Mn, Ni, Ti, Zn, Ce, La Th, U and Zr. Averaged elemental concentration for each samples obtained by statistical analysis showing patterns of enrichment and depletion which may relate to localized mineralization conditions or local lithological changes. Results showed that the stream sediments have high concentrations of Au, Ce and La with average values of 314.85ppm, 19081ppm and 11808ppm respectively for gold, cerium and lanthanum. Cerium and Lanthanum have considerably high concentrations when compared with other Rare Earth Elements (REE) analyzed. These concentrations represent interesting indices for Au and LREE mineralization’s. The geochemical dispersion of the metal elements (especially gold) reveals that high concentrations are recorded in the northern part of the prospect, close to the quartz-tourmaline vein within the quartzite. This result indicates that the Au and other metal elements probably originated from the quartz-tourmaline veins hosted by surrounding rocks. Detailed exploration work including geochemical soil sampling and geophysical survey is highly recommended in the northern part of the Gouap-Nkollo prospect, where anomalous concentrations of Au were observed, for further investigation.

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2010Journal article

Synkinematic ferro-potassic magmatism from the Mekwene-Njimafofire Foumban Massif, along the Foumban-Banyo shear zone in central domain of Cameroon Pan-African fold belt

Adjija Chare Nzina, Jean Paul Nzenti, Evine Laure Tanko Njiosseu, Sylvestre Ganno, Timoléon Ngnotué

Journal of Geology and Mining Research

The ferriferous high-K calc-alkaline intrusive of the Mekwene-Njimafofire Foumban Massif, Central Cameroon, were synkinematically emplaced in a sinistral strike-slip shear zone of Pan-African age. The rock sequences consist of orthogneisses with abundant coarse- to medium-grained quartz monzodiorite, medium- to fine-grained quartz monzonite, granodiorite, and fine-grained biotite granite composition and cover a range of about 60 to 76 wt.-% SiO2. They display characteristics of shoshonitic and high-K calc-alkaline series. Quartz monzodiorite, quartz monzonite and granodiorite are metaluminous, whereas biotite-amphibole granite is moderately peraluminous (1≤ A/CNK £ 1.1) and plot in the field of I-type granitoids. Major and trace element composition and the Rb/Sr isotopic data of the granitoids indicate that the source materials were derived from different crustal protoliths. Major and trace element composition are consistent with the magmatism which may have involved remelting of (1) a composite metagreywackes protolith in the upper crust and (2) amphibolitised high-K calc-alkaline basaltic andesite in the central domain of the PANEFB (Pan-African North Equatorial Fold Belt). The plutonic rocks of Mekwene-Njimafofire area resemble other Neoproterozoic high-K calc-alkaline syntectonic plutons in western and central Cameroon. They also display strong similarities with high-K calc-alkaline plutons of eastern Nigeria and of the Borborema Province in NE Brazil. Key words: Metaluminous and peraluminous granitoids, orthogneisses, ferriferous series, I-type granite, high-K calc-alkaline rocks, crustal source, Pan-African fold belt, Cameroon.

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Sylvestre GANNO

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