-
Petrography and Geochemistry of Metasedimentary Rocks from the Southwestern Portion of the Yaoundé Group in Cameroon: Provenance and Tectonic Implications
Victor Metang,
Bernard Tassongwa,
Rose Ngo Belnoun,
Henri Appolinaire Kenzo,
Myrianne Tawo Toussi,
Diane Marilyn Nkamga Mbakam,
Lea Grace Tene Kengne,
Legrand Joseph Tchop,
Lucas Mouafo,
Jean Pierre Tchouankoue
Issue:
Volume 11, Issue 5, October 2022
Pages:
232-249
Received:
9 August 2022
Accepted:
25 August 2022
Published:
5 September 2022
DOI:
10.11648/j.earth.20221105.11
Downloads:
Views:
Abstract: The tectonic evolution and provenance of the sediments from the Yaoundé Group remain poorly understood and somewhat enigmatic although the information it has already provided. This work presents the results of integrated field mapping, petrography and whole-rock geochemical studies of less documented metasedimentary rocks cropping in the southwestern portion of the Yaoundé Group, with the aim to enhance the geological setting of this group. These metasedimentary rocks comprise garnet-bearing chlorite schists, garnet micaschists and kyanite-bearing garnet migmatites. Their mineral assemblages suggest prograde metamorphism, from greenschist to granulite through amphibolite facies. Whole-rock geochemical data reveals wide range of Fe2O3 + MgO + TiO2 contents, from 7.3 to 32.6 wt.%, due to the diversity of lithological units. High Ba (616.833 ppm), V (145.333 ppm) and Zr (227.591 ppm) values suggest continental crust source materials. The average ratios of Nb/Ta (15.25), Zr/Hf (36.52) and Y/Ho (27.41) are closer to those of the upper continental crust. The average Th/U ratio, above 4.0 in investigated metasedimentary rocks, indicates intense weathering in the source areas or sediment recycling. The protoliths of the rocks are post-Archean shales and greywackes deriving mostly from andesites and granodiorites, probably from of the Congo craton and/or the Adamawa-Yadé block. The prominent tholeiitic geochemical affinity of these rocks suggests their emplacement in an active margin context and/or oceanic island arc setting.
Abstract: The tectonic evolution and provenance of the sediments from the Yaoundé Group remain poorly understood and somewhat enigmatic although the information it has already provided. This work presents the results of integrated field mapping, petrography and whole-rock geochemical studies of less documented metasedimentary rocks cropping in the southweste...
Show More
-
Assessment of Ecotourism Potentials in the North West Region of Cameroon
Fonge Beatrice Ambo,
Nfor Frederick,
Tabrey Hans Tata,
Enoh Christly Anyi-Nju
Issue:
Volume 11, Issue 5, October 2022
Pages:
250-259
Received:
9 August 2022
Accepted:
26 August 2022
Published:
8 September 2022
DOI:
10.11648/j.earth.20221105.12
Downloads:
Views:
Abstract: The tourism industry is playing an increasingly important role in the global economy, contributing 5 percent of Gross Domestic Product (GDP), 30 percent of service exports and 235 million jobs. In the world today, ecotourism has become a significant component in the lexicon of international development policy and assistance, referred to routinely as a potential new source of income for any area with a scenic landscape, whether natural or cultural. The North West Region of Cameroon is one of the most spectacular ecotourism destinations in the country and can be termed as an ecotourism cornucopia because of her richness in floral and faunal biodiversity, juxtaposed with beautiful undulating terrain, mountain, hills, caves, forests, water falls, lakes as well as an amazing cultural diversity. The main objective of this study was to identify and survey the ecotourism potentials in the North West Region of Cameroon. Data were obtained mostly through field survey though the use of questionnaires and focus group discussions were also employed. Also, secondary data sources were made used of. The data were analysed using SPSS Version 21 statistical package to produce simple charts for the interpretation of each of the sections in the questionnaires answered. The Microsoft Excel package was used to produce simple modules. The topographic map was drawn using Map Info. Pictures were edited and organized using Canon picture softwares, Zoombrowser and Photorecord respectively. Results revealed that the North West Region is endowed with 112 physical ecotourism potentials with Mezam Division having the highest number (33) followed by Bui Division with 19 ecotourism potentials while Menchum Division has the least with 8 ecotourism potentials. It is also within the North West Region that we find Mount Oku, the famous Oku Montane Forest which is a biodiversity hotspot covering some 20,000 hectares, offering floristic richness, endemic birds, and unique monkeys. Most of these potentials have not been developed largely due to inaccessibility constraints. Results also revealed that there are 10 active cultural festivals that occur in the region every year. Meanwhile, there has been the continuous development of the cultural potentials in all the divisions in the region because culture is part and parcel of a ‘Grassfield man’. This study therefore recommends a win win partnership between the government and the local councils through the new law on decentralization so as to ensure the constructions and maintenance of efficient road network to these ecotourism sites.
Abstract: The tourism industry is playing an increasingly important role in the global economy, contributing 5 percent of Gross Domestic Product (GDP), 30 percent of service exports and 235 million jobs. In the world today, ecotourism has become a significant component in the lexicon of international development policy and assistance, referred to routinely a...
Show More
-
Construction and Development of National Mineral Rock and Fossil Specimen Resource Center, China
Mei Yang,
Mingyue He,
Nan Xiao,
Zhiyuan Wu
Issue:
Volume 11, Issue 5, October 2022
Pages:
260-268
Received:
23 August 2022
Accepted:
4 September 2022
Published:
8 September 2022
DOI:
10.11648/j.earth.20221105.13
Downloads:
Views:
Abstract: National Mineral Rock and Fossil Specimen Resource Center (NMRFC) is an important infrastructure for the collection, management, sharing and preservation of geological specimen resources. It integrates the mineral rock and fossil specimens scattered in universities, scientific research institutes and museums in China in the field of geosciences in a standardized manner, establishes a specimen resource information platform by using modern information network technology, promotes the rational protection, scientific management and efficient sharing of specimen resources. By 2022, 301,790 specimen resources provided by 40 participants are shared on the website, including 125,873 fossils, 351,504 minerals, 107,843 rocks and 32,924 ores. Focusing on specimens and data, more than 200 thematic data sets and data products have been integrated, including China's typical ore deposits, China's prominent paleontological fossil groups, systematic mineralogy database, traditional Chinese medicine minerals database as well as gemstones and jade and so on. The NMRFC operates in a combination of online and offline ways, providing services for scientific and technological projects to support innovative research. It also plays an important role in gathering the resources of scientific research projects supported by national public finance. In view of the construction and sustainable development of the resource center, it is proposed to further strengthen the construction of incremental resources, comprehensively promote the construction of storage infrastructure, mine the potential value of data, and strengthen the construction of resource management capacity.
Abstract: National Mineral Rock and Fossil Specimen Resource Center (NMRFC) is an important infrastructure for the collection, management, sharing and preservation of geological specimen resources. It integrates the mineral rock and fossil specimens scattered in universities, scientific research institutes and museums in China in the field of geosciences in ...
Show More
-
Stratigraphic Order in the Sung Village-Len Bac Mountain Section, Yen Hoa Commune, Minh Hoa District, Quang Binh Province, North-Central Vietnam
Nguyen Huu Hung,
Nguyen Ba Hung
Issue:
Volume 11, Issue 5, October 2022
Pages:
269-276
Received:
5 August 2022
Accepted:
13 September 2022
Published:
28 September 2022
DOI:
10.11648/j.earth.20221105.14
Downloads:
Views:
Abstract: The Sung-Len Bac Mountain Section is one of the best section to study stratigraphy and paleontology of the Middle-Upper Devonian, Lower Carboniferous to Middle Permian sediments in North-central Vietnam, including formations in the ascending order: The Dong Tho Formation (D2-3 dt) is composed of silstone and quartz sandstone, 250m thick containing fish Bothiolepis sp, brachiopod? Holynetes caurongensis, tentaculite Homoctenus sp, plant Lepidodendropsis sp. of the Late Givetian-Early Frasnian. The Xom Nha Formation is composed of stylolitic limestone, 20m thick containing conodonts of the Palmatolepis glabra Zone of the Famennian age. The La Khe Formation is composed of silstone, shale, sandstone, cherty limestone bearing abundant crinoids, brachiopods, ammonoids, trilobites, plants of the Viséan age. The Muong Long Formation is composed of thick-bedded limestone over 1000m thick, containig foraminifers Millerella, Eostafella, Quydatella, Fusulinella, Obsoletes, Triticites, Schwagerina, Robustoschwagerina, Misellina, Neoschwagerina; and brachiopod Phricodothyris asiatica of the Carboniferous-Middle Permian age. An abundant fossil assemblage of plants Archaeocalamites sp., Sigillaria sp., Lepidodendron sp. associated with brachiopods Plicatifera sp., Chonetes sp., Lingula sp.; bivalve Mytilarca sp.; ammonoids Sulcogirtyoceras cf. limatum, Neoglyphioceras sp.; trilobites Linguaphillipsia cf. subconical, Phillipsia propiqua of nearshore facies has been found in the upper part of the La Khe Formation by the Hanoi Fossil Museum in 2022.
Abstract: The Sung-Len Bac Mountain Section is one of the best section to study stratigraphy and paleontology of the Middle-Upper Devonian, Lower Carboniferous to Middle Permian sediments in North-central Vietnam, including formations in the ascending order: The Dong Tho Formation (D2-3 dt) is composed of silstone and quartz sandstone, 250m thick containing ...
Show More
-
The Sliding Surface Investigation of in the West of Koyulhisar (Sivas, Turkey)
Sevda Ozel,
Demet Over,
Kemal Ozgur Hastaoglu
Issue:
Volume 11, Issue 5, October 2022
Pages:
277-288
Received:
23 August 2022
Accepted:
21 September 2022
Published:
28 September 2022
DOI:
10.11648/j.earth.20221105.15
Downloads:
Views:
Abstract: The study area covers approximately 200x250 m2. This area is one of the most active locations with the greatest landslide displacement amount. This study aims to determine the depth of the sliding surface with geophysical (seismic refraction tomography (SRT) and ground-penetrating radar (GPR)) methods. The results of the TUBITAK-111Y111 project were also used in this study. According to the geophysical results, three layers with average seismic P-wave velocities (VP) of 600, 1200, and 2100 m/sec were identified within an investigation depth of approximately 20 m. It was determined that the depths of the sliding surface changed between approximately 3 to 7 m and seismic velocities were lower than 600 m/sec from these depths to the surface. The geophysical results demonstrated that the landslide type was planar sliding, the sliding direction was S-SE, and the tilt of the geological layer was in the same direction with the topographic slope, mostly bigger than 50. It was observed that deformations in the landslide mass were caused by the geological unit, the layer or topographic slope, and precipitation. According to these results the landslide activity may continue in the landslide area and in the study area in the future. Therefore, as a result, it was also expressed that the study area contains the risks and the natural/anthropogenic hazards because the findings show that the settlement area and urban constructions are under threat in the west of Koyulhisar town center.
Abstract: The study area covers approximately 200x250 m2. This area is one of the most active locations with the greatest landslide displacement amount. This study aims to determine the depth of the sliding surface with geophysical (seismic refraction tomography (SRT) and ground-penetrating radar (GPR)) methods. The results of the TUBITAK-111Y111 project wer...
Show More
-
Second-order Central Difference Finite-difference Wave Equation Datuming Formulation
Issue:
Volume 11, Issue 5, October 2022
Pages:
289-306
Received:
13 June 2022
Accepted:
15 August 2022
Published:
8 October 2022
DOI:
10.11648/j.earth.20221105.16
Downloads:
Views:
Abstract: Several methods of referencing seismic reflection data to a new datum have been researched and presented in the literature, that differ in the approach used to implement the calculation of datumed wavefields. The implementation time determines, in part, the efficiency of such a method. In this paper, a simple finite-difference approach for extrapolating seismic data from one datum to another for seismic near-surface irregularity correction is derived. Kirchhoff’s integral forms the basis on which the formulation is based. The Kirchhoff summation method is used, in a novel way, in agreement with summation theory by considering a single trace as an input wavefield to the algorithm. The approach is considered time-saving in computing the output wavefields as only a single trace serves as an input in any occasion of producing every output trace. For prestack data, the method consists of two steps; calculating the wavefields referenced to the output datum for a source and receivers and time- shifting the resulting data along the mean travel-time ray paths. The algorithm is successfully applied to real data and synthetic shot gathers. For a horizontally layered earth model with a planar surface, mathematical analysis shows that the gradient of the locus of the reflection travel time increases with offset, for a shot-on-end reflection profiling, in conformity with the synthetic data obtained for such a model. In the said analysis, considering parabolic, hyperbolic, and nonhyperbolic travel-time approximations, the gradient forms a useful tool for normal moveout velocity determination. The implementation of the algorithm on field data samples suppressed coherent noise, including the long-wavelength type such as ground roll, in contrast with the static correction method. The normal moveout corrections show that shift along ray-path produced less normal moveout stretch than shift along vertical for near-surface events for the same normal moveout parameters.
Abstract: Several methods of referencing seismic reflection data to a new datum have been researched and presented in the literature, that differ in the approach used to implement the calculation of datumed wavefields. The implementation time determines, in part, the efficiency of such a method. In this paper, a simple finite-difference approach for extrapol...
Show More
-
Hydrogeochemical Processes of Groundwater from Basement Complex Rocks in Keffi, Central Nigeria
Aisha Abubakar Kana,
Abu Nasiru Enebi,
Ahmad Abubakar Kana
Issue:
Volume 11, Issue 5, October 2022
Pages:
307-315
Received:
23 March 2022
Accepted:
28 April 2022
Published:
24 October 2022
DOI:
10.11648/j.earth.20221105.17
Downloads:
Views:
Abstract: Hydrochemical study of groundwater was done in a typical Basement Complex terrain to identify geochemical evolution of the resource and possible quality issues. In addition to water samples, overburden and fresh rock samples were analyzed for major ion concentration. Relative abundance of these ions in groundwater was compared to their concentrations in the weathered and fresh rock. Conventional graphical plots (Gibbs, Piper, and ionic ratio plots) of ionic concentrations in the groundwater were used to characterize water Facies and identify major processes responsible for the ionic assemblage. The study area is underlain by two main rock types, schist and gneiss. Relative abundance of major cations in groundwater is in the order: Ca2+ > Mg2+ > Na+ > K+ while relative abundance of major anions is in the order: Cl- > HCO3- > CO32- > SO42-. In comparison, depletion in the concentration of calcium, magnesium and sodium was observed in the weathered zone while being enriched in the fresh rock. This indicates the possibility of the ions being leached by infiltrating/percolating groundwater. Physical parameters indicate that pH of groundwater ranges from 5.6 to 13.1; TDS is also high ranging from 146.10mg/l and 9146.00mg/l. The main water type identified is mixed Ca-Mg-Cl type; others are Na-Cl, mixed Ca-Na-HCO3, and Ca-HCO3 types. Results of the analysis indicate that the main sources of ions into the groundwater are from water rock interaction i.e. dissolution and leaching from silicate minerals in the study area. Ground water is a mixture of the multiple processes involved in its evolution but especially that mineralogy of the aquifers plays an important role in determining the water chemistry. Most sampling points were hand dug wells and boreholes for domestic use; the high TDS and alkalinity of the water therefore presents some quality concerns.
Abstract: Hydrochemical study of groundwater was done in a typical Basement Complex terrain to identify geochemical evolution of the resource and possible quality issues. In addition to water samples, overburden and fresh rock samples were analyzed for major ion concentration. Relative abundance of these ions in groundwater was compared to their concentratio...
Show More
-
Embankment Stability Assessment in the Mfilou District (Brazzaville-Congo)
Kempena Adolphe,
Watha Ndoudy Noël,
Obami Ondon Harmel,
Antonio Olimpio Gonçalves,
Rafael Guardado Lacaba,
Boudzoumou Florent
Issue:
Volume 11, Issue 5, October 2022
Pages:
316-326
Received:
2 August 2022
Accepted:
23 August 2022
Published:
24 October 2022
DOI:
10.11648/j.earth.20221105.18
Downloads:
Views:
Abstract: Embankment failure is a common problem in Congo Republic. Almost each year in northern part of Brazzaville City embankments are facing problems such as rupturing or landslides. Among several reasons the main causes are considered because of geologically unstable materials, inadequate method of building, seepage and sliding. The current study aims to evaluate the effect of load and influence of topographic parameters such as the gradient and height of the slope on the road embankment stability with sandy landfill in the Mfilou district, Brazzaville City (Congo republic). The evaluation of the road embankment slope stability and the discovery of the implications of topographic parameters on the embankment safety management were carried out in a hilly area. A database was created based on the site inventory from field studies complemented by experimental and desk investigation. The soils properties and values of topographic parameters were incorporated to the embankment slope model as well. So, the slope modelling was carried out in different scenarios such as different slope heights, different slope angles with and without load effect. Then embankment stability was analysed with Slide 6.0 software finding slip surfaces from limit equilibrium methods. Results showed that despite the slope instability caused by the load effect, but the variation of topographic parameters affects the embankment stability as well.
Abstract: Embankment failure is a common problem in Congo Republic. Almost each year in northern part of Brazzaville City embankments are facing problems such as rupturing or landslides. Among several reasons the main causes are considered because of geologically unstable materials, inadequate method of building, seepage and sliding. The current study aims t...
Show More
-
Analysis of the Values of Ground Displacements, Shear Strains, Velocities and Accelerations, and Response Spectra of Strong Earthquake by Synthetic Accelerograms
Issue:
Volume 11, Issue 5, October 2022
Pages:
327-337
Received:
18 September 2022
Accepted:
4 October 2022
Published:
24 October 2022
DOI:
10.11648/j.earth.20221105.19
Downloads:
Views:
Abstract: In previously published works of the author, a mechanical-mathematical method has been developed for modelling strong earthquake synthetic seismograms and accelerograms for a given site with certain ground conditions, whereby an earthquake is viewed as an effect of instant rupturing of Earth’s crust. This study examines ground displacements, velocities, accelerations, and relative shear strains, as well as earthquake response spectra based on synthetic accelerograms. All ground categories are reviewed, from the hardest rocks to the loosest grounds. The maximum values for ground displacements, velocities, and accelerations are obtained depending on the attenuation coefficient of the rocks and the number of the considered foundation bedding’s oscillation modes, as well as peak ground accelerations depending on the distance from the expected earthquake’s rupture. It is shown that the higher modes of oscillation increase ground acceleration 2.5 times, if calculated only using the first oscillation mode and they also increase ground displacements 1.1 times, while decreasing shear strain 1.1 times. The maximum positive attenuation effect in hard ground compared to its absence reaches 37%. Shear strain values increase proportionally to the increase of soil category order number. At the level of 15 meters from Earth’s surface in rocky soils, at a magnitude of М=7.0, the shear strain values exceed the critical thresholds, which implies a high probability of surface rupturing, Response spectra obtained by synthetic accelerograms are compared to similar spectra based on a large number of actual earthquakes, showing that they are quite similar both in qualitative and quantitative terms. Based on the obtained results, it is recommended to use them for assessing the seismic hazard levels at various areas, monitoring for earthquake prediction, ensuring seismic safety of facilities and underground structures, and enhancing the analysis methods of seismic impact on building and structures.
Abstract: In previously published works of the author, a mechanical-mathematical method has been developed for modelling strong earthquake synthetic seismograms and accelerograms for a given site with certain ground conditions, whereby an earthquake is viewed as an effect of instant rupturing of Earth’s crust. This study examines ground displacements, veloci...
Show More
