scholarly journals Geophysical Data Processing for the Delineation of Tectonic Lineaments in South Cameroon

2019 ◽  
Vol 8 (2) ◽  
pp. 1
Author(s):  
Quentin Marc Anaba Fotze ◽  
Charles Antoine Basseka ◽  
Anatole Eugene Djieto Lordon ◽  
Albert Eyike Yomba ◽  
Yves Shandini ◽  
...  
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
Structural Features ◽  
Horizontal Gradient ◽  
Tectonic Event ◽  
Structural Framework ◽  
Pan African ◽  
Eburnean Orogeny ◽  
Tilt Derivative ◽  
Total Horizontal Derivative

The processing of aeromagnetic and gravity data of the Northern part of Congo Craton (South Cameroon region), between latitudes 2°30’-3°30’ N and longitudes 12°-13° E, permitted the determination of the structural features ccurring within the Precambrian basement (Ntem Complex) southwards and the Pan-African belt (Yaounde Group) northwards. The maxima of the Horizontal Gradient within the study area, were obtained using the Blakely and Simpson method (1986). Those maxima were used to trace the magnetic lineaments of the study area. Furthermore, the Total Horizontal derivative of the Tilt derivative applied on the residual grid of Bouguer anomaly guaranteed the enhancement of linear structures which were automatically extracted using the CET Grid Analysis algorithm. The superimposition of both magnetic and gravity lineaments allowed us to display the structural framework of the area, whose major trending directions are E-W, ENE-WSW, and NE-SW. These major lineament directions are likely to be linked to one or more than a single tectonic event such as the ENE-WSW/NE-SW trends, considered as the subduction direction of the Congo craton beneath the Pan-African belt. These trends may be linked to the Eburnean orogeny and are also said to be connected to the Central African Shear Zone (CASZ). The geophysical lineaments identified in the study are defined as potential targets along which mineralization may have been formed, considering the economic potential of the area.

scholarly journals Exploiting Aeromagnetic and Gravity Data Interpretation to Delineate Massif Deposits of Rehamna Area (Western Meseta-Morocco)

2021 ◽  
Vol 54 (2C) ◽  
pp. 13-28
Author(s):  
Kawtar Benyas
Keyword(s):  
Gravity Data ◽  
Precious Metals ◽  
Data Interpretation ◽  
Structural Features ◽  
Magnetic Data ◽  
Gravity Gradient ◽  
Horizontal Gradient ◽  
Geological Structures ◽  
Magnetic Signatures ◽  
First Vertical Derivative

The analysis of the magnetic signatures and gravity gradient values of the Rehamna Massif south of the Moroccan Western Meseta by using Geosoft Oasis Montaj 7.0.1 software, allowed us to detect several useful anomalies to be exploited and which are related to magmatic bodies and structural features within the study area. These data were analyzed by applying several techniques, including the horizontal gradient filters combined with the first vertical derivative. Subsurface structures; such as geological boundaries, faults, dykes and folds, were visualized as lineaments on geophysical maps, then results were compared with structural features provided by previous studies in the region. Thus, the Rehamna Massif structural map shows sets of linear features which may represent faults or boundaries of geological structures, which can be either faults or boundaries of geological structures, and they are mostly oriented in the directions: N-S, NNE-SSW, NE-SW, E-W with the predominance of the NNE-SSW to NE-SW directions. In addition, the super position of the minerals bearing beds or formations were distinguished from gravity and magnetic data processing results. Some of the recognized anomalies are related to the existence of precious metals which belong to the granitic bodies within the study area.

scholarly journals Tectonic and Hydrothermal Activities in Debagh, Guelma Basin (Algeria)

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Said Maouche ◽  
Abdeslam Abtout ◽  
Nacer-Eddine Merabet ◽  
Tahar Aïfa ◽  
Atmane Lamali ◽  
...  
Keyword(s):  
Field Study ◽  
Active Fault ◽  
Hot Springs ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Hydrothermal Activity ◽  
Structural Features ◽  
Tectonic Activity ◽  
Hydrothermal Activities ◽  
Field Geology

Quaternary and Pliocene travertines, deposited from hot springs, can reveal much about neotectonic and hydrothermal activity. The aim of this work is the understanding of the actual tectonic activity in the Guelma Basin and in one of its spa structures. Gravity data were collected during a field study in the Hammam Debagh (HD) area and then analyzed to better highlight the architecture of its subsurface underlying structures. This analysis was performed by means of a Bouguer anomaly, upward continuations, and residual and derivative maps. Comparison of gravity maps, field geology, geomorphic observations, and structural maps allowed us to identify the major structural features in the Hammam Debagh. As a result, we confirm the position of the Hammam Debagh active fault which is superimposed to the hydrothermal active source in the NW-SE direction characterized by a negative gravity anomaly.

scholarly journals Evidence of Major Structural Features over the Pan-African Domain in the Bertoua-Mbangue Area (East Cameroon) from a Multiscale Approach of Modeling and Interpretation of Aeromagnetic Data

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Owono Amougou Olivier Ulrich Igor ◽  
Ndougsa Mbarga Theophile ◽  
Meying Arsène ◽  
Assembe Stephane Patrick ◽  
Ngoh Jean Daniel ◽  
...  
Keyword(s):  
High Amplitude ◽  
Structural Features ◽  
Short Wave ◽  
The Other ◽  
Horizontal Gradient ◽  
Multiscale Approach ◽  
Magnetic Intensity ◽  
Aeromagnetic Data ◽  
Pan African ◽  
Basement Structures

The aim of this study is to investigate crustal structures from East Cameroon, using aeromagnetic data. The modeling of aeromagnetic data is conducted using the Oasis Montaj 8.0 software. The total magnetic intensity map reduced to the equator (RTE-TMI) shows important anomalies features, namely, the Northern East magnetic anomalies of high amplitude, the Southwest where very low values of the magnetic intensity were observed, and a corridor with negative values relatively high, separating the anomalies. The horizontal gradient map shows on the one hand brittle and folded structures carried out in the area of study and on the other hand various rectilinear, narrow, and short-wave anomalies that can be classified as a family of little faults. The maxima observed on the RTE-TMI maps are correlated to intrabasement contacts; and the map derived from Euler’s solutions permitted to evaluate the depth of the geological accidents observed from the other filters. This map also reveals new faults with a depth greater than 5000 m. The lineaments identified in the Southwestern part could be linked to the Pan-African orogeny and seem to correspond to deep-seated basement structures, which are referred to the tectonic boundary between Congo Craton and the Pan-African orogeny belt. A 23/4-D modeling confirmed the observations derived from the RTE-TMI and HGM maps analyses. It shows intrusive bodies composed of gneiss and porphyroid granite and some domes with their roof situated at various depths not exceeding 1800 m from the surface. The structural map of the study area shows the trending of the structural features observed, namely, NE-SW, NW-SE, ENE-WSW, and WNW-ESE, respectively, while the E-W and N-S are secondary orientation of the observed tectonic evidence. Moreover, circular anomalies observed over the area are assimilated to intrusions of high magnetic materials or to granitic domes.

scholarly journals Combination of Terrestrial and Satellite Gravity Data for the Characterization of the Southwestern Coastal Region of Cameroon: Appraisal for Hydrocarbon Exploration

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Paul Gautier Kamto ◽  
Willy Lemotio ◽  
Alain-Pierre Kamga Tokam ◽  
Loudi Yap
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
Coastal Region ◽  
Hydrocarbon Exploration ◽  
Horizontal Gradient ◽  
Target Area ◽  
Satellite Gravity ◽  
Area Of Interest ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

The southwestern coastal region of Cameroon is an area of interest because of its hydrocarbon potential (gas and oil). Terrestrial and satellite gravity data were combined and analyzed to provide a better precision in determining the structure of the study area. Firstly, the two gravity databases (in situ and satellite) have been coupled and validated using the least square collocation technique. Then, spectral analysis was applied to the combined Bouguer anomaly map to evaluate the thickness of sediments in some localities. We found that the sedimentary cover of the southwestern coastal region of Cameroon has a thickness that varies laterally from 1.68 ± 0.08 to 2.95 ± 0.15   km , especially in the western part. This result confirms that our target area is a potential site for hydrocarbon exploration. The horizontal gradient method coupled with the upward continuation at variable heights has been used to highlight several lineaments and their directions (N-S, E-W, SW-NE, and SSW-NNE). Lineaments trending in an N-S orientation are predominant. The Euler deconvolution method was also applied to the Bouguer anomaly map to determine the position, orientation, and depth of the different superficial faults of the study area. It appears that the majority of superficial faults have an N-S and SSW-NNE orientation. These directions are correlated with those previously highlighted by the maxima of horizontal gradient. The structural map could be used for a better identification of the direction of fluid flow within the subsurface or to update the geological map of our study area.

scholarly journals Gravity Analysis for Subsurface Characterization and Depth Estimation of Muda River Basin, Kedah, Peninsular Malaysia

2021 ◽  
Vol 11 (14) ◽  
pp. 6363
Author(s):  
Muhammad Noor Amin Zakariah ◽  
Norsyafina Roslan ◽  
Norasiah Sulaiman ◽  
Sean Cheong Heng Lee ◽  
Umar Hamzah ◽  
...  
Keyword(s):  
River Basin ◽  
Rock Type ◽  
Gravity Data ◽  
Power Spectral Analysis ◽  
Depth Estimation ◽  
Structural Features ◽  
Peninsular Malaysia ◽  
Gravity Survey ◽  
Basement Rock ◽  
Geophysical Techniques

Gravity survey is one of the passive geophysical techniques commonly used to delineate geological formations, especially in determining basement rock and the overlying deposit. Geologically, the study area is made up of thick quaternary alluvium deposited on top of the older basement rock. The Muda River basin constitutes, approximately, of more than 300 m of thick quaternary alluvium overlying the unknown basement rock type. Previous studies, including drilling and geo-electrical resistivity surveys, were conducted in the area but none of them managed to conclusively determine the basement rock type and depth precisely. Hence, a regional gravity survey was conducted to determine the thickness of the quaternary sediments prior to assessing the sustainability of the Muda River basin. Gravity readings were made at 347 gravity stations spaced at 3–5 km intervals using Scintrex CG-3 covering an area and a perimeter of 9000 km2 and 730 km, respectively. The gravity data were then conventionally reduced for drift, free air, latitude, Bouguer, and terrain corrections. These data were then consequently analyzed to generate Bouguer, regional and total horizontal derivative (THD) anomaly maps for qualitative and quantitative interpretations. The Bouguer gravity anomaly map shows low gravity values in the north-eastern part of the study area interpreted as representing the Main Range granitic body, while relatively higher gravity values observed in the south-western part are interpreted as representing sedimentary rocks of Semanggol and Mahang formations. Patterns observed in the THD anomaly and Euler deconvolution maps closely resembled the presence of structural features such as fault lineaments dominantly trending along NW-SE and NE-SW like the trends of topographic lineaments in the study area. Based on power spectral analysis of the gravity data, the average depth of shallow body, representing alluvium, and deep body, representing underlying rock formations, are 0.5 km and 1.2 km, respectively. The thickness of Quaternary sediment and the depth of sedimentary formation can be more precisely estimated by other geophysical techniques such as the seismic reflection survey.

The Structural Framework of Pictorial Balance

Perception ◽  
1996 ◽  
Vol 25 (12) ◽  
pp. 1419-1436 ◽  
Author(s):  
Paul Locher ◽  
Sharon Gray ◽  
Calvin Nodine
Keyword(s):  
Visual Arts ◽  
Structural Features ◽  
Original Compositions ◽  
The Other ◽  
Global Integration ◽  
Artistic Style ◽  
Structural Framework ◽  
Museum Professionals ◽  
Balance Structure ◽  
Good Agreement

Two experiments were performed to examine how the subjective balance of a painting is created by its structural features and to determine if balance influences the way people look at paintings. Stimuli consisted of sixteen reproductions of twentieth-century paintings varying in artistic style and a reconstructed less-balanced version of each. Participants in experiment 1 determined the location of the balance center of each composition, assigned ‘weights’ to the pictorial features which contributed to the location of the balance center, and rated the picture for balance. It was found that design and museum professionals and individuals untrained in the visual arts were in good agreement as to the structural framework underlying the balance organization of a painting. For all participants, disruption of the balanced organizations of the original compositions led to reliable shifts in the location of the perceived balance centers of the originals compared with their less-balanced perturbations. Additionally, it was observed that particular features as such were not the origin of the balance phenomenon; rather, judgments concerning the balance structure and its center were dependent on the global integration of information across a wide area of the display field, but especially from its central region. Last, the subtle changes in balance structure between versions resulted in lower ratings of balance being assigned to the less-balanced perturbations by the design professionals only; the other two participant groups evaluated overall balance of the versions as comparable. In experiment 2, eye movements of a different group of untrained individuals were recorded as they performed similar tasks on the art stimuli. It was found that disruption of the balance structure of the original representational but not abstract compositions resulted in different regions of the original and perturbed versions being visually explored. Findings of both experiments are related to theoretical notions of balance.

New insights into the Hercynian Orogeny, and their implications for the Paleozoic Hydrocarbon System in the Arabian Plate

GeoArabia ◽  
2009 ◽  
Vol 14 (3) ◽  
pp. 199-228 ◽  
Author(s):  
Mohammad Faqira ◽  
Martin Rademakers ◽  
AbdulKader M. Afifi
Keyword(s):  
Oil And Gas ◽  
Seismic Imaging ◽  
Structural Features ◽  
Source Rocks ◽  
Arabian Plate ◽  
Arabian Shield ◽  
Tectonic Event ◽  
Angular Unconformity ◽  
The North ◽  
Hercynian Orogeny

ABSTRACT During the past decade, considerable improvements in the seismic imaging of the deeper Paleozoic section, along with data from new well penetrations, have significantly improved our understanding of the mid-Carboniferous deformational event. Because it occurred at the same time as the Hercynian Orogeny in Europe, North Africa and North America it has been commonly referred to by the same name in the Middle East. This was the main tectonic event during the late Paleozoic, which initiated or reactivated many of the N-trending block uplifts that underlie the major hydrocarbon accumulations in eastern Arabia. The nature of the Hercynian deformation away from these structural features was poorly understood due to inadequate seismic imaging and insufficient well control, along with the tectonic overprint of subsequent deformation events. Three Hercynian NE-trending arches are recognized in the Arabian Plate (1) the Levant Arch, which extended from Egypt to Turkey along the coast of the Mediterranean Sea, (2) the Al-Batin Arch, which extended from the Arabian Shield through Kuwait to Iran, and (3) the Oman-Hadhramaut Arch, which extended along the southeast coast of Oman and Yemen. These arches were initiated during the mid-Carboniferous Hercynian Orogeny, and persisted until they were covered unconformably by the Khuff Formation during the Late Permian. Two Hercynian basins separate these arches: the Nafud-Ma’aniya Basin in the north and Faydah-Jafurah Basin in the south. The pre-Hercynian Paleozoic section was extensively eroded over the arches, resulting in a major angular unconformity, but generally preserved within the basins. Our interpretation suggests that most of the Arabian Shield, except the western highlands along the Red Sea, is the exhumed part of the Al-Batin Arch. The Hercynian structural fabric of regional arches and basins continue in northern Africa, and in general appear to be oriented orthogonal to the old margin of the Gondwana continent. The Hercynian structure of arches and basins was partly obliterated by subsequent Mesozoic and Cenozoic tectonic events. In eastern Saudi Arabia, Qatar, and Kuwait, regional extension during the Triassic formed N-trending horsts and graben that cut across the NE-trending Hercynian mega-structures, which locally inverted them. Subsequent reactivation during the Cretaceous and Neogene resulted in additional growth of the N-trending structures. The Hercynian Arches had major impact on the Paleozoic hydrocarbon accumulations. The Silurian source rocks are generally preserved in the basins and eroded over the arches, which generally confined Silurian-sourced hydrocarbons either within the basins or along their flanks. Furthermore, the relict Hercynian paleo-topography generally confined the post-Hercynian continental clastics of the Unayzah Formation and equivalents to the Hercynian basins. These clastics contain the main Paleozoic oil and gas reservoirs, particularly along the basin margins where they overlie the sub-crop of the Silurian section with angular unconformity, thus juxtaposing reservoir and source rock.

scholarly journals Geometrical Characterisation of the Mamfe Basin, Cameroon, from the Earth, Gravitational Model (EGM 2008)

2018 ◽  
Vol 7 (1) ◽  
pp. 94
Author(s):  
Anatole Eugene Djieto Lordon ◽  
Mbohlieu YOSSA ◽  
Christopher M Agyingi ◽  
Yves Shandini ◽  
Thierry Stephane Kuisseu
Keyword(s):  
Average Length ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Igneous Rocks ◽  
Average Depth ◽  
The Earth ◽  
Gravitational Model ◽  
Petroleum Generation ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

Gravimetric studies using the ETOPO1-corrected high resolution satellite-based EGM2008 gravity data was used to define the surface extent, depth to basement and shape of the Mamfe basin. The Bouguer anomaly map was produced in Surfer 11.0. The Fast Fourier Transformed data was analyzed by spectral analysis to remove the effect of the regional bodies in the study area. The residual anomaly map obtained was compared with the known geology of the study area, and this showed that the gravity highs correspond to the metamorphic and igneous rocks while the gravity lows match with Cretaceous sediments. Three profiles were drawn on the residual anomaly map along which 2D models of the Mamfe basin were drawn. The modeling was completed in Grav2dc v2.06 software which uses the Talwini’s algorithm and the resulting models gave the depth to basement and the shape of the basement along the profiles. After processing and interpretation, it was deduced that the Mamfe basin has an average length and width of 77.6 km and 29.2 km respectively, an average depth to basement of 5 km and an overall U-shape basement. These dimensions (especially the depth) theoretically create the depth and temperature conditions for petroleum generation. 

scholarly journals Lineament Extraction using Gravity Data in the Citarum Watershed

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Gumilar Utamas Nugraha ◽  
Karit Lumban Goal ◽  
Lina Handayani ◽  
Rachmat Fajar Lubis
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
High Density ◽  
Low Density ◽  
Residual Value ◽  
Satellite Gravity ◽  
Structural Weakness ◽  
Major Trend ◽  
Lineament Extraction ◽  
Butterworth Filters

Lineament is one of the most important features showing subsurface elements or structural weakness such as faults. This study aims to identify subsurface lineament patterns using automatic lineament in Citarum watershed with gravity data. Satellite gravity data were used to generate a sub-surface lineament. Satellite gravity data corrected using Bouguer and terrain correction to obtain a complete Bouguer anomaly value. Butterworth filters were used to separate regional and residual anomaly from the complete Bouguer anomaly value. Residual anomaly gravity data used to analyze sub-surface lineament. Lineament generated using Line module in PCI Geomatica to obtain sub-surface lineament from gravity residual value. The orientations of lineaments and fault lines were created by using rose diagrams. The main trends observed in the lineament map could be recognized in these diagrams, showing a strongly major trend in NW-SE, and the subdominant directions were in N-S. Area with a high density of lineament located at the Southern part of the study area. High-density lineament might be correlated with fractured volcanic rock upstream of the Citarum watershed, meanwhile, low-density lineament is associated with low-density sediment. The high-density fracture might be associated with intensive tectonics and volcanism.

Sign in / Sign up

Export Citation Format

Share Document