scholarly journals Structural Interpretation of Lineament from Nlonako Area and Surroundings: Contribution to Pan-African Tectonic Reconstruction

2020 ◽  
Vol 1 (5) ◽  
Author(s):  
Julie Agathe Noudiedie Kamgang ◽  
Jules Tcheumenak Kouémo ◽  
Eric Martial Fozing ◽  
Dongmo Armand Kagou ◽  
Roslin Brice Kenfack
Keyword(s):  
Shear Zone ◽  
Geological Mapping ◽  
Landsat 8 ◽  
Basement Rock ◽  
Tectonic History ◽  
Pan African ◽  
Anticlockwise Rotation ◽  
Tectonic Reconstruction ◽  
Ring Complex ◽  
Lineament Analysis

The Nlonako anorogenic complex (NAC) is located in the south western part of the Cameroon Line and is superposed on the N50E section of the central Cameroon shear zone. It is suggested to be a ring complex of 10 km diameter which was emplaced as sill intrusive body during the Tertiary. In order to do characterize the Nlonako complex shape and characterize the tectonic history in the study area and surrounding, spatial technology (Landsat 8 ETM+ and SRTM images) were used for geological mapping and structural reconstruction based on lineament analysis. Data extracted from Landsat 8 ETM and SRTM images show a sub-circular shape for the NAC and the superposition of field and petrographic data from our previous research works confirm the fact that the NAC is a ring or annular complex slightly elongated NNE-SSW, thus it is known as the Nlonako ring complex (NRC). Map of lineament synthesis and the SRTM image of the study area display NE-SW, NW-SE and N-S trend structures. (1) The dominant NE-SW trend mostly displayed by the NRC and its basement rock is parallel to (i) the main metamorphic foliation trend and (ii) to the central Cameroon shear zone regional fault, corresponds to the trending of the regional foliation, structures and the Ngondo pluton elongated shape. (2) The secondary N-S direction may correspond to the late deformational phase in the area because, the N-S-related structures transposing NE-SW structures towards a meridional direction in the NRC basement rock. (3) The NW-SE trend corresponds to the direction of NW-SE fault cross cutting the NRC. Field data and synthetic lineament map enable to identify: (1) a Compressive deformational phase D1 whose main markers are NNW-SSE to NW-SE S1 foliation; (2) an early left-lateral deformational phase D2 characterized by anticlockwise rotation of clasts and NE-SW sinistral transposition of early structures; (3) a NE-SW right-lateral deformational phase D3 marked by clockwise rotation and dextral transposition of preexisting structures as well as the NE-SW S3 foliation and (4) a late left-lateral deformational phase D4 marked by the N-S transposition of NE-SW dextral D3-related structures by late sinistral shear movement. This suggests a more complex tectonic history for the Pan-African Belt in Cameroon showing at least three shear phases, that is a right-lateral phase, sandwich by two left-lateral phases.  

scholarly journals Lineament automatic extraction analysis for Galal Badra river basin using Landsat 8 satellite image

2019 ◽  
Vol 12 (25) ◽  
pp. 44-55 ◽  
Author(s):  
Safaa Sabah Adhab
Keyword(s):  
Program Analysis ◽  
Satellite Image ◽  
Landsat 8 ◽  
Automatic Extraction ◽  
Lineament Density ◽  
Density Analysis ◽  
Lineament Analysis ◽  
Intersection Density ◽  
Surrounding Areas ◽  
The Relationship

This research including lineament automated extraction by using PCI Geomatica program, depending on satellite image and lineament analysis by using GIS program. Analysis included density analysis, length density analysis and intersection density analysis. When calculate the slope map for the study area, found the relationship between the slope and lineament density.The lineament density increases in the regions that have high values for the slope, show that lineament play an important role in the classification process as it isolates the class for the other were observed in Iranian territory, clearly, also show that one of the lineament hit shoulders of Galal Badra dam and the surrounding areas dam. So should take into consideration the lineaments because its plays an important role in the study area.

Outline of the geochronology and tectonic units of the basement complex of northeast Africa

1976 ◽  
Vol 350 (1660) ◽  
pp. 127-141 ◽  
Keyword(s):  
Regional Metamorphism ◽  
Central Africa ◽  
Geological Mapping ◽  
Fold Belt ◽  
Basement Complex ◽  
Southern Sudan ◽  
Pan African ◽  
Mozambique Belt ◽  
Unknown Area ◽  
Eastern Uganda

Results of new geological mapping with the help of air and satellite photo­graphy in Sudan together with information from adjacent territories has enabled a map to be drawn showing the dominant basement tectonic trends in a previously geologically unknown area. Over 100 age deter­minations, including 25 unpublished analyses, allow the recognition of Eburnian age events in Central Africa Republic and southeast Libya similar to the 1950 million year (Ma) old Ruwenzori Belt in Uganda and similar events in Zaire. A northeast trending fold belt is recognized in Central Africa, western Sudan and southeast Egypt in which 1000 Ma ages are found. The Pan African age Mozambique belt truncates older structures in eastern Uganda and southern Sudan but is covered by a greenschist volcanic assemblage along the Red Sea coast in which 550 ± 150 Ma old granites and regional metamorphism occur.

scholarly journals The Main Shear Zone in Sør Rondane, East Antarctica: Implications for the late-Pan-African tectonic evolution of Dronning Maud Land

Tectonics ◽  
2015 ◽  
Vol 34 (6) ◽  
pp. 1290-1305 ◽  
Author(s):  
Antonia S. Ruppel ◽  
Andreas Läufer ◽  
Joachim Jacobs ◽  
Marlina Elburg ◽  
Nicole Krohne ◽  
...  
Keyword(s):  
Shear Zone ◽  
Tectonic Evolution ◽  
East Antarctica ◽  
Pan African ◽  
Dronning Maud Land

scholarly journals Electrical resistivity structure of the Great Slave Lake shear zone, northwest Canada: implications for tectonic history

2014 ◽  
Vol 199 (1) ◽  
pp. 178-199 ◽  
Author(s):  
Yaotian Yin ◽  
Martyn Unsworth ◽  
Mitch Liddell ◽  
Dinu Pana ◽  
James A. Craven
Keyword(s):  
Electrical Resistivity ◽  
Shear Zone ◽  
Resistivity Structure ◽  
Tectonic History ◽  
Great Slave Lake

First report of Pan-African Sm—Nd and Rb—Sr mineral isochron ages from regional charnockites of southern India

1995 ◽  
Vol 132 (3) ◽  
pp. 253-260 ◽  
Author(s):  
C. Unnikrishnan-Warrier ◽  
M. Santosh ◽  
M. Yoshida
Keyword(s):  
Sri Lanka ◽  
Shear Zone ◽  
East Antarctica ◽  
Southern India ◽  
Peninsular India ◽  
Pan African ◽  
Mineral Isochron ◽  
Nd Model Age ◽  
Tectonothermal Event ◽  
Good Agreement

AbstractMineral and whole-rock isotope data for a massive charnockite from Kottaram in the Nagercoil Block at the southern tip of Peninsular India yield Sm—Nd and Rb—Sr ages of 517 ± 26 Ma and 484 ± 15 Ma respectively. The Nd model age calculated for the charnockite is c. 2100 Ma. Our study reports the first Pan-African mineral isochron ages from regional charnockites of Peninsular India, which are in good agreement with the recently obtained ages of incipient charnockites in the adjacent blocks, as well as alkaline plutons within the same block. Our results indicate that the Pan-African tectonothermal event in the granulite blocks south of the Palghat—Cauvery shear zone was regional, with terrain-wide rejuvenation. These results correlate with similar Pan-African tectono-thermal events reported from Sri Lanka and East Antarctica, and have an important bearing on Gondwana reconstructions.

Pan-African charnockite formation in Kerala, South India

1992 ◽  
Vol 129 (3) ◽  
pp. 257-264 ◽  
Author(s):  
A. K. Choudhary ◽  
N. B. W. Harris ◽  
P. van Calsteren ◽  
C. J. Hawkesworth
Keyword(s):  
Sri Lanka ◽  
Shear Zone ◽  
South India ◽  
Metamorphic Event ◽  
Isotopic Ratios ◽  
Sr Isotope ◽  
Pan African ◽  
Granulite Metamorphism ◽  
History Of

AbstractSm-Nd mineral ages of gneisses and associated granulites from the Ponmudi incipient charnockite locality (South India) indicate that granulite metamorphism occurred at, or shortly after, 558 Ma. Proterozoic ages recorded by garnet separates reflect a detrital age or an earlier metamorphic event preserved by inclusions within garnet. The age of post-metamorphic uplift (440–460 Ma) is constrained by Sr isotope equilibration between biotite and plagioclase. Since charnockite formation and subsequent uplift north of the Palghat-Cauvery shear zone had terminated by earliest Proterozoic time, these results confirm two distinct periods of granulite formation in South India and suggest that the Palghat-Cauvery shear zone represents the boundary between two blocks of strongly contrasting geological histories. Both incipient charnockite formation and subsequent uplift at Ponmudi may be correlated with the tectonothermal evolution of the Highlands Group in Sri Lanka. The similarity between Nd and Sr model ages for charnockites and gneisses from Ponmudi indicates that no significant Rb-Sr fractionation has occurred during the crustal history of these incipient charnockites. Pb isotopic ratios suggest that Th-U ratios were fractionated during charnockite formation at about 500 Ma. In contrast to charnockites found north of the Palghat-Cauvery shear zone, fractionation of U-Pb during the Archaean did not occur in the Ponmudi granulites.

scholarly journals Geological mapping and mineral prospectivity using remote sensing and GIS in parts of Hamissana, Northeast Sudan

2021 ◽  
Vol 11 (3) ◽  
pp. 1123-1138
Author(s):  
Mohamed Taha AlMakki Mohamed ◽  
Latifa Shaheen Al-Naimi ◽  
Tochukwu Innocent Mgbeojedo ◽  
Chidiebere Charles Agoha
Keyword(s):  
Remote Sensing ◽  
Gold Mineralization ◽  
Principal Component ◽  
Original Data ◽  
Wall Rock ◽  
Geological Mapping ◽  
Landsat 8 ◽  
Alteration Zones ◽  
Wall Rock Alteration ◽  
Rock Alteration

AbstractIn recent years, various geological activities and different mineral prospecting and exploration programs have been intensified along the Red Sea hills in order to elucidate the geological maps and to evaluate the mineral potentials. This study is therefore aimed at testing the viability of using remote sensing and geographic information system (GIS) techniques for geological mapping and prospecting for gold mineralization in the area. The study area is located in northeast Sudan and covers an area of about 1379 km2. Different digital image processing techniques were applied to Landsat 8 Operational Land Imager image in order to increase the discrimination between various lithological units and to delineate wall rock alteration which represents target zones for gold mineralization. Image sharpening was performed to enhance the spatial resolution of the images for more detailed information. Contrast stretching was applied after the various digital processing procedures to produce more interpretable images. The principal component analysis transformations yielded saturated images and resulted in more interpretable images than the original data. Several ratio images were prepared, combined together and displayed in RGB color composite ratio images. This process revealed the existence of alteration zones in the study area. These zones extend from the northeast to the southwest in the acid meta-volcanic and silica barite rocks. The enhanced satellite images were implemented in the GIS environment to facilitate the final production of the geological map at scale 1:400,000. X-ray fluorescence analyses prove that selected samples taken from the wall rock alteration zones are gold-bearing.

scholarly journals Two decades of dynamic change and progressive destabilization on the Thwaites Eastern Ice Shelf

2021 ◽  
Vol 15 (11) ◽  
pp. 5187-5203
Author(s):  
Karen E. Alley ◽  
Christian T. Wild ◽  
Adrian Luckman ◽  
Ted A. Scambos ◽  
Martin Truffer ◽  
...  
Keyword(s):  
Shear Zone ◽  
Structural Integrity ◽  
Dynamic Change ◽  
Image Data ◽  
Landsat 8 ◽  
Ice Shelf ◽  
Ice Flow ◽  
Landsat 7 ◽  
Rapid Pace ◽  
Elevation Model

Abstract. The Thwaites Eastern Ice Shelf (TEIS) buttresses the eastern grounded portion of Thwaites Glacier through contact with a pinning point at its seaward limit. Loss of this ice shelf will promote further acceleration of Thwaites Glacier. Understanding the dynamic controls and structural integrity of the TEIS is therefore important to estimating Thwaites' future sea-level contribution. We present a ∼ 20-year record of change on the TEIS that reveals the dynamic controls governing the ice shelf's past behaviour and ongoing evolution. We derived ice velocities from MODIS and Sentinel-1 image data using feature tracking and speckle tracking, respectively, and we combined these records with ITS_LIVE and GOLIVE velocity products from Landsat-7 and Landsat-8. In addition, we estimated surface lowering and basal melt rates using the Reference Elevation Model of Antarctica (REMA) DEM in comparison to ICESat and ICESat-2 altimetry. Early in the record, TEIS flow dynamics were strongly controlled by the neighbouring Thwaites Western Ice Tongue (TWIT). Flow patterns on the TEIS changed following the disintegration of the TWIT around 2008, with a new divergence in ice flow developing around the pinning point at its seaward limit. Simultaneously, the TEIS developed new rifting that extends from the shear zone upstream of the ice rise and increased strain concentration within this shear zone. As these horizontal changes occurred, sustained thinning driven by basal melt reduced ice thickness, particularly near the grounding line and in the shear zone area upstream of the pinning point. This evidence of weakening at a rapid pace suggests that the TEIS is likely to fully destabilize in the next few decades, leading to further acceleration of Thwaites Glacier.

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