Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia

Muluken Fanta Bassa

doi:doi:10.11648/j.ijema.20200805.12

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Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia

Muluken Fanta Bassa

Published in International Journal of Environmental Monitoring and Analysis (Volume 8, Issue 5)

Received: 10 March 2020 Accepted: 25 May 2020 Published: 21 September 2020

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Abstract

The deformation history of Sorobo, Konso area (southern Ethiopia) within the Mozambique Belt, is described using microstructural and petrographic analysis. The area is characterized by folds and metamorphic fabrics that trend between NNE and NNW and consist of high-grade, amphibolite- to granulite-facies rocks. It is affected by five deformational phases (D1 to D5) and two metamorphic events (M1 & M2). During shortening deformation events (D1 to D3) the development of gneissosity (D1), the formation of tight to isoclinal and recumbent folds (D2) and the superposition of secondary (upright) fold (D3) on earlier recumbent fold resulting in type-3-fold interference pattern are formed respectively. During fourth deformation phase (D4) most of the rock units of the area are affected by shearing or shows east and west vergence. The area is affected by both sinistral and a dextral sense of shearing but dextral shear-sense appears dominant. Brittle type of deformation phase (D5) was developed and resulting in different types of faults varies in orientation. Peak progressive metamorphism of the granulite facies (M1) and retrogression (M2) are also associated with the deformational phase. An equal-area plot and rose diagram shows the orientation of all fabric, which indicates multiphase deformation. Geological structures in the study areas like faults, joints & fissures, shear zones and folds are important depositional sites for different hydrothermal economic mineral deposits.

Published in	International Journal of Environmental Monitoring and Analysis (Volume 8, Issue 5)
DOI	10.11648/j.ijema.20200805.12
Page(s)	130-143
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2020. Published by Science Publishing Group

Keywords

Microstructure, Deformation, Metamorphism, Progression, Retrogression

References

[1]	Asrat, A. and Barbey, P. (2003). Petrology, geochronology and Sr–Nd isotopic geochemistry of the Konso pluton, south-western Ethiopia: implications for transition from convergence to extension in the Mozambique Belt, International Journal of Earth science (GeolRundsch), 92, pp. 873-890.
[2]	Asrat, A., Gleizes, G., Barbey, P. and Ayalew, D. (2003). Magma emplacement and mafic-felsic magma hybridization: structural evidence from the Pan-African Negash pluton, Northern Ethiopia. J Struct Geol 25, pp. 1451–1469.
[3]	Davidson, A. (1983). The Omo River Project, Reconnaissance geology and geochemistry of parts of Ilubabor, Kefa, Gemu Gofa and Sidamo, Ethiopia, Ethiopian Institute of Geological Surveys, Bulletin 2, Addis Ababa, pp. 18-42.
[4]	Ethiopian Institute of Geological Survey (EIGS) (2010). Geological Map of Ethiopia, 2nd ed., Unpublished technical report, EIGS, Addis Ababa, Ethiopia, 129 pp.
[5]	Gichile, S. (1992). Granulites in the Precambrian basement of southern Ethiopia: geochemistry, P–T conditions of metamorphism and tectonic setting. J Afr Earth Sci 15 pp. 251–263.
[6]	Kazmin, V., Shiferaw, A. and Balcha, T. (1978). The Ethiopian basement: stratigraphy and possible manner of evolution. Geologische Rundschau 67, pp. 531–546.
[7]	Kroner, A. and Stern, R. J. (2004). Pan-African orogeny, North African Phanerozoic, Rift valley, V 1, PP. 1-3.
[8]	Kusky, T. M., Abdelsalam, M., Stern, R. J. and Tucker, R. D. (eds.) (2003). Evolution of the East African and related orogens, and the assembly of Gondwana. Precambrian Res. 123, pp. 82-85.
[9]	McClay K R (1987). The Mapping of Geological Structures. Department of Geology Royal Holloway and Bedford New College University of London.
[10]	Samuel, G. (1991). Structure, metamorphism and tectonic setting of a gneissic terrane, the Sagan Afleta area, southern Ethiopia. Msc thesis, Ottawa-Carleton Geoscience center and University of Ottawa, Canada.
[11]	Santosh, M., Morimoto, T. and Tsutsumi, Y. (2006). Geochronology of the khondalite belt of Trivandrum Block, southern India: electron probe ages and implications for Gondwana tectonics. Gondwana Research 9, pp. 261–278.
[12]	Shackleton (1979, as cited in Asrat and Barbey, 2003) Petrology, geochronology and Sr-Nd isotopic geochemistry of the Konso pluton, south-western Ethiopia: implications for transition from convergence to extension in the Mozambique belt. Int journal of Earth Science (Geol Rundsch), 92, pp. 873-890.
[13]	Stern, R. J. (1994). Arc assembly and continental collision in the Neoproterozoic east African Orogen: implications for the consolidation of Gondwanaland. Annu. Rev. Earth Planet. Sci. Lett. 22, pp. 319–351.
[14]	Tadesse S., Milesi JP., Deschamps Y (2003). Geology and mineral potential of Ethiopia: a note on geology and mineral map of Ethiopia. Journal of African Earth Sciences. 36 (2003): 273–313.
[15]	Vaughan, A. P. M. and Pankhurst, R. J. (2008). Tectonic overview of the West Gondwana margin. Gondwana Research, 13, pp. 150–162.

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Muluken Fanta Bassa. (2020). Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia. International Journal of Environmental Monitoring and Analysis, 8(5), 130-143. https://doi.org/10.11648/j.ijema.20200805.12

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Muluken Fanta Bassa. Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia. Int. J. Environ. Monit. Anal. 2020, 8(5), 130-143. doi: 10.11648/j.ijema.20200805.12

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AMA Style

Muluken Fanta Bassa. Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia. Int J Environ Monit Anal. 2020;8(5):130-143. doi: 10.11648/j.ijema.20200805.12

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@article{10.11648/j.ijema.20200805.12,
  author = {Muluken Fanta Bassa},
  title = {Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia},
  journal = {International Journal of Environmental Monitoring and Analysis},
  volume = {8},
  number = {5},
  pages = {130-143},
  doi = {10.11648/j.ijema.20200805.12},
  url = {https://doi.org/10.11648/j.ijema.20200805.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijema.20200805.12},
  abstract = {The deformation history of Sorobo, Konso area (southern Ethiopia) within the Mozambique Belt, is described using microstructural and petrographic analysis. The area is characterized by folds and metamorphic fabrics that trend between NNE and NNW and consist of high-grade, amphibolite- to granulite-facies rocks. It is affected by five deformational phases (D1 to D5) and two metamorphic events (M1 & M2). During shortening deformation events (D1 to D3) the development of gneissosity (D1), the formation of tight to isoclinal and recumbent folds (D2) and the superposition of secondary (upright) fold (D3) on earlier recumbent fold resulting in type-3-fold interference pattern are formed respectively. During fourth deformation phase (D4) most of the rock units of the area are affected by shearing or shows east and west vergence. The area is affected by both sinistral and a dextral sense of shearing but dextral shear-sense appears dominant. Brittle type of deformation phase (D5) was developed and resulting in different types of faults varies in orientation. Peak progressive metamorphism of the granulite facies (M1) and retrogression (M2) are also associated with the deformational phase. An equal-area plot and rose diagram shows the orientation of all fabric, which indicates multiphase deformation. Geological structures in the study areas like faults, joints & fissures, shear zones and folds are important depositional sites for different hydrothermal economic mineral deposits.},
 year = {2020}
}

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TY  - JOUR
T1  - Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia
AU  - Muluken Fanta Bassa
Y1  - 2020/09/21
PY  - 2020
N1  - https://doi.org/10.11648/j.ijema.20200805.12
DO  - 10.11648/j.ijema.20200805.12
T2  - International Journal of Environmental Monitoring and Analysis
JF  - International Journal of Environmental Monitoring and Analysis
JO  - International Journal of Environmental Monitoring and Analysis
SP  - 130
EP  - 143
PB  - Science Publishing Group
SN  - 2328-7667
UR  - https://doi.org/10.11648/j.ijema.20200805.12
AB  - The deformation history of Sorobo, Konso area (southern Ethiopia) within the Mozambique Belt, is described using microstructural and petrographic analysis. The area is characterized by folds and metamorphic fabrics that trend between NNE and NNW and consist of high-grade, amphibolite- to granulite-facies rocks. It is affected by five deformational phases (D1 to D5) and two metamorphic events (M1 & M2). During shortening deformation events (D1 to D3) the development of gneissosity (D1), the formation of tight to isoclinal and recumbent folds (D2) and the superposition of secondary (upright) fold (D3) on earlier recumbent fold resulting in type-3-fold interference pattern are formed respectively. During fourth deformation phase (D4) most of the rock units of the area are affected by shearing or shows east and west vergence. The area is affected by both sinistral and a dextral sense of shearing but dextral shear-sense appears dominant. Brittle type of deformation phase (D5) was developed and resulting in different types of faults varies in orientation. Peak progressive metamorphism of the granulite facies (M1) and retrogression (M2) are also associated with the deformational phase. An equal-area plot and rose diagram shows the orientation of all fabric, which indicates multiphase deformation. Geological structures in the study areas like faults, joints & fissures, shear zones and folds are important depositional sites for different hydrothermal economic mineral deposits.
VL  - 8
IS  - 5
ER  -

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Author Information

Muluken Fanta Bassa

Department of Geology, Arbaminch University, Arbaminch, Ethiopia

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APA Style

Muluken Fanta Bassa. (2020). Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia. International Journal of Environmental Monitoring and Analysis, 8(5), 130-143. https://doi.org/10.11648/j.ijema.20200805.12

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ACS Style

Muluken Fanta Bassa. Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia. Int. J. Environ. Monit. Anal. 2020, 8(5), 130-143. doi: 10.11648/j.ijema.20200805.12

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AMA Style

Muluken Fanta Bassa. Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia. Int J Environ Monit Anal. 2020;8(5):130-143. doi: 10.11648/j.ijema.20200805.12

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@article{10.11648/j.ijema.20200805.12,
  author = {Muluken Fanta Bassa},
  title = {Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia},
  journal = {International Journal of Environmental Monitoring and Analysis},
  volume = {8},
  number = {5},
  pages = {130-143},
  doi = {10.11648/j.ijema.20200805.12},
  url = {https://doi.org/10.11648/j.ijema.20200805.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijema.20200805.12},
  abstract = {The deformation history of Sorobo, Konso area (southern Ethiopia) within the Mozambique Belt, is described using microstructural and petrographic analysis. The area is characterized by folds and metamorphic fabrics that trend between NNE and NNW and consist of high-grade, amphibolite- to granulite-facies rocks. It is affected by five deformational phases (D1 to D5) and two metamorphic events (M1 & M2). During shortening deformation events (D1 to D3) the development of gneissosity (D1), the formation of tight to isoclinal and recumbent folds (D2) and the superposition of secondary (upright) fold (D3) on earlier recumbent fold resulting in type-3-fold interference pattern are formed respectively. During fourth deformation phase (D4) most of the rock units of the area are affected by shearing or shows east and west vergence. The area is affected by both sinistral and a dextral sense of shearing but dextral shear-sense appears dominant. Brittle type of deformation phase (D5) was developed and resulting in different types of faults varies in orientation. Peak progressive metamorphism of the granulite facies (M1) and retrogression (M2) are also associated with the deformational phase. An equal-area plot and rose diagram shows the orientation of all fabric, which indicates multiphase deformation. Geological structures in the study areas like faults, joints & fissures, shear zones and folds are important depositional sites for different hydrothermal economic mineral deposits.},
 year = {2020}
}

Copy | Download

TY  - JOUR
T1  - Reconstructing Deformation History by Using Microstructural and Petrographic Analysis of Sorobo, Konso Area, Southern Ethiopia
AU  - Muluken Fanta Bassa
Y1  - 2020/09/21
PY  - 2020
N1  - https://doi.org/10.11648/j.ijema.20200805.12
DO  - 10.11648/j.ijema.20200805.12
T2  - International Journal of Environmental Monitoring and Analysis
JF  - International Journal of Environmental Monitoring and Analysis
JO  - International Journal of Environmental Monitoring and Analysis
SP  - 130
EP  - 143
PB  - Science Publishing Group
SN  - 2328-7667
UR  - https://doi.org/10.11648/j.ijema.20200805.12
AB  - The deformation history of Sorobo, Konso area (southern Ethiopia) within the Mozambique Belt, is described using microstructural and petrographic analysis. The area is characterized by folds and metamorphic fabrics that trend between NNE and NNW and consist of high-grade, amphibolite- to granulite-facies rocks. It is affected by five deformational phases (D1 to D5) and two metamorphic events (M1 & M2). During shortening deformation events (D1 to D3) the development of gneissosity (D1), the formation of tight to isoclinal and recumbent folds (D2) and the superposition of secondary (upright) fold (D3) on earlier recumbent fold resulting in type-3-fold interference pattern are formed respectively. During fourth deformation phase (D4) most of the rock units of the area are affected by shearing or shows east and west vergence. The area is affected by both sinistral and a dextral sense of shearing but dextral shear-sense appears dominant. Brittle type of deformation phase (D5) was developed and resulting in different types of faults varies in orientation. Peak progressive metamorphism of the granulite facies (M1) and retrogression (M2) are also associated with the deformational phase. An equal-area plot and rose diagram shows the orientation of all fabric, which indicates multiphase deformation. Geological structures in the study areas like faults, joints & fissures, shear zones and folds are important depositional sites for different hydrothermal economic mineral deposits.
VL  - 8
IS  - 5
ER  -

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