Geometry and kinematics of the late Proterozoic Angavo Shear Zone, Central Madagascar: Implications for Gondwana Assembly

Tsilavo Raharimahefa; Timothy M. Kusky; Erkan Toraman; Christine Rasoazanamparany; Imboarina Rasaonina

doi:10.1016/j.tecto.2013.02.014

Geometry and kinematics of the late Proterozoic Angavo Shear Zone, Central Madagascar: Implications for Gondwana Assembly

Tsilavo Raharimahefa, Timothy M. Kusky, Erkan Toraman, Christine Rasoazanamparany, Imboarina Rasaonina

Earth and Environmental Sciences-Twin Cities

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

This paper documents the 20 to 60km wide N-S trending Angavo Shear Zone (ASZ) in central Madagascar and its tectonic implications by examining its structural styles, kinematics and geometry. Our study indicates that the ASZ is characterized by at least two ductile Late Proterozoic deformation events (D₁ and D₂) followed by a brittle neotectonic deformation (D₃). The early D₁ event produced a regionally extensive S₁ foliation, stretching/flattening mineral lineation L₁ and symmetrical structural fabrics such as recumbent and isoclinal intra-folial folds (F₁), implying a flattening deformation. D₁ deformational fabrics are locally overprinted by D₂ structures. D₂ is characterized by a penetrative S₂ foliation, shallow south plunging L₂ lineation, asymmetric and sheath folds (F₂) consistent with a right lateral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D₂ represents a non-coaxial flow regime formed in a dextral west over east shear zone during a partitioned transpression in response to east-west-directed compression during the assembly of Gondwana. A close resemblance with the Achankovil shear zone in India is noticed; however the continuation of the ASZ in Africa is uncertain.

Original language	English (US)
Pages (from-to)	113-129
Number of pages	17
Journal	Tectonophysics
Volume	592
DOIs	https://doi.org/10.1016/j.tecto.2013.02.014
State	Published - Apr 19 2013

Bibliographical note

Funding Information:
This work was supported by the NSF grant EAR-0221567 awarded to T. Kusky, and some of the field work was carried out under the auspices of the British Geological Survey and the U.S. Geological Survey , under the auspices of the World Bank Development of Madagascar Program and the Mineral Resource Assessment of Madagascar Project . The study was jointly funded by the National Natural Science Foundation of China (Grants 40821061 and 91014002 ) and the Ministry of Education of China ( B07039 ). We greatly appreciate Kathryn M. Goodenough for her constructive suggestions. We thank Alan S. Collins and an anonymous reviewer for comments that substantially improved the manuscript.

Keywords

Angavo Shear Zone
Gondwana
Madagascar
Tectonics

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10.1016/j.tecto.2013.02.014

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title = "Geometry and kinematics of the late Proterozoic Angavo Shear Zone, Central Madagascar: Implications for Gondwana Assembly",

abstract = "This paper documents the 20 to 60km wide N-S trending Angavo Shear Zone (ASZ) in central Madagascar and its tectonic implications by examining its structural styles, kinematics and geometry. Our study indicates that the ASZ is characterized by at least two ductile Late Proterozoic deformation events (D1 and D2) followed by a brittle neotectonic deformation (D3). The early D1 event produced a regionally extensive S1 foliation, stretching/flattening mineral lineation L1 and symmetrical structural fabrics such as recumbent and isoclinal intra-folial folds (F1), implying a flattening deformation. D1 deformational fabrics are locally overprinted by D2 structures. D2 is characterized by a penetrative S2 foliation, shallow south plunging L2 lineation, asymmetric and sheath folds (F2) consistent with a right lateral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D2 represents a non-coaxial flow regime formed in a dextral west over east shear zone during a partitioned transpression in response to east-west-directed compression during the assembly of Gondwana. A close resemblance with the Achankovil shear zone in India is noticed; however the continuation of the ASZ in Africa is uncertain.",

keywords = "Angavo Shear Zone, Gondwana, Madagascar, Tectonics",

author = "Tsilavo Raharimahefa and Kusky, {Timothy M.} and Erkan Toraman and Christine Rasoazanamparany and Imboarina Rasaonina",

note = "Funding Information: This work was supported by the NSF grant EAR-0221567 awarded to T. Kusky, and some of the field work was carried out under the auspices of the British Geological Survey and the U.S. Geological Survey , under the auspices of the World Bank Development of Madagascar Program and the Mineral Resource Assessment of Madagascar Project . The study was jointly funded by the National Natural Science Foundation of China (Grants 40821061 and 91014002 ) and the Ministry of Education of China ( B07039 ). We greatly appreciate Kathryn M. Goodenough for her constructive suggestions. We thank Alan S. Collins and an anonymous reviewer for comments that substantially improved the manuscript.",

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T2 - Implications for Gondwana Assembly

AU - Raharimahefa, Tsilavo

AU - Kusky, Timothy M.

AU - Toraman, Erkan

AU - Rasoazanamparany, Christine

AU - Rasaonina, Imboarina

N1 - Funding Information: This work was supported by the NSF grant EAR-0221567 awarded to T. Kusky, and some of the field work was carried out under the auspices of the British Geological Survey and the U.S. Geological Survey , under the auspices of the World Bank Development of Madagascar Program and the Mineral Resource Assessment of Madagascar Project . The study was jointly funded by the National Natural Science Foundation of China (Grants 40821061 and 91014002 ) and the Ministry of Education of China ( B07039 ). We greatly appreciate Kathryn M. Goodenough for her constructive suggestions. We thank Alan S. Collins and an anonymous reviewer for comments that substantially improved the manuscript.

PY - 2013/4/19

Y1 - 2013/4/19

N2 - This paper documents the 20 to 60km wide N-S trending Angavo Shear Zone (ASZ) in central Madagascar and its tectonic implications by examining its structural styles, kinematics and geometry. Our study indicates that the ASZ is characterized by at least two ductile Late Proterozoic deformation events (D1 and D2) followed by a brittle neotectonic deformation (D3). The early D1 event produced a regionally extensive S1 foliation, stretching/flattening mineral lineation L1 and symmetrical structural fabrics such as recumbent and isoclinal intra-folial folds (F1), implying a flattening deformation. D1 deformational fabrics are locally overprinted by D2 structures. D2 is characterized by a penetrative S2 foliation, shallow south plunging L2 lineation, asymmetric and sheath folds (F2) consistent with a right lateral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D2 represents a non-coaxial flow regime formed in a dextral west over east shear zone during a partitioned transpression in response to east-west-directed compression during the assembly of Gondwana. A close resemblance with the Achankovil shear zone in India is noticed; however the continuation of the ASZ in Africa is uncertain.

AB - This paper documents the 20 to 60km wide N-S trending Angavo Shear Zone (ASZ) in central Madagascar and its tectonic implications by examining its structural styles, kinematics and geometry. Our study indicates that the ASZ is characterized by at least two ductile Late Proterozoic deformation events (D1 and D2) followed by a brittle neotectonic deformation (D3). The early D1 event produced a regionally extensive S1 foliation, stretching/flattening mineral lineation L1 and symmetrical structural fabrics such as recumbent and isoclinal intra-folial folds (F1), implying a flattening deformation. D1 deformational fabrics are locally overprinted by D2 structures. D2 is characterized by a penetrative S2 foliation, shallow south plunging L2 lineation, asymmetric and sheath folds (F2) consistent with a right lateral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D2 represents a non-coaxial flow regime formed in a dextral west over east shear zone during a partitioned transpression in response to east-west-directed compression during the assembly of Gondwana. A close resemblance with the Achankovil shear zone in India is noticed; however the continuation of the ASZ in Africa is uncertain.

KW - Angavo Shear Zone

KW - Gondwana

KW - Madagascar

KW - Tectonics

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DO - 10.1016/j.tecto.2013.02.014

M3 - Article

AN - SCOPUS:84875814698

SN - 0040-1951

VL - 592

SP - 113

EP - 129

JO - Tectonophysics

JF - Tectonophysics

ER -

Geometry and kinematics of the late Proterozoic Angavo Shear Zone, Central Madagascar: Implications for Gondwana Assembly

Abstract

Bibliographical note

Keywords

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