Structural framework of the Lufilian Fold Belt in the Domes region of North Western Province, Zambia from interpretation of geophysical data

P. R. Williams, B. W. Nisbet

Research output: Contribution to journalArticle

Abstract

The area around the Kabompo and Mwombezhi Domes in the North Western Province of Zambia is characterized by poor outcrop, and as is common with other areas in Zambia, correlation of units between isolated outcrops is complicated by the similarity of lithology in many sections of the stratigraphy. Aeromagnetic data, airborne radiometric and electromagnetic data were used to provide control on correlation between outcrops, and therefore allowed interpretation of a robust structural framework. The two domes are Paleoproterozoic basement-cored anticlines unconformably overlain by Neoproterozoic Roan Group rocks of the lower Katangan Supergroup. The Katangan Supergroup was deposited in an extensional basin formed as part of the breakup of the supercontinent Rodinia. From the geophysical interpretation several normal faults are identified that probably formed during this stage of basin formation, and there is good evidence for at least four regional transfer zones having formed at this time. The fault architecture initiated during the Katangan extensional tectonic event is shown in this interpretation to have strongly influenced the geometry of the Lufilian Fold Belt. Evidence in the domes area suggests that salt tectonics may explain the localization of the regional décollement at the top of the Lower Roan, and provide a structural mechanism for the formation of high-pressure metamorphic rocks in the area. Sinistral reverse faulting and associated folding dominates the Lufilian structural fabric in the east of area, and these faults appear to sole out on the regional décollement. Sigmoidal fold profiles have developed between adjacent fault zones, with east-west oriented fold axes in more distal areas rotating into parallelism adjacent to the faults, suggesting synchronous folding and faulting during north-directed compression. In the north-western part of the study area, fold hinge orientations and basement-cover interactions, indicate north north-westerly directed compression. The study demonstrates that interpretation of combined geological and geophysical mapping at a scale suitable for resolving unit correlations, the deformation sequence and local compression directions, is effective at resolving the extensional and compressional structures that now control the Lufilian Fold Belt structural framework.

LanguageEnglish
Pages542-557
Number of pages16
JournalJournal of African Earth Sciences
Volume129
DOIs
StatePublished - 1 May 2017

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fold belt
dome
outcrop
decollement
compression
fold
folding
faulting
salt tectonics
transfer zone
Rodinia
aeromagnetic survey
supercontinent
extensional tectonics
basin evolution
anticline
westerly
metamorphic rock
normal fault
fault zone

Cite this

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title = "Structural framework of the Lufilian Fold Belt in the Domes region of North Western Province, Zambia from interpretation of geophysical data",
abstract = "The area around the Kabompo and Mwombezhi Domes in the North Western Province of Zambia is characterized by poor outcrop, and as is common with other areas in Zambia, correlation of units between isolated outcrops is complicated by the similarity of lithology in many sections of the stratigraphy. Aeromagnetic data, airborne radiometric and electromagnetic data were used to provide control on correlation between outcrops, and therefore allowed interpretation of a robust structural framework. The two domes are Paleoproterozoic basement-cored anticlines unconformably overlain by Neoproterozoic Roan Group rocks of the lower Katangan Supergroup. The Katangan Supergroup was deposited in an extensional basin formed as part of the breakup of the supercontinent Rodinia. From the geophysical interpretation several normal faults are identified that probably formed during this stage of basin formation, and there is good evidence for at least four regional transfer zones having formed at this time. The fault architecture initiated during the Katangan extensional tectonic event is shown in this interpretation to have strongly influenced the geometry of the Lufilian Fold Belt. Evidence in the domes area suggests that salt tectonics may explain the localization of the regional d{\'e}collement at the top of the Lower Roan, and provide a structural mechanism for the formation of high-pressure metamorphic rocks in the area. Sinistral reverse faulting and associated folding dominates the Lufilian structural fabric in the east of area, and these faults appear to sole out on the regional d{\'e}collement. Sigmoidal fold profiles have developed between adjacent fault zones, with east-west oriented fold axes in more distal areas rotating into parallelism adjacent to the faults, suggesting synchronous folding and faulting during north-directed compression. In the north-western part of the study area, fold hinge orientations and basement-cover interactions, indicate north north-westerly directed compression. The study demonstrates that interpretation of combined geological and geophysical mapping at a scale suitable for resolving unit correlations, the deformation sequence and local compression directions, is effective at resolving the extensional and compressional structures that now control the Lufilian Fold Belt structural framework.",
keywords = "Basin inversion, D{\'e}collement, Extensional structures, Geophysical interpretation, Lufilian fold belt Zambia, Structural framework",
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T1 - Structural framework of the Lufilian Fold Belt in the Domes region of North Western Province, Zambia from interpretation of geophysical data

AU - Williams,P. R.

AU - Nisbet,B. W.

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N2 - The area around the Kabompo and Mwombezhi Domes in the North Western Province of Zambia is characterized by poor outcrop, and as is common with other areas in Zambia, correlation of units between isolated outcrops is complicated by the similarity of lithology in many sections of the stratigraphy. Aeromagnetic data, airborne radiometric and electromagnetic data were used to provide control on correlation between outcrops, and therefore allowed interpretation of a robust structural framework. The two domes are Paleoproterozoic basement-cored anticlines unconformably overlain by Neoproterozoic Roan Group rocks of the lower Katangan Supergroup. The Katangan Supergroup was deposited in an extensional basin formed as part of the breakup of the supercontinent Rodinia. From the geophysical interpretation several normal faults are identified that probably formed during this stage of basin formation, and there is good evidence for at least four regional transfer zones having formed at this time. The fault architecture initiated during the Katangan extensional tectonic event is shown in this interpretation to have strongly influenced the geometry of the Lufilian Fold Belt. Evidence in the domes area suggests that salt tectonics may explain the localization of the regional décollement at the top of the Lower Roan, and provide a structural mechanism for the formation of high-pressure metamorphic rocks in the area. Sinistral reverse faulting and associated folding dominates the Lufilian structural fabric in the east of area, and these faults appear to sole out on the regional décollement. Sigmoidal fold profiles have developed between adjacent fault zones, with east-west oriented fold axes in more distal areas rotating into parallelism adjacent to the faults, suggesting synchronous folding and faulting during north-directed compression. In the north-western part of the study area, fold hinge orientations and basement-cover interactions, indicate north north-westerly directed compression. The study demonstrates that interpretation of combined geological and geophysical mapping at a scale suitable for resolving unit correlations, the deformation sequence and local compression directions, is effective at resolving the extensional and compressional structures that now control the Lufilian Fold Belt structural framework.

AB - The area around the Kabompo and Mwombezhi Domes in the North Western Province of Zambia is characterized by poor outcrop, and as is common with other areas in Zambia, correlation of units between isolated outcrops is complicated by the similarity of lithology in many sections of the stratigraphy. Aeromagnetic data, airborne radiometric and electromagnetic data were used to provide control on correlation between outcrops, and therefore allowed interpretation of a robust structural framework. The two domes are Paleoproterozoic basement-cored anticlines unconformably overlain by Neoproterozoic Roan Group rocks of the lower Katangan Supergroup. The Katangan Supergroup was deposited in an extensional basin formed as part of the breakup of the supercontinent Rodinia. From the geophysical interpretation several normal faults are identified that probably formed during this stage of basin formation, and there is good evidence for at least four regional transfer zones having formed at this time. The fault architecture initiated during the Katangan extensional tectonic event is shown in this interpretation to have strongly influenced the geometry of the Lufilian Fold Belt. Evidence in the domes area suggests that salt tectonics may explain the localization of the regional décollement at the top of the Lower Roan, and provide a structural mechanism for the formation of high-pressure metamorphic rocks in the area. Sinistral reverse faulting and associated folding dominates the Lufilian structural fabric in the east of area, and these faults appear to sole out on the regional décollement. Sigmoidal fold profiles have developed between adjacent fault zones, with east-west oriented fold axes in more distal areas rotating into parallelism adjacent to the faults, suggesting synchronous folding and faulting during north-directed compression. In the north-western part of the study area, fold hinge orientations and basement-cover interactions, indicate north north-westerly directed compression. The study demonstrates that interpretation of combined geological and geophysical mapping at a scale suitable for resolving unit correlations, the deformation sequence and local compression directions, is effective at resolving the extensional and compressional structures that now control the Lufilian Fold Belt structural framework.

KW - Basin inversion

KW - Décollement

KW - Extensional structures

KW - Geophysical interpretation

KW - Lufilian fold belt Zambia

KW - Structural framework

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DO - 10.1016/j.jafrearsci.2017.01.029

M3 - Article

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SP - 542

EP - 557

JO - Journal of African earth sciences

T2 - Journal of African earth sciences

JF - Journal of African earth sciences

SN - 1464-343X

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