Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa
Abstract The Central African Plateau (CAP) covers a million square kilometers of African lithosphere absent of recent volcanism and intense seismicity. Treating the CAP erosion surface as a reference frame for measuring continental deformation reveals an active landscape of normal fault systems and...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2020-06-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1029/2019GC008746 |
| _version_ | 1797638109059350528 |
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| author | M. C. Daly P. Green A. B. Watts O. Davies F. Chibesakunda R. Walker |
| author_facet | M. C. Daly P. Green A. B. Watts O. Davies F. Chibesakunda R. Walker |
| author_sort | M. C. Daly |
| collection | DOAJ |
| description | Abstract The Central African Plateau (CAP) covers a million square kilometers of African lithosphere absent of recent volcanism and intense seismicity. Treating the CAP erosion surface as a reference frame for measuring continental deformation reveals an active landscape of normal fault systems and crustal flexures. Free‐air gravity anomalies over the CAP reveal both a short‐wavelength (100–200 km) flexural and a longer‐wavelength (>500 km) mantle convective signature. Apatite fission track thermochronometry records the onset of regional cooling of the erosion surface below 60 °C between 38 and 22 Ma. The erosion surface was formed by the Latest Miocene and elevated to its present altitude (1,200 ± 50 m) in the Latest Miocene/Pliocene. High‐resolution Shuttle Radar Topography Mission‐ and LIDAR‐based digital elevation models of the erosion surface show active fault terraces and alluvial fan deformation associated with pre‐existing rift border faults. Flexural modeling of the footwall uplift of the Luangwa Rift border fault yields an effective elastic thickness of the CAP lithosphere of ~35 km. The rifting initiated in the Pliocene with, or soon after, elevation of the CAP. Subsequent Plio‐Pleistocene deformation of the CAP surface controls the Congo and Zambezi drainage systems and wetland locations. The CAP rifts link southwestward through the Zambezi, Kafue and Muchili Rifts to the Pleistocene aged Okavango and Eiseb Rifts of Botswana and Namibia, defining a propagating Southwestern Rift cutting the Nubian Plate. This active rift system developed along relatively thin (~150 km) lithosphere between the Congo and Kalahari cratons within crust inherited from Neoproterozoic collisional tectonics. |
| first_indexed | 2024-03-11T12:57:53Z |
| format | Article |
| id | doaj.art-c69b7147fc0d46d8a61a2f67f1559cce |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:57:53Z |
| publishDate | 2020-06-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-c69b7147fc0d46d8a61a2f67f1559cce2023-11-03T16:56:04ZengWileyGeochemistry, Geophysics, Geosystems1525-20272020-06-01216n/an/a10.1029/2019GC008746Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in AfricaM. C. Daly0P. Green1A. B. Watts2O. Davies3F. Chibesakunda4R. Walker5Department of Earth Sciences University of Oxford Oxford UKGeotrack International Brunswick West Victoria AustraliaDepartment of Earth Sciences University of Oxford Oxford UKDepartment of Earth Sciences University of Oxford Oxford UKDepartment of Geological Survey Geological Survey of Zambia Lusaka ZambiaDepartment of Earth Sciences University of Oxford Oxford UKAbstract The Central African Plateau (CAP) covers a million square kilometers of African lithosphere absent of recent volcanism and intense seismicity. Treating the CAP erosion surface as a reference frame for measuring continental deformation reveals an active landscape of normal fault systems and crustal flexures. Free‐air gravity anomalies over the CAP reveal both a short‐wavelength (100–200 km) flexural and a longer‐wavelength (>500 km) mantle convective signature. Apatite fission track thermochronometry records the onset of regional cooling of the erosion surface below 60 °C between 38 and 22 Ma. The erosion surface was formed by the Latest Miocene and elevated to its present altitude (1,200 ± 50 m) in the Latest Miocene/Pliocene. High‐resolution Shuttle Radar Topography Mission‐ and LIDAR‐based digital elevation models of the erosion surface show active fault terraces and alluvial fan deformation associated with pre‐existing rift border faults. Flexural modeling of the footwall uplift of the Luangwa Rift border fault yields an effective elastic thickness of the CAP lithosphere of ~35 km. The rifting initiated in the Pliocene with, or soon after, elevation of the CAP. Subsequent Plio‐Pleistocene deformation of the CAP surface controls the Congo and Zambezi drainage systems and wetland locations. The CAP rifts link southwestward through the Zambezi, Kafue and Muchili Rifts to the Pleistocene aged Okavango and Eiseb Rifts of Botswana and Namibia, defining a propagating Southwestern Rift cutting the Nubian Plate. This active rift system developed along relatively thin (~150 km) lithosphere between the Congo and Kalahari cratons within crust inherited from Neoproterozoic collisional tectonics.https://doi.org/10.1029/2019GC008746Oligo‐Miocene erosion surfaceCentral African Plateau formationrifting and flexure of the plateauPlio‐Quaternary Southwestern Riftbreaking of the Nubian Plateconvective and flexural processes |
| spellingShingle | M. C. Daly P. Green A. B. Watts O. Davies F. Chibesakunda R. Walker Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa Geochemistry, Geophysics, Geosystems Oligo‐Miocene erosion surface Central African Plateau formation rifting and flexure of the plateau Plio‐Quaternary Southwestern Rift breaking of the Nubian Plate convective and flexural processes |
| title | Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa |
| title_full | Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa |
| title_fullStr | Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa |
| title_full_unstemmed | Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa |
| title_short | Tectonics and Landscape of the Central African Plateau and their Implications for a Propagating Southwestern Rift in Africa |
| title_sort | tectonics and landscape of the central african plateau and their implications for a propagating southwestern rift in africa |
| topic | Oligo‐Miocene erosion surface Central African Plateau formation rifting and flexure of the plateau Plio‐Quaternary Southwestern Rift breaking of the Nubian Plate convective and flexural processes |
| url | https://doi.org/10.1029/2019GC008746 |
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