Rifting of the Kalahari Craton Through Botswana? New Seismic Evidence

Paulssen, Hanneke; Micallef, T.; Bouwman, D.R.; Ruigrok, Elmer; Herman, M. W.; Fadel, Islam; Meijde, M. van der; Kwadiba, M. T. O.; Maritinkole, Joseph; Ntibinyane, Onkgopotse

doi:10.1029/2021jb023524

Cited by 6 publications

(3 citation statements)

References 76 publications

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“…Indeed, most of the seismicity in the Makgadikgadi Basin is located in its southern part and cannot be correlated to the faults of the MRZ. Most events have a magnitude <4 and cluster around mining areas, whereas the 2017 Mw 6.5 earthquake, located more than 100 km further south, is correlated to the reactivation of NW‐SE Neoproterozoic faults related to the Zoetfontain Faults System (Kolawole et al., 2017; Mulabisana et al., 2021; Paulssen et al., 2022).…”

Section: Discussionmentioning

confidence: 99%

Geomorphology of the Makgadikgadi Basin (Botswana): Insight Into the Propagation of the East African Rift System

Gaudaré,

Dauteuil,

Jolivet

2024

Tectonics

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The Southwestern Branch of the East African Rift System propagates through the Central and Southern African plateaus and ends in the Okavango Makgadikgadi Zambezi Basin. This basin hosts the Okavango Graben and the Eiseb Graben, considered as the terminus of the Southwestern Branch of the rift. To the southeast, the Makgadikgadi Basin is affected by a series of normal faults forming the Makgadikgadi Rift Zone (MRZ) which regional geodynamic significance remains unclear. Based on fieldwork and geomorphic analysis, we revisited the geomorphological features associated with paleolakes and the fault pattern within the Makgadikgadi Basin to better constrain the dynamics of the MRZ. Fault scarps and offsets along linear dunes show normal‐dip kinematics of faults, indicating a NW‐SE extension direction in the area. Furthermore, lacustrine shorelines in the basin are undeformed, proving that they post‐date the fault activity. The previously published ages of these shorelines demonstrate that the MRZ currently has a low tectonic activity. Integrated in the geodynamic framework of the region, these results suggest that present‐day deformation shifts toward the Okavango Graben north of the MRZ. We therefore propose a “zip‐opening” model to explain the propagation of the Southwestern Branch of the East African Rift System where the tip of the system progressively progresses southwestward, driven by motions of the continental plates.

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Section: Discussionmentioning

confidence: 99%

Geomorphology of the Makgadikgadi Basin (Botswana): Insight Into the Propagation of the East African Rift System

Gaudaré,

Dauteuil,

Jolivet

2024

Tectonics

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“…According to Fadel et al (2020), the process that caused the earthquake suggests that it was associated with fluids or melt from the EARS. In a recent seismological study, Paulssen et al (2022) also support that the EARS further continues to central Botswana based on the upward migration of the relocated aftershocks and their extensional mechanism, suggesting the earthquakes were produced by fluid intrusion from the mantle causing the eclogitization of dry metastable granulite facies rocks. These divergent views on the extension of the EARS to Botswana require further exploration and understanding from other geophysical data and models.…”

Section: Introductionmentioning

confidence: 88%

“…Also, Moorkamp et al (2019) suggest that the 6.5 Mw earthquake reactivated existing fault from the deformation process of the collision between Kaapvaal and Zimbabwe cratonic blocks. However, other studies suggest that ascending fluids or melt from the EARS extends to central Botswana through the weak lithospheric zones and played a role in triggering the earthquake (Chisenga et al, 2020b;Fadel et al, 2020;Paulssen et al, 2022).…”

Section: The Extension Of the East African Rift System To Botswanamentioning

confidence: 99%

Crustal and Upper Mantle Imaging of Botswana Using Magnetotelluric Method

2022

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We used magnetotelluric data from 352 sites in Botswana to derive a country-wide electrical conductivity model of the crust and upper mantle structure. A robust methodological scheme and 3D inversion were used to derive a 3D electrical conductivity model with unprecedented spatial coverage. The model results show interesting features, including the major cratonic blocks and the mobile belts in Botswana. A distinctive resistive structure was imaged in southwest Botswana, which suggests the existence of the Maltahohe microcraton as a separate cratonic unit as proposed by other studies. Furthermore, the model gives new insight into the extension of the East African Rift System to Botswana and the incipient rifting in the Okavango Rift Zone. In northern Botswana, the electrical conductivity model shows a highly conductive structure beneath the Okavango Rift Zone, which connects with a deeper conductive structure that we attribute to the East African Rift System due to its vicinity to Lake Kariba, the last surface expression of the rift system. We suggest that ascending fluids or melt from the East African Rift System causes the weakening of the lithosphere and plays a significant role in the incipient continental rifting in the Okavango Rift Zone.

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Localization of large intraplate earthquakes along faulted density-contrast boundaries: Insights from the 2017 Mw6.5 Botswana earthquake

Chisenga

Kolawole

Rajaonarison

et al. 2023

Journal of African Earth Sciences

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Rifting of the Kalahari Craton Through Botswana? New Seismic Evidence

Abstract: Botswana is a country characterized by low to moderate seismic activity. It has long been thought that most earthquakes occur in the north along the Okavango Rift Zone, the southwestern terminus of the East African

Cited by 6 publications

References 76 publications

Geomorphology of the Makgadikgadi Basin (Botswana): Insight Into the Propagation of the East African Rift System

Geomorphology of the Makgadikgadi Basin (Botswana): Insight Into the Propagation of the East African Rift System

Crustal and Upper Mantle Imaging of Botswana Using Magnetotelluric Method

Localization of large intraplate earthquakes along faulted density-contrast boundaries: Insights from the 2017 Mw6.5 Botswana earthquake

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