Lithostratigraphy of the Kalahari Group in northeastern Namibia

Wanke, Heike; Wanke, A.

doi:10.1016/j.jafrearsci.2007.05.002

Cited by 12 publications

(4 citation statements)

References 25 publications

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“…This large igneous province is attributed to magmatic processes associated with West Gondwana passing over the Tristan da Cuhna hotspot (Hoernle et al., 2015; O’Connor et al., 2012), contemporaneous with the northward‐propagating breakup of South America from Africa. The onshore post‐rift geology is limited to minor alkaline intrusions and thin (0–400 m) terrestrial Cenozoic deposits of the Kalahari Group that thicken toward the northeast (Marsh, 2010; Wanke & Wanke, 2007; Ward, 1988; Ward & Martin, 1987).…”

Section: Geological Settingmentioning

confidence: 99%

From sink to source: Using offshore thermochronometric data to extract onshore erosion signals in Namibia

et al. 2021

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Products of onshore passive continental margin erosion are best preserved in offshore sedimentary basins. Therefore, these basins potentially hold a recoverable record of the onshore erosion history. Here, we present apatite fission track (AFT) data for 13 samples from a borehole in the southern Walvis basin, offshore Namibia. All samples show AFT central ages older or similar to their respective stratigraphic ages, while many single grain ages are older, implying none of the samples has been totally annealed post-deposition. Furthermore, large dispersion in single grain ages in some samples suggests multiple age components related to separate source regions. Using Bayesian mixture modelling we classify single grain ages from a given sample to particular age components to create 'subsamples' and then jointly invert the entire dataset to obtain a thermal history. For each sample, the post-depositional thermal history is required to be the same for all age components, but each component ('subsample') has an independent pre-depositional thermal history. With this approach we can resolve pre-and post-depositional thermal events and identify changes in sediment provenance in response to the syn-and post-rift tectonic evolution of Namibia and southern Africa. Apatite U-Pb and compositional data obtained during the acquisition of LA-ICP-MS FT data are also presented to help track changes in provenance with time. We constrain multiple thermal events linked to the exhumation and burial history of the continental and offshore sectors of the margin over a longer timescale than has been possible using only onshore AFT thermochronological data.

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Section: Geological Settingmentioning

confidence: 99%

From sink to source: Using offshore thermochronometric data to extract onshore erosion signals in Namibia

et al. 2021

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“…Basins formed in rift-related flexural troughs are uncommon, or at least not widely recognized (e.g., van Balen et al, 1995). Examples include the Kalahari basin associated with the Great Escarpment in southern Africa, the Wilkes basin associated with the west Antarctic rift system, the Manesi, Trichonis, Copais, and Istiea basins associated with the Corinth rift in Greece, and the Estancia basin in the Rio Grande rift (Poulimenos & Doutsos, 1997;Roy et al, 1999;ten Brink & Stern, 1992;van Wijk, Lawrence, & Driscoll, 2008;van Wijk, Van Hunen, & Goes, 2008;Wanke & Wanke, 2007). The relative scarcity of rift-flank flexural trough basins reported in the literature is somewhat surprising considering the likelihood for preservation, particularly in comparison to back-bulge depozones, another type of flexural basin.…”

Section: Deposition In a Flexural Troughmentioning

confidence: 99%

Beveling the Colorado Plateau: Early Mesozoic Rift‐Related Flexure Explains Erosion and Anomalous Deposition in the Southern Cordilleran Foreland Basin

Chapman

DeCelles

2021

Tectonics

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“…Initial deposition of the Kalahari group sediments is widely accepted to have been initiated in the Late Cretaceous by tectonism resulting in basin development along a NW-SE axis. Subsequent tectonism along a NE-SW axis, continuing up to the present time, has modified the location and the ages of the principal deposition episodes of Kalahari group sediments (Wanke and Wanke 2007). Kalahari group sediments generally include widespread basal gravel and a fining upwards sequence with sedimentary facies ranging from coarse clastic proximal facies to distal fine grained mudstones and evaporites (e.g.…”

Section: Geologymentioning

confidence: 99%

“…Du Plessis and Le Roux 1995). The dominant depositional environment was fluvial, especially for lower units (Wanke and Wanke 2007), while the widespread upper unconsolidated sand is generally accepted to have an aeolian origin (e.g. Thomas 1987).…”

Section: Geologymentioning

confidence: 99%

Inherited drainage - paleochannels and preferential groundwater flow

Owen

Dahlin

2010

Hydrogeol J

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It is suggested that in a localized remnant of Kalahari sand at Dufuya, central Zimbabwe, groundwater flows in an integrated pattern inherited from the paleochannel network of the underlying gneiss. Contact springs occur at discrete localities along the Kalahari sand/gneiss boundary and are associated with spring sapping and land surface subsidence. Subsidence is presumed to be due to preferential solute removal by leaching and dissolution as a result of concentration of groundwater flow within the buried paleochannel network and the location of the springs is presumed to occur where the paleochannel network intersects the Kalahari sand/gneiss boundary. Over time the surficial Kalahari sand is preferentially removed along these buried drainage lines by spring sapping and headwards erosion, exposing the gneiss. Multi-electrode direct current resistivity profiling and radar have been used to map the subsurface, revealing the topography of the basement and nature of the Kalahari cover. Coincidence of gneiss basement depressions with the spring sites, leached sands and subsidence zones suggests inheritance of the gneiss fluvial paleochannel network pattern by the present day groundwater flow. Washed sand and gravel intersected in shallow boreholes in these areas provides further evidentiary support for the concept of inherited drainage.

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Lithostratigraphy of the Kalahari Group in northeastern Namibia

Cited by 12 publications

References 25 publications

From sink to source: Using offshore thermochronometric data to extract onshore erosion signals in Namibia

From sink to source: Using offshore thermochronometric data to extract onshore erosion signals in Namibia

Beveling the Colorado Plateau: Early Mesozoic Rift‐Related Flexure Explains Erosion and Anomalous Deposition in the Southern Cordilleran Foreland Basin

Inherited drainage - paleochannels and preferential groundwater flow

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