Scientific Drilling in the East African Rift Lakes: A Strategic Planning Workshop

Russell, James M.; Cohen, Andrew S.; Johnson, T. C.; Scholz, Christopher A.

doi:10.5194/sd-14-49-2012

Cited by 7 publications

(8 citation statements)

References 9 publications

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“…This ridge is argued to be a long-lived structural-high in the Tanganyika Basin, which served as a paleo-drainage divide during periods of lowstands (Scholz and Rosendahl, 1988). Such large structurally controlled paleo-drainage divides commonly modulate biodiversity patterns in active continental rift environments (e.g., Russell et al, 2012;Dommain et al, 2022), demonstrating the roles of RIZ evolution on sedimentary depositional environment, landscape evolution, and floral and faunal speciation gradients.…”

Section: Controls Of Rift Interaction Zone Geometry On Early Vs Delay...mentioning

confidence: 99%

Rapid Versus Delayed Linkage and Coalescence of Propagating Rift Tips

Kolawole¹,

Xue²,

Dulanya³

2023

Preprint

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The tectonic interaction, linkage, and coalescence of propagating isolated rift segments create a through-going along-axis rift floor without which a continental break-up axis cannot develop.However, prior to linkage, interacting rift segments are separated by a topographic basement-high (rift interaction zone, RIZ) which is progressively dismembered and down-thrown by the lateral propagation of rift tip faulting and their hanging wall subsidence. Here, we explore the evolution of the Middle-Shire and Nsanje RIZs located along three slowly extending (~2.2 mm/yr) contiguous propagating rift segments: the southern Malawi Rift, Lower-Shire Graben, and the Nsanje Graben, East Africa. The Middle-Shire RIZ is an overlapping-oblique RIZ in which the NNE/N-trending Malawi Rift is propagating into the shoulder of the NW-trending Lower-Shire Graben, whereas the Nsanje RIZ is a tip-to-tip oblique RIZ in which the Lower-Shire Graben has propagated into the tip of the N-trending Nsanje Graben. These rift zones provide non-volcanic natural examples to explore tectonic strain localization on rift tips and syn-rift RIZ surface processes. We use a landscape evolution model with implemented fault displacement fields of two contiguous RIZs with contrasting geometries, to simulate their geomorphic evolution, and apply a static stress model to evaluate the stress transfer patterns during RIZ evolution. The model results successfully reproduce natural observations in the study area, in which, with progressive extension and tip growth, the Middle-Shire RIZ maintains minor basement down-throw and an unequilibrated axial stream profile, which contrasts the widespread basement burial and equilibrated axial stream profile across the Nsanje RIZ.Modeled static stress distribution predict compounding stress concentrations at tip-to-tip RIZs, favoring brittle strain localization and rift coalescence, and stress relaxation at overlapping oblique RIZs, favoring stalled rift coalescence. We argue that RIZ geometry strongly influences the pace of rift coalescence by modulating the spatial distribution of tectonic stresses necessary to promote riftlinking deformation and the associated surface processes.

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Section: Controls Of Rift Interaction Zone Geometry On Early Vs Delay...mentioning

confidence: 99%

Rapid Versus Delayed Linkage and Coalescence of Propagating Rift Tips

Kolawole¹,

Xue²,

Dulanya³

2023

Preprint

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“…With Lake Tanganyika, the next-and somewhat ultimatetarget for scientific drilling in East Africa has already been identified (19). A well-resolved paleoecological record for Tanganyika, which harbors the eco-morphologically most diverse cichlid assemblages (albeit counting fewer species than the one in Malawi) (2), would allow scrutinization of the relative contribution of environmental factors on organismal diversification.…”

Section: Environmental Triggers For Cichlid Adaptive Radiationmentioning

confidence: 99%

Environmental context for understanding the iconic adaptive radiation of cichlid fishes in Lake Malawi

Malinsky

Salzburger

2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Further studies of sediments within rift basins across the region, such as Lake Albert, Lake Rukwa and Lake Tanganyika, are necessary to effectively determine the timing of extensional onset. Although attempts are being made to investigate deeper sequences in rift lakes (Russell et al, 2012), stratigraphic evidence to support early initiation of rifting remains elusive. The results of this work alongside previous studies suggest the topography of the Western Brach of the East African Rift likely dates back to the Eocene and thus, the modern consensus on rift initiation requires review.…”

Section: Implications For the History Of The East African Riftmentioning

confidence: 99%

Paleogene initiation of the Western Branch of the East African Rift: The uplift history of the Rwenzori Mountains, Western Uganda

Jess

Koehn

Fox

et al. 2020

Earth and Planetary Science Letters

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The two branches of the East African Rift System (EARS) are believed to have initiated diachronously. However, a growing body of work continues to suggest the onset of rifting in the Western Branch occurred in the Palaeogene, coeval to the Eastern Branch. Due to a lack of pre-Miocene stratigraphy, attempts to resolve the geological history of the Western Branch must study the uplift and erosional histories of the modern rift topography. In this study, the rock uplift history of the Rwenzori Mountains, Western Uganda, is resolved to better our understanding of the tectonic history of the Western Branch of the EAR. Through the application of low-temperature thermochronology, -mapping and the modelling of river profiles, we show that rock uplift of the Rwenzori dates back to the Oligocene, with thermal history models suggesting uplift induced exhumation may date back as far as the Eocene. This provides tangible evidence that extension began in the region in the Paleogene, coeval with the Eastern Branch, and not the late Neogene. These results have broad implications for the tectonic evolution of the entire East African Rift System and suggest our current understanding of the region's rift history remains incomplete.

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Scientific Drilling in the East African Rift Lakes: A Strategic Planning Workshop

Abstract: No abstract available. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.14.08.2012" target="_blank">10.2204/iodp.sd.14.08.2012</a>

Cited by 7 publications

References 9 publications

Rapid Versus Delayed Linkage and Coalescence of Propagating Rift Tips

Rapid Versus Delayed Linkage and Coalescence of Propagating Rift Tips

Environmental context for understanding the iconic adaptive radiation of cichlid fishes in Lake Malawi

Paleogene initiation of the Western Branch of the East African Rift: The uplift history of the Rwenzori Mountains, Western Uganda

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