The stratigraphic evolution of the Lake Tanganyika Rift, East Africa: Facies distributions and paleo-environmental implications

Shaban, Shaidu; Scholz, Christopher A.; Muirhead, James D.; Wood, Douglas A.

doi:10.1016/j.palaeo.2021.110474

Cited by 8 publications

(24 citation statements)

References 81 publications

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“…The expression of Lake Taupō south of the Oruanui structural caldera resembles a typical linear rift lake (e.g., Lake Tanganyika; Wright et al, 2020;Shaban et al, 2021). Subsidence in southern Lake Taupō occurs largely on the downthrown side of the Waihi fault, with the footwall of this structure forming the NE-trending Karangahape Cliffs on the western edge of the lake (Wilson, 2001) (Figure 2).…”

Section: Frontiers Inmentioning

confidence: 99%

Stretching, Shaking, Inflating: Volcanic-Tectonic Interactions at a Rifting Silicic Caldera

et al. 2022

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Silicic caldera volcanoes are frequently situated in regions of tectonic extension, such as continental rifts, and are subject to periods of unrest and/or eruption that can be triggered by the interplay between magmatic and tectonic processes. Modern (instrumental) observations of deformation patterns associated with magmatic and tectonic unrest in the lead up to eruptive events at silicic calderas are sparse. Therefore, our understanding of the magmatic-tectonic processes associated with volcanic unrest at silicic calderas is largely dependent on historical and geological observations. Here we utilize existing instrumental, historical and geological data to provide an overview of the magmatic-tectonic deformation patterns operating over annual to 104 year timescales at Taupō volcano, now largely submerged beneath Lake Taupō, in the rifted-arc of the Taupō Volcanic Zone. Short-term deformation patterns observed from seismicity, lake level recordings and historical records are characterized by decadal-scale uplift and subsidence with accompanying seismic swarms, ground shaking and surface ruptures, many of which may reflect magma injections into and around the magma reservoir. The decadal-scale frequency at which intense seismic events occur shows that ground shaking, rather than volcanic eruptions, is the primary short-term local hazard in the Taupō District. Deformation trends near and in the caldera on 101–104 yr timescales are atypical of the longer-term behavior of a continental rift, with magma influx within the crust suppressing axial subsidence of the rift basin within ∼10 km of the caldera margin. Examination of exposed faults and fissures reveals that silicic volcanic eruptions from Taupō volcano are characterized by intense syn-eruptive deformation that can occasionally extend up to 50 km outside the caldera structure, including ground shaking, fissuring and triggered fault movements. We conclude that eruption and unrest scenarios at Taupō volcano depend on the three-way coupling between the mafic-silicic-tectonic systems, with eruption and/or unrest events leading to six possible outcomes initially triggered by mafic injection either into or outside the magma mush system, or by changes to the tectonic stress state.

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Section: Frontiers Inmentioning

confidence: 99%

Stretching, Shaking, Inflating: Volcanic-Tectonic Interactions at a Rifting Silicic Caldera

et al. 2022

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“…According to Jacobsen (1987), if a potential field is upward continued to a height z , then sources situated at a depth greater than 0.5 z can be imaged. Based on the 2D seismic data the crystalline basement in the LTR is perceived within 5–6 km (Muirhead et al., 2019; Rosendahl, 1987; Shaban et al., 2021; Wright et al., 2020); therefore, to remove the short wavelength anomalies corresponding to intra‐sedimentary depth intervals, the data was upward‐continued at 12 km. Furthermore, we used other derivatives such as adaptive tilt angle (ATA) and tilt derivative horizontal derivative (TDX) from the FTG anomaly ( T z ) data to delineate lineaments (refer to the Supporting Information S1).…”

Section: Methodsmentioning

confidence: 99%

“…It is endowed with one of the oldest and most continuous records of tropical climate on the continents (Russell et al, 2020). The LTR is composed of a series of half grabens, typically ∼80-140 km long and ∼50-70 km wide (Muirhead et al, 2019;Rosendahl, 1987;Rosendahl et al, 1986;Shaban et al, 2021;Wright et al, 2020). Shaban et al (2021) suggested three main bathymetric basins (Ruzizi, Kigoma, and Marungu-Mpulungu basins) and several sub-basins from the northern end to the southern end of the LTR (Figure 1b).…”

Section: Lake Tanganyika Rift (Ltr)mentioning

confidence: 99%

“…It is endowed with one of the oldest and most continuous records of tropical climate on the continents (Russell et al., 2020). The LTR is composed of a series of half grabens, typically ∼80–140 km long and ∼50–70 km wide (Muirhead et al., 2019; Rosendahl, 1987; Rosendahl et al., 1986; Shaban et al., 2021; Wright et al., 2020). Shaban et al.…”

Section: Introductionmentioning

confidence: 99%

“…S2–S6 generally record deeper water rift lake sequences, manifested by the increasing dominance of the high amplitude and parallel to semi‐parallel seismic reflections. S3–S5 records facies variability with higher proportion of chaotic seismic reflections and influence of alternating high‐ and low lake levels (Figure 2c), indicating system with increasing relief (Shaban et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

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The Deep Basin and Underlying Basement Structure of the Tanganyika Rift

2023

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The oldest structures in a rift basin define incipient rift architecture, and commonly modulate the patterns of landscape evolution, sedimentation, and associated hazards in subsequent phases of rift development. However, due to deep burial beneath younger, thick syn‐rift sequences, and limited resolution of seismic imaging, critical early‐rift processes remain poorly understood. In the Tanganyika Rift, East Africa, we augment existing 2‐dimensional (2‐D) seismic reflection data with newly acquired aeromagnetic and Full‐Tensor Gradiometry data to assess the deep basin and underlying basement structure. Aeromagnetic and gravity grids show a dominance of NW‐trending long‐wavelength (>5 km) structural fabrics corresponding to the deeper basement, and dominant NW‐trending with a secondary NNE‐trending shorter‐wavelength (<3 km) fabric representing shallower, intra‐basin structures. Seismically‐constrained 2‐D forward modeling of the aeromagnetic and gravity data reveals: (a) an anomalously high‐density (2.35–2.45 g/cc) deep‐seated, fault‐bounded wedge‐shaped sedimentary unit that directly overlies the pre‐rift basement, likely of Mesozoic (Karoo) origin; (b) ∼4 km‐wide sub‐vertical low‐density (2.71 g/cc) structures within the 3.2 g/cc basement, interpreted to be inherited basement shear zones, (c) early‐rift intra‐basin faults co‐located with the modeled shear zone margins, in some places defining a persistent structurally‐controlled intra‐basin “high,” and (d) a shallow intra‐sedimentary V‐shaped zone of comparatively dense material (∼2.2 g/cc), interpreted to be a younger axial channel complex confined between the intra‐basin “high” and border fault. These results provide new insight into the earliest basin architecture of the Tanganyika Rift, controlled by inherited basement structure, and provide evidence of their persistent influence on the subsequent basin evolution.

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Macheyeki,

Kafumu

2024

The East African Rift System

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The stratigraphic evolution of the Lake Tanganyika Rift, East Africa: Facies distributions and paleo-environmental implications

Cited by 8 publications

References 81 publications

Stretching, Shaking, Inflating: Volcanic-Tectonic Interactions at a Rifting Silicic Caldera

Stretching, Shaking, Inflating: Volcanic-Tectonic Interactions at a Rifting Silicic Caldera

The Deep Basin and Underlying Basement Structure of the Tanganyika Rift

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