Geodynamic significance of the TRM segment in the East African Rift (W-Tanzania): Active tectonics and paleostress in the Ufipa plateau and Rukwa basin

Delvaux, Damien; Kervyn, F.; Macheyeki, Athanas S.; Temu, E.B.

doi:10.1016/j.jsg.2012.01.008

Cited by 100 publications

(97 citation statements)

References 69 publications

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“…Our ϕ ¼ 30°, α ¼ −30°models thus seem to fit the natural example, but the interpretation of the TRM fault zone as a dextral strike-slip zone is challenged by an orthogonal opening model, in which all rift basins form due to extension perpendicular to the rift trends (Morley, 2010;Delvaux et al, 2012). Field evidence indicates that the steep rift boundary faults of the Rukwa Basin are indeed rather normal or dip-slip faults instead of strike-slip faults.…”

Section: Tanganyika-rukwa-malawi Fault Zonementioning

confidence: 72%

How oblique extension and structural inheritance influence rift segment interaction: Insights from 4D analog models

Zwaan

Schreurs

2017

Interpretation

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Rifting of the continental lithosphere involves the initial formation of distinct rift segments, often along preexisting crustal heterogeneities resulting from preceding tectonic phases. Progressive extension, either orthogonal or oblique, causes these rift segments to interact and connect, ultimately leading to a full-scale rift system. We study continental rift interaction processes with the use of analog models to test the influence of a range of structural inheritance (seed) geometries and various degrees of oblique extension. The inherited geometry involves main seeds, offset in a right-stepping fashion, along which rift segments form as well as the presence or absence of secondary seeds connecting the main seeds. X-ray computer tomography techniques are used to analyze the 3D models through time, and results are compared with natural examples. Our experiments indicate that the extension direction exerts a key influence on rift segment interaction. Rift segments are more likely to connect through discrete fault structures under dextral oblique extension conditions because they generally propagate toward each other. In contrast, sinistral oblique extension commonly does not result in hard linkage because rift segment tend to grow apart. These findings also hold when the system is mirrored: left-stepping rift segments under sinistral and dextral oblique extension conditions, respectively. However, under specific conditions, when the right-stepping rift segments are laterally far apart, sinistral oblique extension can produce hard linkage in the shape of a strike-slip-dominated transfer zone. A secondary structural inheritance between rift segments might influence rift linkage, but only when the extension direction is favorable for activation. Otherwise, propagating rifts will simply align perpendicularly to the extension direction. When secondary structural grains do reactivate, the resulting transfer zone and the strike of internal faults follow their general orientation. However, these structures can be slightly oblique due to the influence of the extension direction. Several of the characteristic structures observed in our models are also present in natural rift settings such as the Rhine-Bresse Transfer Zone, the Rio Grande Rift, and the East African Rift System.

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Section: Tanganyika-rukwa-malawi Fault Zonementioning

confidence: 72%

How oblique extension and structural inheritance influence rift segment interaction: Insights from 4D analog models

Zwaan

Schreurs

2017

Interpretation

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“…The Ubendian Belt was reactivated several times, preserving geochronologic, petrographic, and geochemical evidence of successive terrane accretion (e.g., Boniface et al, ; Boniface & Schenk, ; Lenoir et al, ). Known terranes within the Ubendian Belt are separated by shear zones which include the Mughese Shear Zone, the Mtose Shear Zone (Figure ; Daly, ; Delvaux et al, ), and the Chisi Suture Zone which represents the major suture zone between the Precambrian Tanzania Craton and the Bangweulu Block (Boniface & Schenk, ; Lemna et al, ). Several studies have highlighted the role of these shear zones in fault development and the distribution of seismicity in southern Tanzania and northern Malawi (e.g., Camelbeeck & Iranga, ; Dawson et al, ; Delvaux et al, ; Kolawole et al, ; Lemna et al, ; Morley et al, ; Morley, ).…”

Section: Geologic Settingmentioning

confidence: 99%

Controls of Basement Fabric on the Linkage of Rift Segments

et al. 2019

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The Rukwa and North Malawi Rift Segments (RNMRS) both define a major rift‐oblique segment of the East African Rift System and are often regarded as discrete rifts due to the presence of the uplifted Mbozi block between them. Here we investigate the influence of basement fabrics on the coupling and linkage of border faults across an interrift transfer zone between discrete juvenile rift segments. We utilized satellite digital elevation model to investigate the morphological architecture of the rift domains and aeromagnetic data to assess the relationships (plan view) between the rift structures and the prerift basement fabrics. Our results show that the present‐day morphology of the RNMRS is characterized by along‐rift alternation of rift shoulder polarity, characteristic of coupled rift segments. Interpretation of filtered aeromagnetic maps along the boundaries of the RNMRS reveals striking alignment of the rift‐bounding faults with colinear NW‐SE trending preexisting basement fabrics. We find that rift coupling along the NE boundary of the Mbozi transfer zone is accommodated by fault‐assisted magma plumbing, whereas coupling along the SW boundary is accommodated by strike‐slip and oblique‐normal faulting that reactivated the Proterozoic Mughese shear zone, within the collisional boundary between the Tanzania craton and the Bangweulu cratonic block. Further, we show how the configuration of the basement fabrics may influence the formation of rift bifurcation across inter‐rift transfer zones. We suggest that the structural connectivity of the boundary faults along the RNMRS and their alignment with colinear basement fabrics demonstrate the influence of structural inheritance on the amalgamation of approaching rift segments.

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“…However, Link et al (2010) describe a D4 event that represents the Mesoproterozoic Kibaran orogeny, which may correspond with the D5 presented here or even the D6 brittle reverse faulting that we find. Delvaux et al (2012) describe a late Panafrican compression event and a Triassic strike slip event in the Rukwa rift, which may correspond to the D6 event that we find in the Albertine rift.…”

Section: Discussionmentioning

confidence: 55%

The Rwenzori Mountains, a Palaeoproterozoic crustal shear belt crossing the Albertine rift system

Koehn

Link²,

Sachau³

et al. 2015

Int J Earth Sci (Geol Rundsch)

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the development of steep shear zones with a NNE-SSW and SSE-NNW trend including the large Nyamwamba shear followed by a local D5 retrograde event and D6 brittle reverse faulting. The Palaeoproterozoic Buganda-Toro belt is relatively stiff and crosses the NNE-SSW running rift system exactly at the node where the highest peaks of the Rwenzori Mountains are situated and where the Lake George rift terminates towards the north. Orientation of brittle and ductile fabrics show some similarities indicating that the cross-cutting Buganda-Toro belt influenced rift propagation and brittle fault development within the Rwenzori Mountains and that this stiff belt may form part of the reason why the Rwenzori Mountains are relatively high within the rift.

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Geodynamic significance of the TRM segment in the East African Rift (W-Tanzania): Active tectonics and paleostress in the Ufipa plateau and Rukwa basin

Cited by 100 publications

References 69 publications

How oblique extension and structural inheritance influence rift segment interaction: Insights from 4D analog models

How oblique extension and structural inheritance influence rift segment interaction: Insights from 4D analog models

Controls of Basement Fabric on the Linkage of Rift Segments

The Rwenzori Mountains, a Palaeoproterozoic crustal shear belt crossing the Albertine rift system

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