Structure et propagation d'un rift magmatique en bordure de craton : approche intégrée de la divergence Nord-Tanzanienne par analyse des populations de failles et du réseau de drainage

Abstract : Any kinematic model applied to the southerly-propagating and diverging South Kenya rift (SKR) should necessarily integrate the structure of the Magadi-Natron axial trough (previous studies), but also those of the Oldoinyo Ogol (OOB) offset block to the west. Our work is chiefly based on SRTM 30 m satellite imagery analysis, and allows us (1) to precise the morphostructural arrangement of the entire SKR,(2) to identify 2 successive border faults systems, (3) to emphasize the role of the Ol Doinyo Ogol master fault, (4) to elaborate a 2-stage rift model (7-3 Ma et <3 Ma), and (5) to attribute a key-role to a transverse Proterozoic discontinuity on the lateral shift of the OOB, as well as on the split of the rift into the Eyasi rift arm and on the off-axis location of the early Crater Highlands magmatic segment, hence demonstrating the importance of basement structural inheritance on rift kinematics.The quantitative analysis of fault populations shows the restricted nature of most intra-rift faults, and leads us to precise the spatiotemporal evolution of extension from a stage of localized strain (border faults) to a stage of diffuse extension (<3 Ma).From the analysis of the river drainage extracted from the basement uplifted block bounding the rift system to the west, it is assumed that (1) lithological and tectonic basement features exerted a strong control on the river network, (2) fault-related basement uplift is polyphased, and (3) the unsteady nature of the present-day river drainage is due to still active rift-flank uplift in the southern portion of the rift system.
Document type :
Theses
Complete list of metadatas

Cited literature [569 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02271928
Contributor : Abes Star <>
Submitted on : Tuesday, August 27, 2019 - 12:45:08 PM
Last modification on : Wednesday, August 28, 2019 - 1:16:23 AM

File

These-2018-SML-Geosciences_mar...
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02271928, version 1

Collections

Citation

Remigius Gama. Structure et propagation d'un rift magmatique en bordure de craton : approche intégrée de la divergence Nord-Tanzanienne par analyse des populations de failles et du réseau de drainage. Sciences de la Terre. Université de Bretagne occidentale - Brest; University of Dar es Salaam, 2018. Français. ⟨NNT : 2018BRES0047⟩. ⟨tel-02271928⟩

Share

Metrics

Record views

79

Files downloads

12