The Kenya rift revisited: insights into lithospheric strength through data-driven 3-D gravity and thermal modelling
We present three-dimensional (3-D) models that describe the present-day thermal and rheological state of the lithosphere of the greater Kenya rift region aiming at a better understanding of the rift evolution, with a particular focus on plume–lithosphere interactions. The key methodology applied is...
Main Authors: | , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-01-01
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Series: | Solid Earth |
Online Access: | http://www.solid-earth.net/8/45/2017/se-8-45-2017.pdf |
Summary: | We present three-dimensional (3-D) models that describe the present-day thermal and rheological
state of the lithosphere of the greater Kenya rift region aiming at a better
understanding of the rift evolution, with a particular focus on
plume–lithosphere interactions. The key methodology applied is the 3-D
integration of diverse geological and geophysical observations using gravity
modelling. Accordingly, the resulting lithospheric-scale 3-D density model is
consistent with (i) reviewed descriptions of lithological variations in the
sedimentary and volcanic cover, (ii) known trends in crust and mantle
seismic velocities as revealed by seismic and seismological data and (iii) the observed gravity field.
This data-based model is the first to image a 3-D
density configuration of the crystalline crust for the entire region of
Kenya and northern Tanzania. An upper and a basal crustal layer are
differentiated, each composed of several domains of different average
densities. We interpret these domains to trace back to the Precambrian
terrane amalgamation associated with the East African Orogeny and to magmatic
processes during Mesozoic and Cenozoic rifting phases. In combination with
seismic velocities, the densities of these crustal domains indicate
compositional differences.
The derived lithological trends have been used to
parameterise steady-state thermal and rheological models. These models
indicate that crustal and mantle temperatures decrease from the Kenya rift
in the west to eastern Kenya, while the integrated strength of the
lithosphere increases. Thereby, the detailed strength configuration appears
strongly controlled by the complex inherited crustal structure, which may
have been decisive for the onset, localisation and propagation of rifting. |
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ISSN: | 1869-9510 1869-9529 |