Limpopo magma-rich transform margin (South Mozambique), implications for the Gondwana breakup
Abstract
The continental rifted margins of Mozambique provide an excellent example of
continental passive margins with a significant structural variability associated to
magmatism and inheritance. Despite accumulated knowledge in this area, the tectonic
structure and nature of the crust from Mozambique margins, especially the Limpopo
transform margin are still poorly known. Here, we use high-resolution seismic
reflection dataset and wells from industry to propose a structural interpretation of this
area.
Our results indicate that the Limpopo transform fault zone limits a continental crust
westward, with deep Karoo grabens, from an oceanic crust domain eastward. The
Limpopo transform margin also shows a widespread magmatism, attested by the
presence of lava flows and highly magmatic oceanic crust, implying different thermal
perturbations through time and space.
We suggest that the expression of thermal perturbations started with the Karoo Large
Igneous province emplacement at about 180 Ma. This intense magmatism event is
favored by pre-existing and neo-formed faults, which may contribute significantly to the
distribution of magma generated. We propose an evolution model from the onset of the
rifted margin to the seafloor spreading along the Limpopo magma-rich transform
margin with (i) an E-W extension trend responsible for the formation of a large faultcontrolled
basin during the Permo-Trias (T1); (ii) the extension becoming NNW-SSE,
oblique to the margin direction as attested by the presence of flower structures, allows
for reactivation of previous structures inducing the deposition of a volcanosedimentary
wedge, and the formation of several magmatic infilling during the Jurassic
(T2); (iii) the onset of oceanic spreading after ca. M25 (i.e. 156 Ma) in the Limpopo area
which triggered the uplift and erosion of the proximal parts of the margin as well as the
formation of several other magmatic infilling (T3).