The Mwembeshi Shear Zone is a ductile

shear zone In geology, a shear zone is a thin zone within the Earth's crust or upper mantle that has been strongly deformed, due to the walls of rock on either side of the zone slipping past each other. In the upper crust, where rock is brittle, the shear ...

about 550 million years old that extends ENE-WSW across

Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most cent ...

. In Zambia, it separates the Lufilian Belt to the northwest from the

Zambezi Belt The Zambezi Belt is an area of orogenic deformation in southern Zambia and northern Zimbabwe. It is a segment of a broader belt lying between the Congo Craton and the Kalahari Craton, which also includes the Lufilian Arc and the Damaran Belt. The ...

to the southeast. It is associated with a sinistral strike slip movement. The Mwembeshi Shear Zone lies between the Congo craton to the NW and the Kalahari craton to the SE, to the west (in today's orientation) of the Mozambique Belt, which is on the north and east side of the Kalahari Craton. It was formed during the Pan-African orogeny when "North" and "South"

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

were amalgamated along the Kuunga orogeny zone between 580 Ma and 480 Ma. The date of around 550 Ma for the Mwembeshi shear zone is based on U-Pb zircon ages of syntectonic granites from the

Hook massif The Hook granite massif is a large formation in central Zambia formed around 550 million years ago during the Pan-African orogeny. It lies in the inner part of the Lufilian arc. Today, the south-western extension of the massif lies under the Kafue ...

and of associated

hypabyssal A subvolcanic rock, also known as a hypabyssal rock, is an intrusive igneous rock that is emplaced at depths less than within the crust, and has intermediate grain size and often porphyritic texture between that of volcanic rocks and plutonic roc ...

rhyolite. During the amalgamation there was sinistral

transpression In geology, transpression is a type of strike-slip deformation that deviates from simple shear because of a simultaneous component of shortening perpendicular to the fault plane. This movement ends up resulting in oblique shear. It is generally ve ...

along the boundary between the Kalahari craton and the Congo and Tanzanian cratons (which had already amalgamated), which is now expressed as the Mwembeshi Shear Zone. The sinistral sense shows that, in modern coordinates, the Congo-Sao Francisco Craton approached the remainder of southwestern Gondwana from the north, although at the time southwestern Gondwana was oriented about 90 degrees clockwise of today's orientation, and the Congo Craton approached from the east. There was little vertical displacement, but Mwembeshi is a major sinistral transcurrent shear zone. The shear zone accommodates a change in the structural vergence between the Zambezi Belt and the Lufilian Arc. Further to the southwest, the shear zone extends along part at least of the Damaran belt. There are known to be basic connections between geological terranes and mineralization models, so understanding the Mwembeshi Shear Zone is important to understanding where mineral resources may be found in the region. Despite this, as of 1990 there had been relatively little exploration.

References

;Citations ;Sources * * * * * Geology of Africa Seismic faults of Africa Shear zones {{palaeo-geo-stub