Tectonic model for the evolution of the Limpopo Belt

Proterozoic Transpressive Deformation in the Northern Marginal Zone, Limpopo Belt, Zimbabwe

“…In contrast, no age-Z pattern in hornblende was observed in the southeastern block (i.e., the Triangle shear zone), and farther south in the Central Zone of the Limpopo Belt biotites yield Rb/Sr ages of 1.97 Ga, only 0.03 Ga younger than the peak of metamorphism (Barton and van Reenen 1992;Kamber et al 1995). Together, these data suggest much faster cooling to the south, which compresses the cooling-age interval below analytical resolution.…”

“…In our samples, Z ranges from 36.7% to 37.8%; the extreme values correspond to a 41 + 9 K difference in the model Rb/Sr biotite ages in the Central Zone to the south of this Proterozoic structure yield 1.97 Ga, only 30 m.y. younger than peak metamorphism (Barton and van Reenen 1992;Kamber et al 1995).…”

“…Existing models for the Limpopo Belt can be classified into those that do not recognize the importance of the strike-slip movement on the Triangle shear zone (e.g., Roering et al 1992;Windley et al 1993) or those that attribute an incorrect Archean age to this deformation (e.g., McCourt and Vearncombe 1992;Treloar et al 1992). None of the models has realized the important uplift of the Central Zone associated with this movement.…”

“…Van Breemen and Hawkesworth (1980) found evidence for garnet growth under granulite facies conditions at 1.98 Ga in the boundary between the Central Zone and the Northern Marginal Zone, but such Proterozoic deformation was regarded as late reactivation of a primary late Archean feature by McCourt and Vearncombe (1992). Roering et al (1992) pointed out difficulties with the McCourt and Vearncombe model, although they also regarded the Central Zone as allochthonous. They considered the contact between the Central Zone and the Northern Marginal Zone to be a thrust.…”

Conflicting P–T paths within the Central Zone of the Limpopo Belt: A consequence of different thermobarometric methods?

“…2.0 Ga (Kamber et al 1995; Holzer et al, 1995;Holzer et al, 1998;Kroner et al 1999;Schaller et al 1999;Zeh et al 2004;Zeh et al, 2005a,b;Eriksson et al, 2009). Conversely, Van Reenen et al (1987), McCourt and Vearncombe (1992), Roering et al (1992), McCourt and Armstrong (1998), Bumby et al (2001), Bumby and Van der Merwe (2004) advocate that the CZ and the entire Limpopo Belt formed during a single, Neoarchean, high-grade event that was initiated by the collision of the Kaapvaal and Zimbabwe cratons. However, recent studies (Boshoff et al, 2006;Zeh et al, 2007;Perchuk et al, 2008;Van Reenen et al, 2008;Gerdes and Zeh, 2009;Millonig et al, 2008) have unequivocally demonstrated that parts of the CZ have undergone a series of complex and temporally-discrete events, which include the formation and subsequent anatexis of the Sand River Gneiss at 3.24-3.12 Ga (Zeh et al, 2007;Gerdes and Zeh, 2009), structural, metamorphic and magmatic events at 2.65-2.51 Ga (e.g.…”