Neoarchean to paleoproterozoic evolution of the polymetamorphic central zone of the Limpopo Complex

Integrated geological studies in the Central Zone of the Limpopo Complex formed the basis for the construction of a composite deformation (D)-pressure (P)- temperature (T)-time (t) (D-P-T-t) diagram that shows the following: First, in the Neoarchean the Central Zone probably underwent high-pressure (HP) (P >14 kbar, T ∼950 °C) conditions followed by near isothermal decompression to ultrahightemperature conditions (UHT) (T ∼1000 °C, P ∼10 kbar), before ca. 2.68 Ga. Second, the post-peak exhumation history linked to two distinct decompression cooling stages commenced at ca. 2.68 Ga and ended before the emplacement of the Bulai Pluton at ca. 2.61 Ga. Stage 1 started at P ∼9 kbar, T = 900 °C, and culminated with the emplacement of leucocratic anatectic granitoids at ca. 2.65 Ga. Stage 2, linked to the development of major SW-plunging sheath folds and related shear zones, started at P ∼6 kbar, T ∼700 °C and ended at P ∼5 kbar, T ∼550 °C, before ca. 2.61 Ga. The rocks resided at the mid-crustal level for more than 600 m.y. before they were again reworked at ca. 2.02 Ga by a Paleoproterozoic event. This event commenced with isobaric (P ∼5 kbar) reheating (T ∼150 °C) of the rocks related to the emplacement at ca. 2.05 Ga of magma linked to the Bushveld Igneous Complex. This was followed by fi nal exhumation of the Central Zone. The Neoarchean high-grade event that affected the Limpopo Complex is linked to a Himalayan-type collision of the Kaapvaal and Zimbabwe Cratons that resulted in over-thickened unstable crust and the establishment of HP and UHT conditions. This unstable crust initially responded to the compressional event by thrust-driven uplift and spreading of the marginal zones onto the two adjacent granite-greenstone cratons. The post-peak exhumation history was probably driven by a doming-diapiric mechanism (gravitational redistribution).