The sedimentary succession of the eastern and northern Kaapvaal craton: an Archean analog of the Phanerozoic Canadian Cordillera?

Archean cratons are at the core, in terms of both their geographical position and geological processes, of the first long-lived lithospheric units. Shedding light on the temporality of craton formation is hence central to establishing geodynamic models accounting for the raising of emerged land masses and the consequential development of emerged life. To this extent, the Kaapvaal craton (KC), mostly exposed in South Africa and eSwatini, is ideally suited since it shows well-preserved rocks of both low and high-grade metamorphic rocks reflecting sedimentary, burial, metamorphic and magmatic processes occurring from ca . 3.5 Ga to ca . 2.5 Ga. In this study, we focus on meta -sedimentary rocks exposed in the northern edge of the KC (an area also known as the southern marginal zone, SMZ, of the Limpopo belt) that experienced granulite facies metamorphism at ca . 2.7 Ga. We conducted zircon U–Pb/Hf isotope analyses of both igneous and metamorphic domains. Our results indicate that the Hf-isotope signature of igneous zircon domains from these high grade meta -sedimentary rocks is similar to the Hf-isotope signatures of coeval igneous zircon located further south and unambiguously distinct from that of the Central zone of the Limpopo belt. We interpret these observations, along with other lines of evidence, as indicating that the SMZ is genetically related to the northern KC and share limited connection, if any, with the central zone of the Limpopo belt before 2.6 Ga. Further, our new results, in combination with published zircon U–Pb/Hf isotope analyses from (meta)-igneous and meta -sedimentary rocks, illuminate the tectonic evolution of the KC, with migration of the orogenic front marked by successive closure of sedimentary basins from South to North between 3.5 Ga and 2.85 Ga. This is consistent with an accretionary-type orogen geodynamic, similar to what is inferred for the Phanerozoic Canadian Cordillera.