Abstract Products of geological processes, such as rock formations, unconformities, structures, minerals, fossils and landforms, represent unique records of the evolution of the Earth. These form a coherent picture showing how the Earth evolved, but the picture becomes blurred with antiquity. Consequently, there are challenges in gathering information from the Archean, the period during which the foundations of the Earth were laid down. The 2.7 Ga Belingwe Greenstone Belt in Zimbabwe has proved to be valuable because it has some of the best-preserved Archean stratigraphy in the world. An unconformity between sialic basement and supracrustal rocks of the greenstone belt, and exotic rocks, such as komatiites and stromatolites, contributes immensely toward our knowledge of the evolution of the young Earth and the beginning of life. The frequent use of the Belingwe Greenstone Belt examples to explain geotectonic processes of the early Earth gives testimony to the importance of this structure. Interpretation of some of the features of the Greenstone Belt is sometimes controversial, which forms areas of endless research to better understand the Archean Era. It is for these reasons that arguments are presented for consideration of the Belingwe Greenstone Belt as a national geoheritage site.

Abstract The Neoarchean to Paleoproterozoic Betsiboka Suite of Madagascar mainly consists of granitoid orthogneiss and migmatite variably metamorphosed to amphibolite and granulite facies during the late Neoproterozoic. New U–Pb zircon data yield emplacement ages of 2512 ± 17, 2507 ± 17, 2493 ± 14 and 2485 ± 16 Ma. Zircon δ 18 O data indicate involvement of the continental crust during magma genesis. Mostly positive ε Hf ( t ) values plot slightly below the depleted-mantle curve. The isotopic data favour mixing between an older Archean crustal source and a juvenile depleted-mantle source. Possible local crustal candidates for the older component in the exposed Malagasy basement are Neoarchean mafic gneisses in the Tsaratanana Complex and the c. 3200 Ma Nosy Boraha orthogneiss in the Antongil Domain. The new isotopic data support interpretations from previous studies investigating the genesis of Tonian plutonic rocks advocating crustal melting of a Mesoarchean crustal source in the Antananarivo Domain. In addition, detrital zircon in the Proterozoic Ambatolampy Group and Itremo Group probably had a local source with the same isotopic composition as the Betsiboka Suite. Our study demonstrates the significance of multi-isotopic data from zircon for constraining the sources of detrital zircon grains in sedimentary provenance studies.