Abstract In his book De Civitate Dei (published about 424), Saint Augustine reported the discovery, on the shore of Utica (now Tunisia), of an enormous tooth, which he attributed to a giant. In Europe, this finding reinforced the myth of the past existence of giants on Earth, mentioned in the Bible. In 1630, new relicts of a so-called giant were found at Utica. Thomas d'Arcos, who lived in Tunis, described them and sent a tooth to the French scholar Peiresc, who demonstrated that it belonged to an elephant instead. Peiresc knew that he was contradicting Saint Augustine, but, while Galileo was under trial in Rome, he remained silent on this matter. Based on a sketch, the tooth can be attributed to an African elephant close to the present species Loxodonta africana or to the Pleistocene L. africanava . Peiresc also investigated other similar finds, particularly that of the so-called giant Theutobochus, discovered in 1613 at Montrigaud in France (in reality, a Miocene Deinotherium giganteum ), and that of ‘giants’ in Sicily and Puglia (Italy). In each case, Peiresc attributed the relicts to the ‘grave of an elephant’ instead of a giant. However, his studies did not dispel the myth of giants, which persisted until the 18th century.

Abstract Central Hoggar, within the Tuareg shield to the east of the West African craton, is known for its complexity owing to the interplay of the Eburnean and Pan-African orogenies. The Tidjenouine area in the Laouni terrane belongs to the LATEA metacraton and displays spectacular examples of granulite-facies migmatitic metapelites. Here, we present a detailed petrological study coupled with in situ U–Pb zircon dating by laser-ablation inductively coupled plasma mass spectrometry (ICP-MS) that allows us to constrain the relative role of the Eburnean and Pan-African orogenies and hence to constrain how the LATEA Eburnean microcontinent has been partly destabilized during the Pan-African orogeny; that is, its metacratonic evolution. These metapelites have recorded different metamorphic stages. A clockwise P–T evolution is demonstrated on the basis of textural relationships, modelling in KFMASH and FMASH systems and thermobarometry. The prograde evolution implies several melting reactions involving the breakdown of biotite and gedrite. Peak metamorphic P–T conditions of 860±50 °C and 7–8 kbar (M 1 ) were followed by a decrease of pressure to 4.3±1 kbar and of temperature to around 700 °C, associated with the development of migmatites (M 2 ). After cooling, a third thermal phase at c . 650 °C and 3–4 kbar (M 3 ) occurred. U–Pb zircon laser ablation ICP-MS analysis allows us to date the protolith of the migmatites at 2151±8 Ma, the granulite-facies and migmatitic metamorphisms (M 1 –M 2 ) at 2062±39 Ma and the medium-grade metamorphic assemblage (M 3 ) at 614±11 Ma. This last event is coeval with the emplacement of large Pan-African granitic batholiths. These data show that the main metamorphic events are Eburnean in age. The Pan-African orogeny, in contrast, is associated mainly with medium-grade metamorphism but also mega-shear zones and granitic batholiths, characterized by a high temperature gradient. This can be considered as typical of a metacratonic evolution.