Résumé
Palaeomagnetic behaviour during the Ediacaran–Cambrian is problematic, with many discordant directions, suggesting a non-uniform magnetic field during the development of the first complex life on Earth c. 540 Myr ago. To better understand the global nature of such discrepancies, we provide new geochronological and palaeomagnetic data from the Parauapebas dyke swarm (6.10° S, 49.76° W), located in the southeastern Amazonian Craton (Carajás Province), Brazil. U–Pb dating on apatite and Ar–Ar whole-rock ages from different dykes give an emplacement date for this mafic dyke swarm of c. 522 Ma. Most of the sites revealed a stable characteristic remanent magnetization with Dm = 290.6° and Im = −42.4° (N = 15, k = 8, a95 = 14.4°), yielding a palaeomagnetic pole for Amazonia at 21.8° S, 14.4° E (K = 8.3, A95 = 14.1°). The primary origin of this pole is confirmed by a positive baked contact, the petrography and magnetic mineralogy experiments. Yielding an R criterion of 6, this is the first reliable pole for Amazonia during the Cambrian. Although a persistent anomalous magnetic field since the Ediacaran cannot be dismissed with the available dataset, such discrepancies could be attributed to uncertainties in global reconstructions or data-related issues. Without additional constraints, a Cambrian geocentric axial dipole may be considered.