Revisiting the paleomagnetism of the neoarchean Uaua mafic dyke swarm, Brazil : implications for archean supercratons

The original connections of Archean cratons are becoming traceable due to an increasing amount of paleomagnetic data and refined magmatic barcodes. The Ilaua block of the northern Sao Francisco craton may represent a fragment of a major Archean craton. Here, we report new paleomagnetic data from the 2.62 Ga-Vaud tholeiitic mafic dyke swarm of the Uatia block in the northern Sao Francisco craton, Eastern Brazil. Our paleomagnetic results confirm the earlier results for these units, but our interpretation differs. We suggest that the obtained characteristic remanent magnetization for the 2.62 Ga swarm is of primary origin, supported by a provisionally-positive baked contact test. The corresponding paleomagnetic pole (25.2 degrees N, 330.5 degrees E, A(95) = 8.1 degrees, N = 20) takes the present northern part of the Sao Francisco craton to moderate latitudes. Based on the comparison of the paleolatitudes of cratons with high-quality paleomagnetic data and magmatic barcodes, we suggest that the northern part of the Sao Francisco craton could have been part of the proposed Supervaalbara supercraton during the Archean. Supervaalbara is proposed as including (but not limited to) the part of the Sao Francisco craton as well as the Superior, Wyoming, Kola + Karelia, Zimbabwe, Kaapvaal, Tanzania, Yilgarn, and Pilbara cratons329108123FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2012/15824-6We would like to thank the editor Randall Parrish, the guest editors Mike Hamilton and Richard Ernst, and two anonymous reviewers for their comments which significantly improved our manuscript. The work of JS was funded by the Academy of Finland. This publication contributes to IGCP648 Supercontinent Cycles & Global Geodynamics. Fieldwork for the dyke sampling was funded by São Paulo State Research Foundation (FAPESP), Brazil, through the thematic project “Evolution of Archean Terranes of the São Francisco Craton and the Borborema Province, Brazil: global environmental and geodynamic implications” (grant # 2012/15824-6 to EPO), and by the National Science Foundation (USA) grant EAR-1149434 “Reading magnetic fingerprints from deep time: an insight into the geodynamo and early Earth system evolution” (to AS