Abstract This paper presents the investigation of fraud and of the theft of metal acquired by a Brazilian company from a Chinese supplier. Zinc ingots were transported by ship from China to the city of Londrina, in Paraná State, Brazil. However, they were substituted at some point during their journey, and replaced with bags containing fine crushed rock. In this case of a classic ‘substitution’ it was possible to use geological methods to investigate the crushed rock. As such, the mineralogical, petrological and isotope analysis showed the replaced rock did not originate from a Brazilian provenance. Therefore, the substitution possibly occurred before the cargo's arrival in Brazil. An inadequate chain of custody of the cargo, during transportation from Asia to Brazil, including the onward journey from Paranaguá to Londrina, is likely to have provided the opportunity for the material exchange to take place. Collaboration between the Brazilian Federal Police and geological experts based in academia enabled the crime to be investigated and solved.

Abstract This chapter presents a synthesis of the pre-break-up plate tectonics of western Gondwana and the pre- and syn-rift magmatism in the SW South Atlantic margin (Brazil, Uruguay and Argentina) and the conjugate African continental margin (Angola, Namibia and South Africa). An updated database of the geographical locations of the primary available radiometric ages is also included in this work. A systematic analysis of the K–Ar and Ar/Ar ages from outcrops and boreholes shows a marked Mid to Late Jurassic peak in the southernmost segment of the South Atlantic, related to the emplacement of the Karoo volcanics in South Africa and in Argentina (including the Falkland Islands), and an important Early Cretaceous peak with age distributions that are related to the Gondwana break-up and formation of rift basins along the incipient continental margins. In both the southern Brazilian and Argentinian margins, as well as in the conjugate Namibian and South African margins, several igneous centres and basaltic lava flows are suggestive of the influence of mantle plumes in the Early Cretaceous, which were heralded by mafic dyke swarms in Argentina, Brazil, South Africa and Namibia. Supplementary material: A complete table with Radiometric ages of Jurassic–Early Cretaceous magmatism in the southern portion of West Gondwana is available at: www.geolsoc.org.uk/SUP18589