A pioneer of Precambrian geology: Boris Choubert's fit of the continents across the Atlantic (1935) and his insights into the Proterozoic tectonic structure of the West African Craton and adjacent areas

Plate tectonics revolutionized the Earth Sciences during the 1960s and led to a fundamentally new view of tectonic processes inside mountain belts. Application of the new theory to pre-Permian and especially Precambrian orogenic belts developed somewhat reluctantly during the 1970s and 1980s. The present article presents and discusses the ideas of Boris Choubert (1906-1983), a French colonial geologist of Russian origin, which he first developed in 1935. He tried to test Wegener's theory of continental displacement (a forerunner of plate tectonics) by applying it to Paleozoic and Precambrian orogenic belts around the Atlantic (a topic altogether neglected by Wegener). To achieve this, he produced a fit of the continents across the Atlantic which is almost identical to the famous 1965 fit of Bullard et al. Starting from this Paleozoic continental configuration, he presented an inter-continental synthesis of Precambrian geology and discussed problems from a wide array of topics, ranging from regional tectonics of the West African Craton, questionable Precambrian fossils, tillites (and cap carbonates) to the supposed origin of detrital diamonds in Gabon and Brazil. He also provided probably the first Precambrian plate reconstruction avant la lettre. After his 1935 paper, Choubert worked for decades in Africa and South America and had opportunity to test and refine his synthesis. His example is a call, addressed to present-day geologists working on Precambrian geology in Africa and other regions, to consult the old colonial literature which contains a wealth of factual information and theoretical inspiration which is still of interest today.