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

Abstract

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.

Boris Choubert: Unrecognized visionary geologist, pioneer of the global tectonics

“…Boris Choubert's vision of the orogenies of the whole Palaeozoic Era is summarized in Fig. 4, which is the first plate reconstruction for the Palaeozoic (Letsch, 2017). It is very similar to current models and, despite the progress made over the last 80 years, bears witness to the remarkable insight of its author.…”

“…4 (redrawn from Choubert's Fig. 3), which is "probably the first plate reconstruction for the Palaeozoic" (Letsch, 2017). Nevertheless, this series of maps only shows very small plate movements, outlined with arrows and thin grey continental contours, in spite of Choubert describing various continental movements in the accompanying text, sometimes in great detail.…”

“…It is not possible to attach this map to the present paper because it is protected by copyright. It has however been reproduced in a reduced size by Şengör (2014), by Letsch (2017) and more recently by Meinhold and Şengör (2018).…”

“…At that time, scientific publications did not circulate as easily as they do today! As already mentioned above, two papers were recently published simultaneously and independently (Letsch, 2017;Kornprobst, 2017). Their purpose was to highlight Boris Choubert's work on Precambrian and Palaeozoic mountain belts and continental drift.…”

Fifty years of the Wilson Cycle concept in plate tectonics: an overview

“…Furthermore, the title of Choubert's paper ('Research on the genesis of Paleozoic and Precambrian belts') did not reveal its full scientific content, and thus probably contributed to its lack of wider acknowledgement (Kornprobst 2017). Thankfully, in recent years this early work of Choubert has started to receive the recognition it deserves (Kornprobst 2017;Letsch 2017). Other notable contributions that pre-date the Plate Tectonic paradigm of the 1960s include Alexander Du Toit (1937) and Arthur Holmes (1931Holmes ( , 1944.…”