100 Years of Research on the West African Craton

Journal of African Earth Sciences xxx (2015) 1e5

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Journal of African Earth Sciences

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Editorial 100 years of research on the West African Craton

The West African Craton extends across 14 countries inwestern Af- including UNESCO, the Commission for the Geological map of the rica, and consists of two Archean nuclei in the north-western and World, the World Bank and the European Union, we have seen a south-western parts of the craton juxtaposed against an array of Pale- diverse range of country-level and regional research and data inte- oproterozoic domains made up of greenstone belts, sedimentary ba- gration programs (Fig. 2). In 1991, the IGCP 233 “The West African sins, regions of extensive granitoid-TTG plutons and large shear zones, Orogens and Circum-Atlantic Correlatives” produced a volume which are overlain by Neoproterozoic and younger sedimentary ba- that presented the state of our knowledge on many aspects of the sins. The borders of the WAC are largely defined by a combination geology and metallogenesis of the WAC at the time (Dallmeyer of surface geology and gravity signatures (Burke and Whiteman, and Lecorch e, 1991; editors). More recently, in 2003e2007, the 1973; Roussel and Lesquer, 1991; Ennih and Liegeois, 2008a, b). IGCP 485 “The boundaries of the West African craton” focused on The earliest surviving geology maps from Africa, or any conti- the peculiar events occurring at craton margins (metacratonic nent, date back to a map of a sandstone quarry, gold mine and set- areas), favoured intra-Africa mobility of African geologists and pro- tlement at Bir Umm Fawakhir, Egypt (Scribe-of-the-Tomb duced a volume (Ennih and Liegeois, 2008a, b; editors) of >500 Amennakhte, son of Ipuy, 1160 BC; Harrell and Brown, 1992) and pages and 25 papers demonstrating the interest in the geology show the local distribution of mines, mineralised occurrences and and metallogeny of the WAC boundaries. transport routes, which find an echo in the of the Keni eba region Immediately following the independence of the first African col- of Senegal some thirty centuries later (Vincent and Delmare, onies, the Economic Commission for Africa commissioned a report 2015). Although earlier small scale geological maps exist for West by Frank Dixey (then Presidentof the Association ofAfrican Geological Africa (e.g. Lenz, 1882), it was the undertaking prior to 1920 of sys- Surveys) entitled “Geology, Applied Geology (Mineral Resources) and tematic 1:M geological mapping by Henry Hubert, a French Gov- Geophysics in Africa”, as part of a wider review of the natural re- ernment official working in French West Africa (and a founding sources of the African continent (UNESCO, 1963). This report high- member of the Commission for the Geological map of the World) lighted a series of challenges facing the African geological surveys that culminated in the 1934 publication of the 1:6 M regional and the minerals industry that was actively exploring on the conti- map that first shows a recognisable pattern of the distribution of nent. The African Mining Vision, released in 2009, (together with cratonic rocks and overlying basins that carries through to today's the AMV Action Plan, 2012 and the Country Mining Vision, 2014) maps, including the work described in this special volume on the are a logical continuation of this earlier work. The AMV recognises Tectonics, Metallogeny of the West African Craton (Fig. 1; Hubert, the need for collaboration between the various stakeholders in the Af- 1934). The same year, the Gold Coast Geological Survey published rican minerals sector in its action plan (African Union Commission a map of southern Ghana at 1:500,000 scale that is even more pre- 2011) and states that critical success factors include the development cise, for this smaller region, and locates many of the gold deposits of mutually beneficial partnerships between the state, the private which have since been exploited (Junner, 1934). The involvement sector, civil society, local communities and other stakeholders, as of Henry Hubert also involved his support for the creation of a colo- well as a comprehensive knowledge of its mineral endowment. nial research organisation which was founded in 1942 as the “Ser- Eleven of the thirteen articles in this volume were funded vice de Recherches Scientifiques Coloniales” and which was a directly or indirectly by the AMIRA International West African precursor to the Institut de Recherche pour le Developpement, Exploration Initiative (WAXI). WAXI is an ongoing publiceprivate- one of the key partners in the West African Exploration Initiative, partnership that provides graduate and professional training as a a publiceprivate-partnership that has supported the research result of direct industry and partner government financial support. described in many of the papers in this volume. Since its inception in 2006 the WAXI program has undertaken From the early maps of Hubert, through systematic mapping research activities via a long-standing partnership between West campaigns by colonial and postcolonial geological surveys and mu- African and international academic partners, West African geolog- seums, (notably the Bureau de Recherches Geologiques et Minieres, ical surveys and local training centres such as Teng Tuuma Geoser- the British Geological Survey and the Bundesandstalt für Geowis- vices (TTG) in Burkina Faso. senchaffen und Rohstoffe: the French, British and German surveys The thirteen articles in this special issue fall into three main respectively; and geophysical acquisition programs led by the pre- classes and cover many parts of the West African Craton (Fig. 3), cursor to the Institut de Recherche pour le Developpement) to to- as follows. day's data acquisition, supported by transnational organisations Local or craton-scale geological studies.

Please cite this article in press as: Jessell, M.W., Liegeois, J.-P.100 years of research on the West African Craton, Journal of African Earth Sciences (2015), http://dx.doi.org/10.1016/j.jafrearsci.2015.10.008 2 Editorial / Journal of African Earth Sciences xxx (2015) 1e5

Fig. 1. Geological map of French West Africa and Togo by Hubert, 1934. 1:6 M Scale. This map is based on a compilation of 1:1 M scale map sheets produced over the preceding 20 years.

Baratoux et al., 2015- A new litho-structural framework geophysical data and ﬁeld mapping. Overprinting relationships for the Gaoua region, Burkina Faso, a region that hosts the suggest that copper mineralization is associated with the ﬁrst copper mineralization in Gongondy, Dienemera and Mt Biri deformation event, characterized by EeW trending structures copper deposits, based on the integration of high-resolution related to NeS shortening.

Fig. 2. Geoscience data acquisition and integration initiatives in West Africa and Africa since 1980. The release dates of the three documents related to the African Mining Vision published by the African Union are also noted (African Union, 2009, 2012; AMDC, 2014).

Please cite this article in press as: Jessell, M.W., Liegeois, J.-P.100 years of research on the West African Craton, Journal of African Earth Sciences (2015), http://dx.doi.org/10.1016/j.jafrearsci.2015.10.008 Editorial / Journal of African Earth Sciences xxx (2015) 1e5 3

Fig. 3. Map of the West African Craton with location of studies in this special issue. The dashed line shows the approximate modern margin of the West African Craton (Jessell et al., 2015a). The Jessell et al. paper on maﬁc dykes extends across the whole craton. Geological map of West Africa showing the ages of the major terranes, modiﬁed from the Geological Survey of Canada 1:35M map of the world (Chorlton, 2007). Reference for Chorlton: Chorlton, L.B., 2007. Generalized Geology of the World: Bedrock Domains and MajorFaults in GIS Format; Geological Survey of Canada, Open File 5529, 1 CD-ROM.

Diene et al., 2015- Review of gold mineralisation styles unconformity that defines the basal contact of the Birimian associated with the Senegal-Mali Shear zone in the context Supergroup. of ground geochemical and airborne geophysical data sets. The Villeneuve et al., 2015- Tectonic analysis of the Souttoufide belt, concentration of synvolcanic felsic rocks, fault, Morocco, and its relationship to the adjacent Mauritanides and and Au mineralisation within the SMSZ suggest that it repre- Anti-Atlas belts. The Souttoufide belt is a polyorogenic belt sents a synvolcanic structure or a series of structures which located at the margin of the WAC, including both Pan-African acted as conduits for magmatic and hydrothermal fluids and Variscan orogens similarly to the adjacent Anti-Atlas and and were reactivated during the subsequent deformation Mauritanides belts but with major peculiarities giving to the events. Souttoufides a great importance for the correlations between Hichem et al., 2015- 3D aeromagnetic and gravity data inversion the Appalachian and the West African belts. used to define major lineaments in the WAC of SW Algeria. The presence of the major faults throughout the continental crust Ore deposit descriptions. described in this work is an important argument to highlight that the domains located on both sides of the suture zone be- Amponsah et al., 2015- A structural, geochemical and met- tween the WAC and the mobile zone remained active since the allogenic analysis of the Julie gold deposit, NW Ghana. The Pan-African. Julie deposit is a rare case of granitoid (TTG)-hosted Jessell et al., 2015c- Craton-scale mapping of mafic dyke swarms mineralization. based on a combination of interpretation airborne magnetic Hein et al., 2015- Post-emplacement evolution of the Yatela gold datasets and previously mapped dykes. There are up to 5 deposit, western Mali. The combined mineralogical, textural and different dyke orientations found locally in many parts of the petrographic study of residuum samples, together with whole craton, and we this work demonstrates that there is a long and rock and detrital zircon geochronology have established a pro- complex history of mafic magmatism across the craton, with as cess of formation beginning in the Palaeoproterozoic followed an upper limit up to 26 distinct dyke swarms mapped based on by deposition of these recycled sedimentary units between 1114 their orientation and location. Ma and ca 700e750 Ma. Tshibubudze et al., 2015- Tectonic and magmatic evolution of Perrouty et al., 2015- A structural and metallogenic analysis of the Oudalan-Gorouol belt, Burkina Faso, based on field map- the Wassa gold deposit, SW Ghana. From its early timing and its ping and analytical studies of magmatic units. These studies associated mineral assemblage, this style of mineralization have defined the presence of a gneiss basement termed the constitutes a reasonable candidate for the source of the Tarkwa Lilengo gneiss complex, with recognition of an angular placer gold.

Please cite this article in press as: Jessell, M.W., Liegeois, J.-P.100 years of research on the West African Craton, Journal of African Earth Sciences (2015), http://dx.doi.org/10.1016/j.jafrearsci.2015.10.008 4 Editorial / Journal of African Earth Sciences xxx (2015) 1e5

Parra-Avila et al., 2015- Constraints on the timing of minerali- de Recherche pour le Developpement, the CNRS, the University of sation of the Wassa gold deposit, SW Ghana. The new age on Toulouse, the University of Montpellier II, the Dublin Institute the Wassa deposit is consistent with the possibility of an early for Advanced Studies, the University of Western Australia, the gold mineralizing vent during the Eoeburnean phase at ca. Czech Geological Survey, the University of the Witwatersrand, the 2191e2158 Ma. University of Ouagadougou, Macquarie University, the University of Ghana, the University of Bamako, UCAD). Regolith studies.

Arhin and Saeed, 2015- Coupled geochemical and regolith References mapping of units in complex regolith terrains of savannah re- African Union, 2009. Africa Mining Vision. gions of NW Ghana. This study identified four broad regolith African Union, 2012. African Development for Africa Action Plan for Implementing classes using the major oxides and concludes that mineral the AMV. exploration companies use weight proportions of K/Al and Mg/ AMDC, 2014. Country Mining Vision, Domesticating the Africa Mining Vision. Amponsah, P.O., Salvi, S., Beziat, D., Siebenaller, L., Baratoux, L., Jessell, M.W., 2015. Al ratios to characterise different regolith types to support the Geology and Geochemistry of the Shear-hosted Julie Gold Deposit, NW Ghana. field identification of the different regolith materials in complex http://dx.doi.org/10.1016/j.jafrearsci.2015.06.013. regolith terrains. Arhin, E., Saeed, Z.M., 2015. Unravelling Regolith Material Types Using Mg/Al and K/ fi Al Plot to Support Field Regolith Identi cation in the Savannah Regions of NW Jessell et al., 2015b- Interpretation of regional geophysical Ghana, West Africa. http://dx.doi.org/10.1016/j.jafrearsci.2015.09.007. datasets to identify a major paleochannel incising Voltaian Baratoux, L., Metelka, V., Naba, S., Ouiya, P., Siebenaller, L., Jessell, M.W., Nare, A., Sediments in central Ghana. The integration of magnetic, Beziat, D., Salvi, S., Franceschi, G., 2015. Tectonic Evolution of the Gaoua region, fi Burkina Faso: Implications for The mineralization. http://dx.doi.org/10.1016/ radiometric and EM data sets de ne a 230 km long, 2 km wide j.jafrearsci.2015.xx.xxx. main channel, with 20 km wavelength and 10 km amplitude Burke, K., Whiteman, A.J., 1973. In: Tarling, D.H., Runcorn, S.K. (Eds.), Uplift, Rifting meanders. Published geomorphological studies suggest that the and the Breakup of Africa. In Implications of Continental Drift to the Earth Sci- e modern drainage pattern has been in place for at least 11 Ma, ences, 2. Academic, London, pp. 735 745. In: Burke, K. 2011. Plate Tectonics, the Wilson Cycle, and Mantle Plumes: Geodynamics from the Top. Annual Review and probably at least 45 Ma. of Earth and Planetary Sciences, Vol. 39, pp. 1e29. doi:10.1146/annurev-earth- Metelka et al., 2015- Spectral library of lithologies and their 040809-152521. weathered equivalents from SW Burkina Faso. The variation in Dallmeyer, R.D., Lecorche, J.P. (Eds.), 1991. The West African Orogens and Circum- Atlantic Correlatives, IGCP-project 233. Springer-Verlag, Berlin Heidelberg, spectral signatures implies that discrimination between the pp. 9e28, 405pp. sampled materials based on hyperspectral data analysis should Diene, M., Fullgraf, T., Diatta, F., Gloaguen, E., Gueye, M., Ndiaye, P.M., 2015. Review e be possible. The newly acquired spectral library provides pri- of the Senegalo-Malien Shear Zone System Timing, Kinematics and Implica- tions for Possible Au Mineralisation styles. http://dx.doi.org/10.1016/j.jaf mary information for the analysis of remote sensing data in rearsci.2015.05.004. West Africa. Ennih, N., Liegeois, J.-P. (Eds.), 2008a. The Boundaries of the West African Craton (IGCP485), Geological Society of London Special Publication 297, p. 534. Ennih, N., Liegeois, J.P., 2008b. The boundaries of the West African craton, with The articles cover 12 countries, with the 59 authors coming from a special reference to the basement of the Moroccan metacratonic Anti- 12 countries including 22 authors from Africa. Atlas belt. In: Ennih, N., Liegeois, J.-P. (Eds.), The Boundaries of the West This special issue is a companion to three other special issues African Craton. Geological Society, London, Special Publications, 297, pp. 1e17. consisting of research on the West African Craton (Precambrian Harrell, J.A., Brown, V.M., 1992. The World's oldest surviving geological map: the Research, Economic Geology & Ore Geology Reviews), and 1150 B.C. Turin Papyrus from Egypt. J. Geol. 100, 3e18. together hopefully form the impetus for a renewed interest in Hein, K.A.A., Matsheka, I.R., Bruguier, O., Masurel, Q., Bosch, D., Delphine, Caby, R., the geology of this fascinating region that has been the subject Monie, P., 2015. The yatela gold Deposit: 2 Billion Years in the Making. http:// dx.doi.org/10.1016/j.jafrearsci.2015.07.017. of intense exploration by the minerals industry over the last 10 Hichem, B., Mohamed, H., Abderrahmane, B., Ivan, P., Karim, A., 2015. 3D struc- years. tural cartography based on magnetic and gravity data inversion e case of South-West Algeria. J. Afr. Earth Sci. http://dx.doi.org/10.1016/j.jafrear sci.2015.02.001. Hubert, H., 1934. Carte Geologique, Afrique Occidentale Française et Togo. Echelle 1, Acknowledgements 6M. Available for viewing at. http://yves.cordelle.free.fr/CDFamilialAvant Sept1939/Photos4/1934c-AlbertH-AOFgeologique.jpg. We wish to gratefully acknowledge AMIRA International and the Jessell, M.W., Begg, G.C., Miller, M.S., 2015a. The geophysical signatures of the west african craton. Precambrian Res. http://dx.doi.org/10.1016/j.precamres.2015. sponsors (Rio Tinto, Gryphon, IAMGold, Azumah Resources, Gold- 08.010 (in press). enStar, Resolute, Castle Peak, SEMAFO, First Quantum, Drake Re- Jessell, M.W., Boamah, K., Duodu, J.A., Ley-Cooper, Y., 2015b. Geophysical evidence sources, Newcrest, VALE, Goldfields, Volta, Votorantim, Kinross, for a major paleochannel within the obosum Group of the Volta Basin, Northern Region, Ghana. J. Afr. Earth Sci. (in press) http://dx.doi.org/10.1016/j.jafrearsci. Avocet, AngloGold Ashanti, Fonds National de la Recherche 2015.04.007. Luxembourg), as well as AusAid and the ARC Linkage Project Jessell, M.W., Santoul, J., Baratoux, L., Youbi, N., Ernst, R.E., Metelka, V., Miller, J., LP110100667, for their support of the WAXI 2 project (P934A). Perrouty, S., 2015c. An updated map of West African mafic dykes. J. Afr. Earth Sci. http://dx.doi.org/10.1016/j.jafrearsci.2015.01.007 (in press). We are also appreciative of the contribution of the various Geolog- Junner, N.R., 1934. Geological Map of the Gold Coast. Southern Sheet. Showing Po- ical Surveys/Department of Mines in West Africa as sponsors in sitions of Gold Mines and Prospects. In: Gold Coast Geological Survey, 1: kind of WAXI 2 (Bureau des Mines et de la Geologie du Burkina 500,000 scale. (Available for viewing at: http://www.bmarchives.org/items/ (BUMIGEB); Centre de Recherches Geologiques et Minieres e show/100203728. Lenz, O., 1882. Geologische Karte von West-Afrika, Petermanns Geographische Mit- Niger; Direction Generale des Mines et de la Geologie- Togo; Direc- teilungen, 1:12,500,000 scale. tion Nationale de la Geologie et des Mines e Mali; Direction Natio- Metelka, V., Baratoux, L., Jessell, M.W., Naba, S., 2015. Visible and Infrared Properties nale de la Geologie - Republique de Guinee; Direction de la of Weathered to Unaltered Rocks from Precambrian Granite-Greenstone Ter- e e rains of the West African Craton. http://dx.doi.org/10.1016/j.jafrearsci. Geologie Senegal; Geological Survey Department Ghana; Min- 2015.xx.xxx. istry of Land, Mines and Energy e Liberia; L'Office Mauritanien de Parra-Avila, L.A., Bourassa, Y., Miller, J., Perrouty, S., Fiorentini, M.L., McCuaig, T.C., Recherches Geologiques- Mauritania). Finally, we wish to recognize 2015. Age constraints of the Wassa and Benso mesothermal Gold deposits, Ashanti Belt, Ghana, West Africa. http://dx.doi.org/10.1016/j.jafrearsci. our WAXI 2 research colleagues from the various Institutions from 2015.05.017. around the world (the BRGM, the University of Lorraine, the Institut Perrouty, S., Jessell, M.W., Bourassa, Y., Miller, J.M., Apau, D., Siebenaller, L.,

Please cite this article in press as: Jessell, M.W., Liegeois, J.-P.100 years of research on the West African Craton, Journal of African Earth Sciences (2015), http://dx.doi.org/10.1016/j.jafrearsci.2015.10.008 Editorial / Journal of African Earth Sciences xxx (2015) 1e5 5

* Velasquez, G., Baratoux, L., Ailleres, L., Beziat, D., Salvi, S., 2015. The Wassa de- Mark W. Jessell posit: a poly-deformed orogenic gold system in southwest Ghana - Implications Centre for Exploration Targeting, The University of Western Australia, for regional exploration. http://dx.doi.org/10.1016/j.jafrearsci.2015. 03.003. Roussel, J., Lesquer, A., 1991. Geophysics and the Crustal Structure of West Africa. In: 35 Stirling Highway, Crawley, WA 6009, Australia Dallmeyer, R.D., Lecorche, J.P. (Eds.), The West African Orogens and Circum- Atlantic Correlatives, IGCP-project 233. Springer-Verlag, Berlin Heidelberg, Laboratoire GET, Universite Toulouse 3 Paul Sabatier, IRD, CNRS UMR pp. 9e28, 405p. 5563, Observatoire Midi-Pyrenees, 31400 Toulouse, France Tshibubudze, A., Hein, K.A.A., McCuaig, T.C., 2015. The relative and absolute chro- nology of strato-tectonic events in the Gorom-Gorom granitoid terrane and Jean-Paul Liegeois Oudalan-Gorouol belt, northeast Burkina Faso. http://dx.doi.org/10.1016/ Isotope Geology, Royal Museum for Central Africa, B-3080 Tervuren, j.jafrearsci.2015.04.008. UNESCO, 1963. A Review of the Natural Resources of the African Continent. NC.62/ Belgium XII.L/A. UNESCO, Paris, p. 437. € * Villeneuve, M., Gartner, A., Youbi, N., El Archi, A., Vernhet, E., Rjimati, E.C., Corresponding author. Linnemann, U., Bellon, H., Gerdes, A., Guillou, O., Corsini, M., Paquette, J.L., 2015. The southern and central parts of the “Souttouﬁde” belt, Northwest Af- E-mail address: [email protected] (M.W. Jessell). rica. Journal of African Earth Sciences. http://dx.doi.org/10.1016/j.jafrearsci.2015.04.016 (in press). Available online xxx Vincent, H., Delmare, F., 2015. Carte de Keni eba et du Terrain Environnant les Mines, Levee pendant l'expedition du Bambouk, Execut ee en Août 1858. Echelle 1, 10,000. http://africanmapimages.grainger.illinois.edu/afm0003156.jp2.