May 2011 LIP of the Month

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Large igneous provinces of the West African Craton: The record preserved in regional dyke swarms.

Nasrrddine Youbi 1, 2 & 3 , Richard Ernst4,5, Ulf Söderlund 6, Hervé Bertrand 7 , Miguel Doblas 8 , Hind El Hachimi 1, Djiky Kouyaté 1 , Abderrahmane Soulaimani 1, Ahmid Hafid 9, Moha Ikenne 10, and Khalid Rkha Chaham 1

1 Dept of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco, Email: youbi@ucam.ac.ma

2 Centre National pour la Recherche Scientifique et Technique, Angle avenues des FAR et Allal El Fassi, Madinat Al Irfane B.P. 8027 Nations Unies, 10102 Rabat, Morocco ;

3 Centro de Geologia, Universidade de Lisboa (CeGUL), Faculdade de Ciências, Deparmento de Geologia, Lisboa, Portugal;

4 Ernst Geosciences, 43 Margrave Ave Ottawa, Ontario K1T 3Y2 Canada.

5 Department of Earth Sciences, Carleton University, Ottawa, Canada K1S 5B6. Email: Richard.Ernst@ErnstGeosciences.com

6 Lithosphere and Biosphere Sciences, Dept. of Earth and Ecosystem Sciences, Division of Geology, Lund University, Sölvegatan 12, S-223 62 Lund, Sweden, Email: Ulf.Soderlund@geol.lu.se;

7 Laboratoire Sciences de la Terre, ENS de Lyon et UCBL, 46, Allée d'Italie, 69364 Lyon, France. E mail : herve.bertrand@ens-lyon.fr

8 Departamento de Geología, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain

9 Dept of Geology, Faculty of Sciences & Technics Guéliz, Cadi Ayyad University, P.O. Box 549, Abdelkarim El Khattabi Avenue, Guéliz, Marrakech, Morocco, Email: a.hafid@fstg-marrakech.ac.ma;

10 Dept of Geology, Faculty of Sciences, Ibnou Zohr University, P.O. Box 28/S, Agadir, Morocco, Email: ikenne@univ-ibnzohr.ac.ma

Introduction

Regional dyke swarms are considered to represent periods of repeated crustal extension wherein enormous amounts of mantle-derived magmas ascend through the crust. Their distribution, palaeomagnetism, petrology, geochemistry and emplacement ages are of intense geodynamic interest since they provide invaluable clues to our understanding of the nature of the sub-continental lithospheric mantle. There is also an increasing global recognition of their utility in delineating the existence and extent of Large Igneous Provinces (LIPs) and, especially, to use their exact emplacement ages and dyke directions to reconstruct formerly adjacent crustal blocks (e.g., Bleeker and Ernst, 2006; Ernst and Bleeker, 2010). Thus, the study of dyke rocks is extremely important in order to reveal the configuration of ancient supercontinents.

In this contribution we present a preliminary survey of mafic dyke swarms of the West African craton (WAC). The synthesis demonstrates the complexity in the dyke record, suggesting that geochronological, petrological, geochemical and paleomagnetic characteristics of many dyke sets remain to be established before WAC and its shield areas can be put into a global plate tectonic framework (e.g., Youbi et al., 2010).

Geological setting of the West African Craton.

The WAC, stable since 2 Ga, constitutes the basement of northwestern Africa (e.g., Ennih and Liégeois, 2008). The WAC is composed of three Archean and Paleoproterozoic shields: the Reguibat Shield, the Anti-Atlas and the Leo-Man shield, separated by two cratonic sedimentary basins. The basement of the WAC was built through several major orogenic cycles: the Paleoarchean–Leonian cycle (multiple episodes between 3.5 and 3.0 Ga) related to continental accretion and volcano-sedimentary activity whose chronology remains uncertain (e.g., Thiéblemont et al., 2004), the Liberian cycle (2.95–2.75 Ga; Key et al., 2008), the Eburnian–Birimian cycle (2.2–1.75 Ga; Schofield et al., 2006) and the Pan-African orogenic event (760–660 Ma; Thomas et al., 2002). One of the main characteristics of the WAC is that no Mesoproterozoic events or rocks are known, suggesting a quiescent period between 1.7 and 1.0 Ga (e.g., Ennih and Liégeois, 2008). The exposed parts of the craton outcrop in two main uplifts: the Reguibat Shield in the north (Mauritania, Morocco and Algeria) and the Leo-Man Shield in the south, and in smaller inliers of the Anti-Atlas belt.

Figure 1: General geology of the West African craton (Fabre, 2005; Liégeois et al., 2005; Ennih and Liégeois, 2008).

Petrogrphical and geochemical data on mafic dyke swarms in the WAC

The dykes and sills of the WAC display remarkably uniform textural, mineralogical and geochemical features throughout the area in which they occur. They all consist essentially of tholeiitic basalts and are typically composed of plagioclase + clinopyroxene (augite) ± orthopyroxene (enstatite) ± olivine displaying doleritic texture and variable grain size. From the geochemical point of view, they are all characterized by a clear negative Nb anomaly, indicating a plausible subduction fingerprint and/or crustal contamination (e.g., Bassot et al., 1986; Ikenne et al., 1997; Hafid et al., 2001; Verati et al., 2005 Deckart et al., 2005; Chabou et al., 2010; Cournède, 2010). The similarities of all their trace element patterns play in favor of a single geodynamic environment or a common influence of contamination from sub-lithospheric mantle. These conditions should have been consistent for a long period of time, according to the large range of available ages.


Figure 2: Primitive mantle-normalized trace element 'spidergrams' of selected dyke swarms from the West African craton (a) CAMP dyke swarms of Mali, Algeria, and Guinea (Deckart et al., 2005; Verati et al., 2005; Chabou et al., 2010). Symbols: open triangle, Intermediate-Ti group dykes of Taoudenni basin, Mali; filled triangle, Low-Ti group dykes of Taoudenni basin, Mali ; open square, Low-Ti group of dolerite of Reggane basin ; filled square, Low-Ti group of dolerite of Hank basin; open diamond, Low-Ti group of dolerite of Fersiga; filled diamond, Great Ksi-Ksou dyke; open circle, Fouta Djalon dolerite dykes, Guinea and (b) Precambrian dyke swarms of Burkina Faso (Cournède, 2010). Symbols: open triangle, Dolerite dykes trending NW-SE with an approximate age ranging from 2200 ± 370 Ma (Sm/Nd method) to 1631± 250 Ma (Rb/Sr method); filled triangle, Dolerites dykes trending NE-SW with an approximate age ranging from 847±360 Ma (Sm/Nd method) to 664±280 Ma (Rb/Sr method). Primitive mantle normalizing values are from Sun and McDonough (1989).

Geochronological data on mafic dyke swarms in the WAC

The compilation of geochronological data on mafic dyke swarms in the West African Craton is dominated by the identification of the so-called Central Atlantic Magmatic Province (CAMP), although it has become increasingly apparent that not all mafic dyke swarms fall into this category (Table 1).

The CAMP LIP was emplaced at ca. 200 Ma, close to the Triassic–Jurassic boundary (Marzoli et al., 1999), during the early stages of the break up of the supercontinent of Pangaea that led to the opening of the Central Atlantic Ocean. CAMP magmatism is nowadays represented by remnants of intrusive (crustal underplates, layered intrusions, sills, dykes) and extrusive (pyroclastic sequences and lava flows) rocks that occur in once-contiguous parts of northwestern Africa, southwestern Europe, and North and South America (e.g., McHone and Puffer, 2003; Youbi et al., 2003; Knight et al., 2004; Marzoli et al., 2004). It may have covered over 7 x 106 km2, with a total volume of magma estimated at 2–4×106 km3 and was active for no more than 4-5 Ma. 40Ar/39Ar plateau ages of CAMP range from 205 to 190 Ma, with a peak activity around 199 Ma on the African margin (e.g., Nomade et al., 2007). Preserved lava flows, common in Morocco and Portugal (e.g., Bertrand, 1991; Youbi et al., 2003; Martins et al., 2008), are rare in Algeria, North and South America, and have been dated between 203 and 190 Ma, again with peak activity at about 197-199 Ma (e.g., Chabou et al., 2007; Verati et al., 2007). Most of the CAMP rocks are tholeiitic low-Ti Continental Flood Basalts (CFBs), whereas high Ti CFBs are restricted to a narrow zone in the southern margin of the WAC (Liberia, Sierra Leone) and north-eastern South America (Surinam, French Guyana and northern Brazil) (e.g., Merle et al., 2011). However, the geographic boundaries of the CAMP remain uncertain, especially in Africa and South America. Recent investigation suggests that the CAMP was emplaced as far as the sub-Andean area in southern Bolivia, about 3000 km from the Atlantic margin (Bertrand et al., 2005) and indicates that the extension of the CAMP magmatism is probably much larger than previously recognized. The Central Atlantic LIP is considered as the result of a mantle super-plume (e.g., Oyarzun et al., 1997; Wilson, 1997) or, alternatively, as a consequence of lithosphere extension and thinning, pre-dating the Atlantic opening, that triggered decompressional melting in the upper asthenosphere (e.g., Withjack et al., 1998). Magmatism is apparently coeval with the mass extinction at the Triassic–Jurassic boundary (e.g., Van de Schootbrugge et al., 2009).

In addition to the mafic dyke and sill swarms that are linked to the CAMP LIP, a number of mafic units can be linked to the CIMP and the EUNWA LIP groups (each representing a clustering of related LIPs emplaced over a more extended time). The so-called Central Iapetus Magmatic Province (CIMP) was emplaced during Ediacaran-Cambrian times, and has been linked to the disruption of the supercontinent of Rodinia (Pannotia) leading to the initial opening of the Central Iapetus Ocean in the triple junction Laurentia, Baltica, and Amazonia or northwestern Africa (e.g., Ernst and Buchan, 1997; Puffer, 2002, Doblas et al., 2002, Coltice et al., 2007; Ernst and Bleeker; 2010; Ernst and Bell, 2010). As for the CAMP, the Central Iapetus LIP group has been variably considered as the result of a mantle super-plume (e.g., Puffer, 2002) or of heat incubation below the Rodinian (Pannotian) super-continent (e.g., Doblas et al., 2002; Coltice et al., 2007). Although major volcanic events are commonly associated with environmental hardship and even mass extinction (example CAMP versus Triassic-Jurassic mass extinction), the CIMP LIP group correlates with the beginning of a major expansion in the diversity and quantity of marine life during the early Cambrian: the Cambrian bio-radiation event (Puffer, 2002). It correlates also with the last Precambrian glaciation: the so called Gaskiers glaciation that occurred around 580 Ma. Major glaciations (e.g., Eyles, 2008), are associated to an extensional context and to LIPs. Volcanic activity may have enhanced the climate change (e.g., Stern et al., 2008). These authors develop and explore the hypothesis that explosive volcanism was at least partly responsible for Neoproterozoic climate change, synopsized as the “Volcanic Winter to Snowball Earth” (VW2SE) hypothesis. The CIMP magmatism is best studied along the Laurentian margin (Puffer 2002; Ernst and Buchan 2001, 2004; McCausland et al. 2007) and has main pulses at ca. 615 Ma, 590 Ma, 560 and 550 Ma, which are potentially linked with the progressive breakup of the eastern Laurentian margin (Kamo et al. 1989; Bingen et al. 1998; Waldron and van Staal 2001; Cawood et al. 2001; Ernst and Buchan 2004). It is also present in Baltica (e.g., Ernst and Bell, 2010 and references therein) where it is best expressed by the Ediacaran CFB from the southwestern margin of the East European Craton in Ukraine. Whole-rock 40Ar/39Ar age determination revealed plateau ages at 590–560 Ma (Elming et al., 2007). In Africa, the CIMP LIP group is well represented around the WAC (e.g., Doblas et al, 2002), in particular in the High and the Anti-Atlas of Morocco, where it occurs as dyke swarms (Ediacaran Assarag -Douar Eçour dyke Swarms) that represent the feeder dykes of the volcanic successions of the Ouarzazate Group (formerly “PIII” of Choubert, 1963). The Ouarzazate Group represents a volcano-sedimentary sequences highly variable in thickness consisting of coarse volcanic conglomerates, ignimbritic rhyolites, trachytes, andesites, basalts, tuffites, and rare interbedded stromatolitic layers and fault scarp breccias. Various types of intrusions, such as granitoid massifs, necks, dykes or ring dykes are emplaced within the early Ouarzazate Group and within underlying units. The Sidi El Houssein alkaline granite (579 ± 7 Ma) is a typical example of ring-complex intrusion within the Eburnian basement. Felsic volcanics from the Ouarzazate Group were dated in several inliers: between 575 and 560 Ma in the Sirwa Window which includes the Zenaga inlier (U–Pb SHRIMP on zircons, Thomas et al., 2002); 563 ± 5 Ma and 580 ± 12 Ma in the Central Anti-Atlas (U–Pb zircon; Mifdal and Peucat, 1985); 565 ± 7 Ma in the Tagragra de Tata inlier (U–Pb SHRIMP on zircons; Walsh et al., 2002); 550 ± 3 Ma in the Imiter inlier (U–Pb IMS 1270 on zircons; Cheilletz et al., 2002). The Ouarzazate Group has not recorded the Pan-African deformation, but was deposited on a highly variable basement topography, which, coupled with the large and rapid variations in thickness of the Ouarzazate Group itself, strongly suggests that this group was deposited during active tectonics, most probably associated with transtensional movements (Doblas et al., 2002; Gasquet et al., 2005, 2008).

The so-called European North West African Magmatic Province (EUNWA or EUNWAMP) (e.g., Doblas et al., 1998; see also Wilson et al., 2004) was emplaced during Carboniferous-Permian times, and has been linked to the gravitational collapse of the previously overthickened and weakened Hercynian (Variscan) orogenic belt (the initial stages of the disruption of the Pangaean supercontinent). The whole Variscan edifice collapsed through simple-pure shear low-angle extensional detachments during the late Variscan, giving rise to Basin and Range type extensional province in Europe, and northwestern Africa involving major low angle detachment faulting, unroofing of large metamorphic core complexes, and synextensional plutonic bodies, dyke and sill swarms and volcanic successions. Coevally with an extensional scenario, Europe, and northwestern Africa were affected by a complex system of conjugate strike slips faults (NE-SW sinistral and NE-SE dextral) which partially disrupted the Variscan edifice, resulting in new Permo-Carboniferous stress pattern with the principal compressional axis oriented N-S (Arthaud and Matte, 1975; 1977). This episode was accompanied by sediment deposition and volcanism in transtensional and pull-apart basins (Youbi et al., 1995; Doblas et al., 1998). This episode resulted from dextral transcurrent movement along an intracontinental zone located between Gondwana and Laurussia an early proposal of Van Hilten (1964) later reinterpreted by Arthaud and Matte (1975; 1977). To date a range of chronometers has been applied to determine eruption ages from across the region of the EUNWA LIP group including whole-rock Rb–Sr and K–Ar dating, 40Ar/39Ar dating of mineral separates and U–Pb dating of zircon, titanite and perovskite (e.g., Timmerman et al., 2009). The duration of activity is currently estimated to span a period of ca. 100 million years, from Early Carboniferous to Upper Permian-Early Triassic (350–250 Ma), with several hiatuses (Upton et al., 2004). Three main pulses can be distinguished at ca. 300 Ma, 290-275 Ma, and 250 Ma, and each of these pulses can be considered a separate LIP within the overall EUNWA LIP group. These eruptive cycles are well represented in Morocco in northwestern Africa and also in southern Scandinavia and northern Germany. The huge volume of extruded and intruded magmatic products of the EUNWA magmatic province (example in the Oslo Graben, the estimated volume is at ca. 35,000 km3 while in the North German Basin, the total volume of felsic volcanic rocks, mainly rhyolites and rhyodacites, was of the order of 48,000 km3) has led to suggestions of a thermally anomalous mantle plume to explain this pulse of the magmatism (Ernst and Buchan, 1997; Torsvik et al., 2008). A significant detractor from a plume hypothesis is the duration of activity and the helium isotope signature of lithospheric mantle xenoliths from the Scottish Permo-Carboniferous dykes, sills and vents (Kirstein et al., 2004). The EUNWA magmatic province may have contributed to the great Gondwanan glaciation that occurred from the Late Devonian to the Late Permian (Veevers and Powell, 1987; Crowell, 1999; Isbell et al., 2003). Glaciers achieved their maximum paleolatitudinal range between the middle Stephanian (ca. 305 Ma ago) and near the end of the Sakmarian (ca. 284 Ma ago) (Isbell et al., 2003). This hypothesis is termed the icehouse–silicic large igneous province (SLIP) hypothesis (Cather et al., 2009).

Country Location-Dyke/Sill complex or intrusions Age (Ma) Method Reference LIPs
Algeria Reguibat Shield Dyke Swarm 1900 ±  0.05 Pb-Pb (baddeleyite)  [1,2]   
Algeria Hoggar-Tin Serririne  Dyke Swarm 351.6 ±16.0-347.6 ± 16.2  K-Ar (whole-rock/plagioclase )  [3,4]  EUNWA ?
Algeria Ksi-Ksou Dyke 198.0 ± 1.8 Ar-Ar (plagioclase)  [5]  CAMP
Algeria Hank-Reggane- Fersiga  Sills & Dykes 197.9 ± 2.0 -195.0 ± 1.6  Ar-Ar (plagioclase)  [6]  CAMP
Algeria Reggane Sill 166 K-Ar (whole-rock )  [7]  CAMP
Algeria Hoggar-Tin Seririne 369 ± 9 K-Ar (whole-rock )  [8]  EUNWA ?
Burkina Faso Central Burkina Faso 250 ± 13    [9,10]  EUNWA ?
Burkina Faso Central Burkina Faso 1814  ±  26    [9]   
Burkina Faso Dolerites dykes trending NW-SE 2200 ± 370 Ma  Sm-Nd (whole-rock) [11]   
Burkina Faso Dolerites dykes trending NW-SE 1631± 250 Ma  Rb-Sr (whole-rock) [11]   
Burkina Faso Dolerites dykes trending NE-SW  847±360  Sm-Nd (whole-rock) [11]   
Burkina Faso Dolerites dykes trending NE-SW  664±280 Ma  Rb-Sr (whole-rock) [11]   
Guinea Kakoulima-Fouta Djalon  Dyke Swarm  200.4 ±  0.2- 194.8 ±  0.5  Ar-Ar (biotite) [12,13]  CAMP
Guinea Bafata-Burquelem Dyke Swarm 197 ± 7- 153 ±  3 Ma K-Ar (whole-rock )  [14]  CAMP
Liberia Liberia Dyke Swarm 197  ± 6-177  ± 4  K-Ar ( plagioclase, pyroxene, whole-rock )  [15]  CAMP
Liberia Liberia Dyke Swarm 186 ± 4 Ma - 201± 2 K-Ar (whole-rock )  [16]  CAMP
Liberia Liberia Dyke Swarm 196 ± 4 Ma - 177 ± 4 K-Ar (plagioclase, whole-rock)  [17,18]  CAMP
Liberia Liberia Dyke Swarm 185.0 ± 4.4- 187.0 ±  3.4 Ar-Ar (plagioclase)  [15]  CAMP
Mali Gourma 275 ± 14-260 ± 13 K-Ar (whole-rock )  [19]  EUNWA ?
Mali Banfora 250 ± 13 K-Ar (whole-rock )  [19]  EUNWA ?
Mali Taoudenni  Dyke Swarm 203.7 ± 2.7-200.9 ± 2.5 Ar-Ar (plagioclase)  [5]  CAMP
Mali Taoudenni  Dyke Swarm 200.0 ± 0.7 -197.6 ± 0.8  Ar-Ar (plagioclase)  [20]  CAMP
Mali Taoudenni Dyke Swarm 199.8  ±  2.6-196.6 ± 1.0 Ar-Ar (plagioclase)  [20]  CAMP
Mali Taoudenni Sills Drilling ONU 202.4  ±  1.6-198.9  ±  1.2 Ar-Ar (plagioclase)  [20]  CAMP
Mauritania Reguibat Shield Dyke Swarm 1757-815  K-Ar (whole-rock )  [21]   
Mauritania Reguibat Shield Dyke Swarm 1609 ± 45 Rb-Sr (whole-rock )  [22]   
Mauritania Taoudenni Adrar Sill 308.9 ± 1.1 - 233 ± 1 Ar-Ar (plagioclase)  [22] EUNWA ?
Mauritanie Ballé 230 ± 11 K-Ar (whole-rock )  [19] EUNWA ?
Mauritanie Taoudenni  265 ± 13 K-Ar (whole-rock )  [19] EUNWA ?
Mauritanie Hodh & Akjoujt Dyke Swarm 201-172 K-Ar (whole-rock )  [23] CAMP
Mauritanie Hank Dyke Swarm 206-147/1507-1429/307-223 K-Ar (whole-rock )  [23] CAMP
Mauritania Amsaga -Reguibat Shield Dyke Swarm 2706  ±  54 Ma Sm-Nd (plagioclase, pyroxene, whole-rock) [24]  
Morocco Anti-Atlas-Tagragra of Tata Dyke Swarm 2040 ±  6  SHRIMP U-Pb (zircon)  [25]  
Morocco Anti-Atlas-Zenaga  Dyke Swarm 2039.7  ±  2.1 U-Pb (zircon) [26,27]  
Morocco High-Atlas-Douar Eçour Dyke Swarm 579 ± 7 -  559 ± 6  SHRIMP U-Pb (zircon)  [28] CIMP
Morocco Anti-Atlas-Assarag  Dyke Swarm 579 ± 7 - 559 ± 6  SHRIMP U-Pb (zircon)  [28] CIMP
Morocco Anti-Atlas-Agnou Mghar Dyke 317 ± 7 - 236 ± 40 K-Ar (whole-rock )  [29] EUNWA ?
Morocco Anti-Atlas-Ighrem-Asdrem Dyke 210 ± 10 -174 ±  5 K-Ar (whole-rock )  [29] CAMP
Morocco Foum Zguid Dyke 187 ±  4 -182 ±  4 K-Ar (whole-rock )  [30] CAMP
Morocco Foum Zguid Dyke 168 ±  5 -152 ±  5 / 235 ± 10 K-Ar (whole-rock )  [31] CAMP
Morocco Foum Zguid Dyke 196.9 ± 1.8 Ar-Ar (plagioclase)  [5] CAMP
Morocco Draa Valley Sills 186 ±  3 -180 ±  4 K-Ar (whole-rock )  [30] CAMP
Nigeria Oban-Obudu Dyke Swarm 219.9 ±  4.7-204.0 ± 9.9  K-Ar ( plagioclase)  [32] CAMP
Nigeria Oban-Obudu Dyke Swarm 140.5 ±  0.7 Ar-Ar ( plagioclase)  [33] CAMP ?
Niger Bossé Bangou 1011 ± 45.7 K-Ar (whole-rock )  [34]  
Niger Libiri (Bolsi-Bossé Bangou) 1377.6 ± 35.5 K-Ar (whole-rock )  [34]  
Niger Bilabé 1379.5 ± 26.9 K-Ar (whole-rock )  [34]  
Niger Gabou (Tilabéri) 896 ± 24.5 K-Ar (whole-rock )  [34]  
Senegal Sambarabougou-Kondhoko Dyke Swarm 1339 ± 37- 1124 ±  24 K-Ar (whole-rock )  [14]  
Senegal Etiolo Dyke Swarm 463 ±  13 K-Ar (whole-rock )  [14]  
Senegal N'Débou Dyke Swarm 325 ± 17- 311 ±  14/170 ±  5 K-Ar (whole-rock )  [14] EUNWA ?
Sierra Leone Freetown Complex 194 ±  8-165 ± 10 K-Ar (whole-rock )  [35] CAMP
Sierra Leone Freetown Complex 196.3 ±  3 -232.1 ±  9 Ar-Ar (amphibole, biotite, plagioclase)  [36,37] CAMP

Notes for Table 1: Geochronological data on mafic dyke swarms in the West African Craton. [1] Aïfa et al., (2001); [2] Lefort and Aïfa (2001) ; [3] Djellit et al., (2006); [4] Derder et al., (2006); [5] Sebai et al. (1991); [6] Chabou et al. (2007); [7] Conrad et al., (1972); [8] Bayou et al., (2004); [9] Castaing et al. (2003); [10] Marcelin and Serre (1971); [11] Cournède (2010); [12] Deckart et al. (1997); [13] Nomade et al. (2007); [14] Bassot et al. (1986); [15] Dalrymple et al. (1975); [16] Mauche et al. (1989); [17] Lanphere and Dalrymple (1971); [18] Lanphere and Dalrymple (1976); [19] Lay and Reichelt 1971); [20] Verati et al. (2005); [21] Dosso et al. (1979); [22] Rooney et al. (2010); [23] Dosso (1975); [24] Potrel et al. (1998); [25] Walsh et al. (2002); [26] Kouyaté et al. (2010a); [27] Kouyaté et al. (2010b); [28] Thomas et al. (2002); [29] Huch,(1988); [30] Hailwood and Mitchell (1971); [31] Leblanc (1973); [32] Ekwueme et al. (1997); [33] Ekwueme (1994); [34] Ama Salah (1991);[35] Briden et al. (1971); [36] Barrie et al. (2006); [37] Barrie et al. 2010). CAMP = the Late Triassic-Early Jurassic Central Atlantic Magmatic Province; CIMP = the Late Neoproterozoic Central Iapetus Magmatic Province; EUNWA = the Permo- Carboniferous European North-West African Magmatic Province.

Economic potential of mafic dyke swarms in the WAC

Few minerals of economic importance are associated with minor basic intrusions, and the dykes and sills dolerites of the WAC are no exception to this rule. There is always the possibility of contact metasomatism or hydrothermal mineralization, but the titanium-rich magnetite and copper findings near Nioro in the southern Taoudenni basin (where dolerite intrudes limestone), are almost certainly of curiosity value only. Limited amounts of iron have formed by lateritic alteration of a thicker sill in Guinea. There are Ti-rich magnetite deposits in the Freetown Complex (of the CAMP event), and sulphides of copper as well as nickel associated with platinum and gold. However, the grades are very low and the total amount involved is probably rather low since the intrusion itself is of relatively small size. The main use of dolerites is as crushed rock for construction work and rail ballast.

Acknowledgements.

This work is a contribution to the following research projects: (i) International Collaborative Research Grant, Swedish-MENA Research Links Programme to Ulf Söderlund, and Nasrrddine Youbi, which is funded by the Swedish Research Council (SRC) and the Swedish International Development Cooperation Agency (SIDA); (ii) International Government-Industrial-Academic Programme “Reconstruction of Supercontinents Back To 2.7 Ga Using The Large Igneous Province (LIP) Record, With Implications For Mineral Deposit Targeting, Hydrocarbon Resource Exploration, and Earth System Evolution” (see the URL http://www.supercontinent.org/ for more details) and (iii) PICS, CNRS (France) - CNRST (Morocco) to Hervé Bertrand and Nasrrddine Youbi.

References

Aïfa, T., Lefort, J.P., & Drareni, A. (2001) New Paleopoles at 1.4 - 1.9 Ga from Dyke Swarms of the West African Craton: Paleomagnetic Contribution to the Accretionary Phase of Rodinia. Gondwana Research, v. 4, no. 4, pp. 559-560.

Ama Salah, I. (1991) Pétrographie et relations structurales des formations métavolcaniques et sédimentaires du Birimien du Niger occidental. Problème de l'accrétion crustale au Protérozoïque inférieur Thèse Doctorat Université. Université d'Orléans, Orléans, France.

Arthaud, F., & Matte, P. (1975). - Les décrochements tardi-hercyniens du Sud-Ouest de l'Europe. Géométrie et essai de reconstitution des conditions de la déformation. Tectonophysics, v. 25, pp. 139-171.

Arthaud F. & Matte P. (1977). - Late Paleozoic strike-slip faulting in southern Europe and northern Africa result of a right-lateral shear zone between the Appalachians and Urals. Geological Society of America Bulletin, v. 88, pp. 1305-1320.

Barrie, I. J. (2006). Tectono-thermal evolution of the Sierra Leone Passive Continental Margin, West Africa: Constraints from thermochronology. Goldschmidt Conference Abstracts 2006, Geochemica et Cosmochemica Acta 70 (18): A36- A36 Suppl. S Aug-Sep 2006. doi:10.1016/j.gca.2006.06.181.

Barrie, I. J., Wijbrans, J., Andriessen, P., Beunk, F., Strasser-King, V., & Fode, D. (2010). Combined 40Ar/39Ar and Fission-Track study of the Freetown Layered Igneous Complex, Freetown, Sierra Leone,West Africa: Implications for the Initial Break-up of Pangea to form the Central Atlantic Ocean and Insight into the Post-rift Evolution of the Sierra Leone Passive Margin. Geophysical Research Abstracts. Vol. 12, EGU2010-7322-2, 2010. EGU General Assembly 2010.

Bassot, J.P., Cantagrel, J.M., Jamond, C., & De Carvalho, H. (1986). Nouvelles données géochronologiques sur les dolérites et gabbros de l’est du Sénégal et de la Guinée Bissau. Réflexions sur l’âge de mise en pl      ace et la répartition du magmatisme « continental » à l’échelle de l’Afrique de l’Ouest. Garcia de Orta, Revista da Junta de Investigações do Ultramar, Série Geol, Lisboa, v. 9, no. 1-2, pp. 1-14.

Bayou, B. , Derder, M.E.M., Henry, B. , Djellit, H. , Amenna, M. , Khaldi, A. , Ouabadi, A., &  Baziz, K. (2004). Paléomagnétisme des roches sédimentaires et magmatiques du Dévonien du bassin de Tin Seririne (Bordure Sud du Hoggar, Algérie). 20ème Colloque de Géologie Africaine, 20th Colloquium of African Geology, Volume des Résumés, Abstracts Volume, BRGM, Orléans, p. 69.

Bertrand, H. (1991). The Mesozoic tholeiitic province of northwest Africa: a volcanotectonic record of the early opening of Central Atlantic. In: Kampunzu, A.B., Lubala, R.T. (eds.), Magmatism in Extensional Structural Settings. The Phanerozoic African Plate, Springer-Verlag, pp. 147–191.

Bertrand, H., Fornari, M., Marzoli, A., Sempere, T., Feraud, G. (2005).- Early Mesozoic rift-related magmatism in the Bolivian Andes and Subandes: the southernmost record of the Central Atlantic Magmatic Province. In: 6th International Symposium on Andean Geodynamics (ISAG 2005, Barcelona). Extended Abstracts: p. 111–114.

Bingen, B., Demaiffe, D. & van Breemen, O. (1998). - The 616 Ma old Egersund basaltic dike swarm, SW Norway, and Late Neoproterozoic opening of the Iapetus Ocean. Journal of Geology, v. 106, pp. 565–574.

Bleeker, W. & Ernst, R. (2006) Short-lived mantle generated magmatic events and their dyke swarms: The key unlocking Earth's paleogeographic record back to 2.6 Ga. In: Dyke Swarms-Time Markers of Crustal Evolution, edited by E. Hanski, S. Mertanen, T. Rämö & J. Vuollo, Taylor & Francis/Balkema, the Netherlands, pp. 3-26.

Bridena, C., Henthorna, D.I. & Rexa, D.C. (1971). Palaeomagnetic and radiometric evidence for the age of the Freetown igneous complex, Sierra Leone. Earth and Planetary Science Letters, v. 12, no.4, pp. 385-391.

Castaing, C., Billa, M., Milesi, J.P., Thiéblemont, D., Le Metour, J., Egal, E., Donzeau, M., Guerrot, C., Cocherie, C., Chevremont, P., Tegyey, M., Itard, Y., Zida, B., Ouedraogo, I, Kote, S., Kabore, B.E., Ki, J.-C. & Zunino, C. (2003). . Notice explicative de la carte géologique et minière au 1/1 000 000 du Burkina Faso. Edition du BRGM, 147 p. 

Cather,S.M., Dunbar, N.W., McDowell, F. W., McIntosh, W. C. & Scholle, P.A. (2009). - Climate forcing by iron fertilization from repeated ignimbrite eruptions: The icehouse–silicic large igneous province (SLIP) hypothesis. Geosphere, v. 5, no. 3, pp. 315-324.

Cawood, P.A., McCausland, P.J.A., & Dunning, G.R. (2001) Opening Iapetus: constraints from the Laurentian margin in Newfoundland. Geological Society of America Bulletin, v. 113, pp. 443–453.

Chabou M.C., Sebai, A., Féraud, G., & Bertrand, H. (2007) Datation 40Ar/39Ar de la province magmatique de l’Atlantique central dans le Sud-Ouest algérien. Comptes Rendus Geoscience, v. 339, pp.970-978.

Chabou M.C., Bertrand, H., & Sebai, A. (2010). Geochemistry of the Central Atlantic Magmatic Province (CAMP) in south-western Algeria. Journal of African Earth Sciences, v. 58, no. 2, pp. 211-219.

Cheilletz, A., Levresse, G., Gasquet, D., Azizi Samir, M.R., Zyadi, R., & Archibald, D.A. (2002). The Imiter epithermal deposit (Morocco): new petrographic, microtectonic and geochronological data. Importance of the Precambrian–Cambrian transition for major precious metals deposits in the Anti-Atlas. Miner. Deposita, v.  37, pp. 772–781.

Choubert G. (1963). Histoire géologique du Précambrien de l'Anti-Atlas. Notes et Mém. Serv. géol. Maroc, Tome 1, n° 162. pp. 352. Rabat

Coltice, N., Phillips, B.R., Bertrand, H., Ricard, Y., & Rey, P. (2007) - Global warming of the mantle at the origin of flood basalts over supercontinents, Geology, v. 35, pp. 391-394.

Crowell, J.C., (1999). - Pre-Mesozoic ice ages; their bearing on understanding the climate system. Geological Society of America Memoir, 192, 106 p.

Conrad, J. (1972) Distension jurassique et tectonique éocrétacée sur le Nord-Ouest de la plate-forme africaine (bassin de Reggane, Sahara central), Comptes Rendus de l’Académie des Sciences de Paris, v. 274, pp. 2423–2426.

Cournède, C. (2010). Etude pétrographique, géochimique et paléomagnétique de dykes doléritiques au Burkina Faso, MSc. Thesis, Univ. Toulouse. 32 p.

Dalrymple, G.B., Gromme, C.S., & White, R.W. (1975). Potassium-argon age and paleomagnetism of diabase dikes in Liberia: initiation of central Atlantic rifting. Geological Society of America Bulletin, v. 86, pp. 399-411.

Deckart, K., Bertrand, H. & Liégeois, J.P. (2005) – Geochemistry and Sr, Nd, Pb  isotopic composition of the Central Atlantic Magmatic Province (CAMP) in Guyana and Guinea. Lithos, v. 81, pp. 289–314.

Deckart, K., Féraud, G. & Bertrand, H. (1997) Age of Jurassic continental tholeiites of French Guyana, Surinam and Guinea: implications for the initial opening of the Central Atlantic Ocean. Earth and Planetary Science Letters, v. 150, pp. 205–220.

Derder, M.E.M., Henry, B., Bayou, B., Ouabadi, A., Bellon, H., Djellit, H., Khaldi, A., Amenna, M., Baziz, K., Hemmi, A., & Guemache, M.A. (2006). New African Lower Carboniferous paleomagnetic pole from intrusive rocks of the Tin Serririne basin (Southern border of the Hoggar, Algeria). Tectonophysics, v. 418, pp. 189-203

Djellit, H., Bellon, H., Ouabadi, A., Derder M.E.M, Henry, B., Bayou, B., Khaldi, A., Baziz, K., & Merahi M.K. (2006). Âge 40K/40Ar, Carbonifère inférieur, du magmatisme basique filonien du synclinal paléozoïque de Tin Serririne, Sud-Est du Hoggar (Algérie). Comptes Rendus Geoscience, v. 338, pp. 624–631.

Doblas, M., Lopez-Ruiz, J., Cebria, J.M., Youbi, N., & Degroote, E. (2002). Mantle insulation beneath the west African craton during the Precambrian-Cambrian transition, Geology, v. 30, pp. 839-842.

Dosso L. (1975) La méthode potassium-argon. Datation de quelques dolérites de Mauritanie. Mémoire du Diplôme d’Ingénieur Géophysicien. 40p. 

Dosso, L., Vidal, Ph., Sichler, B., & Bonifay, A. (1979). Age précambrien de dolérites de la dorsale réguibat (Mauritanie). Comptes Rendus de l’Académie des sciences de Paris, 288, pp. 739-742

Ekwueme B.N. (1994) Basaltic magmatism related to the early stages of rifting along the Benue Trough: The Obudu dolerites of south-east Nigeria. Geological Journal, v. 29, no. 3, pp. 269–276.

Ekwueme, B. N., Itaya, T., & Yabe, H. (1997). K-Ar ages of intrusive rocks in the Oban-Obudu massif and their significance for the tectonic and plutonic history of southeastern Nigeria. Island Arc, v. 6, no. 4, pp. 353–360.

Elming, S.Å. Kravchenko, S.N. Layer, P. Rusakov, O.M. Glevasskaya, A.M. Mikhailova, N.P. & Bachtadse, V. (2007). Palaeomagnetism and 40Ar/39Ar age determinations of the Ediacaran traps from the southwestern margin of the East European Craton, Ukraine: relevance to the Rodinia break-up. Journal of the Geological Society, London, v. 164, pp. 969–982.

Ennih, N & Liégeois, J.P. (2008). The boundaries of the West African craton, with a special reference to the basement of the Moroccan metacratonic Anti-Atlas belt. In: Ennih, N. & Liégeois, J.-P. (eds), The Boundaries of the West African Craton. Geological Society, London, Special Publications, 297, pp. 1–17.

Ernst, R.E., & Buchan, K.L. (1997). Giant radiating dyke swarms: their use in identifying pre-Mesozoic large igneous provinces and mantle plumes. In: Mahoney J., & Coffin M. (Eds.) Large Igneous Provinces: Continental, Oceanic, and Planetary Volcanism, AGU Geophysical Monograph Series 100, pp. 297-333.

Ernst, R.E., & Buchan, K.L. (2001). The use of mafic dike swarms in identifying and locating mantle plumes. In: Ernst, R.E., & Buchan, K.L. (eds) Mantle plumes: their identification through time. Geological Society of America Special Paper 352, pp 247–265.

Ernst, R.E., & Buchan, K.L. (2004). Large igneous provinces (LIPs) in Canada and adjacent regions: 3 Ga to present. Geoscience Canada, v. 31, pp. 103–12.

Ernst, R.E., & Bell, K. (2010). Large igneous provinces (LIPs) and carbonatites. Mineralogy and Petrology, v. 98, pp. 55-76, doi: 10.1007/s00710-009-0074-1.

Ernst, R.E., & Bleeker, W. (2010). Large igneous provinces (LIPs), giant dyke swarms, and mantle plumes: significance for breakup events within Canada and adjacent regions from 2.5 Ga to present Canadian Journal of Earth Sciences, v. 47, pp. 695-739, doi: 10.1139/E10-025.

Eyles, N. (2008). - Glacio-epochs and the supercontinent cycle after 3.0 Ga: Tectonic boundary conditions for glaciation: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 258, pp. 89-129.

Fabre, J. (2005). - Géologie du Sahara occidental et central. Série/Reeks: Tervuren African Geosciences Collection, MRAC Tervuren, Belgique, 572 p.

Gasquet, D., Levresse, G., Cheilletz, A., Azizi-Samir, M.R., & Mouttaqi, A. (2005). Contribution to a geodynamic reconstruction of the Anti-Atlas (Morocco) during Pan-African times with the emphasis on inversion tectonics and metallogenic activity at the Precambrian-Cambrian transition, Precambrian Research, v. 140, pp. 157–182.

Gasquet, D., Ennih, N., Liégeois, J.P., Soulaimani, A.,& Michard, A. (2008). The Pan-African belt. In Michard A., Saddiqi, O., Chalouan A., & Frizon de Lamotte D., Continental Evolution: The Geology of Morocco. Lecture Notes in Earth Sciences, v. 33, pp. 33–64.

Hafid, A., Sagon, J.P., Julivert, M., Arboleya, M.L., Saquaque, A., El Boukhari, A., Saidi, A. & Soler, J.M.F. (2001). Neoproterozoic basic dykes of the Zenaga Inlier, central Anti-Atlas, Morocco: petrology, geochemistry and geodynamic significance. Journal of African Earth Sciences, v. 32: pp. 707-721.

Hailwood, E.A. & Mitchell, J.C. (1971) Paleomagnetic and radiometric dating results from Jurassic intrusions in south Morocco. Geophysical Journal of the Royal Astronomical Society, v. 24, pp. 351–364.

Huch, K. M. (1988) Die Panafrikanische Khzama-Geosuture in Zentralen Anti-Atlas Morokko. Petrographie Geochemie und geochronologie des subduktions-Komplexes der Tourtit-ophiolithe und der Tachankacht-gneise Sowie einiger Kollisionsgesteine om Nordosten des Sirwa-Kristallindoms, PhD Dissertation, Freie Univesität Berlin, 122 p., Berlin, Germany.

Ikenne M., Mortaji, A. Stussi, J.M. & Gasquet, D. (1997). Les filons basiques des boutonnières du Bas Draa et de la Tagragra d’Akka : témoins des distensions néoproterozoïques de l’Anti-Atlas occidental (Maroc). Journal of African Earth Sciences, v. 25, no. 2, pp. 209-223.

Isbell, J.L., Miller, M.F., Wolfe, K.L., & Lenaker, P.A. (2003). Timing of late Paleozoic glaciation in Gondwana; was glaciation responsible for the development of Northern Hemisphere cyclothems? In Chan, M.A., & Archer, A.W., (eds.), Extreme depositional environments; Mega end members in geologic time: Geological Society of America Special Paper 370, p. 5–24.

Kamo, S.L., Gower, C.F., & Krogh, T.E. (1989). Birthdate for the Iapetus Ocean? A precise U-Pb zircon and baddeleyite age for the Long Range dikes, southeast Labrador. Geology, v. 17, pp. 602–605.

Key, R.M., Loughlin, S.C., Gillespie, M., DelRio, M., Horstwood, M.S.A., Crowley, Q.G., Darbyshire, D.P.F., Pitfield, P.E.J., & Henney, P.J. (2008). Two Mesoarchaean terranes in the Reguibat shield of NW Mauritania. Geological Society, London, Special Publications 297(1), pp. 33–52.

Kirstein, L.A., Dunai, T.D., Davies, G.R., Upton, B.G.J., & Nikogosian, I.K. (2004). Helium isotope signature of lithospheric mantle xenoliths from the Permo-Carboniferous magmatic province in Scotland — no evidence for a lower-mantle plume. In: Wilson, M., Neumann, E.-R., Davies, G.R., Timmerman, M.J., Heeremans, M., & Larsen, B.T. (eds.), Permo-Carboniferous Rifting and Magmatism in Europe. Geological Society of London, Special Publications, v. 223, pp. 243–258.

Knight, K. B., Nomade, S., Renne, P. R., Marzoli, A., Betrand, H. & Youbi, N. (2004). The Central Atlantic magmatic province at the Triassic–Jurassic boundary: paleomagnetic and 40Ar/30Ar evidence from Morocco for brief, episodic volcanism. Earth and Planetary Science Letters, v. 228, pp. 143-160.

Kouyaté, D., Söderlund, U., Youbi, N., Ernst, R., Hafid, A., Ikenne, M, Soulaimani, A. & Rkha Chaham, K. (2010). Evidence of a 2040 Ma bimodal magmatic pulse associated with Paleoproterozoic rifting on the north-northwestern margin of the West African Craton. Unpublished Report #B2 (2 August 2010). Consortium Project for Reconstruction of Supercontinents Back To 2.7 Ga Using The Large Igneous Province (LIP) Record (www.supercontinent.org), Ernst Geosciences, 15 p.

Kouyaté, D., Söderlund, U., Youbi, N., Ernst, R., Hafid, A.. Ikenne, M, Soulaimani, A. & Rkha Chaham, K. (2010). U-Pb Geochronology of Dike Swarms of the Ifzwane suite dolerites of the Zenaga inlier (Anti-Atlas, Morocco): evidence of a 2040 ma bimodal magmatic pulse associated with palaeoproterozoic rifting on the northern margin of the West African Craton. Proceeding du 1er Congrès sur la Géologie du Maghreb, Tlemcen 10-12 novembre 2010. pp. 174-177.

Lanphere, M.A. & Dalrymple, G. B. (1971). A test of the40Ar/39Ar age spectrum technique on some terrestrial materials. Earth Planetary Sciences Letters, v. 12, pp. 359-372.

Lanphere, M.A. & Dalrymple, G. B. (1976). Identification of excess 40Ar by the 40Ar/39Ar age spectrum technique. Earth and Planetary Science Letters, v. 32, no. 2, pp. 141-148.

Lay, C. & Reichelt, R. (1971). Sur l’âge et la signification des intrusions de dolerites tholeitiques dans le bassin de Taoudenni (Afrique Occidentale). Comptes Rendus de l’ Académie des Sciences de Paris, v. 272, pp. 374- 376.

Leblanc, M. (1973). Le Grand Dyke de dolérites de l’Anti Atlas et le magmatisme jurassique du Sud-Marocain. Comptes Rendus de l'Académie des sciences de Paris, v. 276, D, pp. 2943-2946.

Lefort , J.P. & Aïfa, T. (2001). Paleomagnetic and Geochronological Evidence for a Large Rotation of the West African Craton Between 1.9 and 1.4 Ga: A Kinematic Model for the Fragmentation of Columbia and the Accretion of Rodinia. Gondwana Research, v. 4, no. 4, pp. 678-679.

Liégeois J.P., Benhallou A., Azzouni-Sekkal A., Yahiaoui R., & Bonin B., (2005). The Hoggar swell and volcanism: Reactivation of the Precambrian Tuareg shield during Alpine convergence and West African Cenozoic volcanism. In: Foulger, G.R., Natland, J.H., Presnall, D.C., & Anderson, D.L., eds, Plates, Plumes and Paradigms. Geol. Soc. Am. Spec. Pap. 388, pp. 379–400.

Marcelin, J. & Serre, J. C. (1971). Notice explicative de la carte géologique au 1/200 000. Feuille de Banfora-Sindou-Mangodara. Edition du BRGM, 34 p.

Martins, L. T., Madeira, J., Youbi, N., Munhá, J., Mata, J. & Kerrich, R. (2008). Rift-related magmatism of the Central Atlantic Magmatic Province in Algarve, Southern Portugal. In: Dostal, J., Greenough, J. D. & Kontak, D. J. eds.: Rift-related Magmatism, Lithos, v. 101, no. 1-2, pp. 102-124.

Marzoli, A., Bertrand, H., Knight, K., Cirilli, S., Buratti, N., Vérati, C., Nomade, S., Renne, P. R., Youbi, N., Martini, R., Allenbach, K., Neuwerth, R., Rapaille, C., Zaninetti, L. & Bellieni, G. (2004). Synchrony of the Central Atlantic Magmatic province and the Triassic–Jurassic boundary climatic and biotic crisis. Geology, v. 32, pp. 973–976.

Marzoli, A., Renne, P. R., Piccirillo, E. M., Ernesto, M., Bellieni, G., & De Min, A., (1999). Extensive 200 million-year-old continental flood basalts of the Central Atlantic Magmatic Province. Science, v. 284, pp. 616–618.

Mauche, R., Faure, G., Jones, L. M., & Hoefs, J. (1989). Anomalous isotopic compositions of Sr, Ar and O in the Mesozoic diabase dikes of Liberia, West Africa. Contributions to Mineralogy and Petrology, v. 10, pp. 12-18.

McCausland, P.J.A., Van der Voo, R. & Hall, C.M. (2007). Circum-Iapetus paleogeography of the Precambrian-Cambrian transition with a new paleomagnetic constraint from Laurentia. Precambrian Research, v. 156, pp. 125–152.

McHone, J. G. & Puffer, J. H. (2003). Flood basalt province of the Pangean Atlantic rift: regional extent and environmental significance. In: LeTourneau, P.M. & Olsen, P.E. (eds), The great rift valleys of Pangea in Eastern North America, Aspects of Triassic-Jurassic Rift Basin Geoscience, Volume 1. Columbia University Press, pp. 141-154.

Merle, R., Marzoli, A., Bertrand, H., Reisberg, L., Verati, C., Zimmermann, C., Chiaradia, M., Bellieni, G., & M. Ernesto. (2011). 40Ar/39Ar ages and Sr–Nd–Pb–Os geochemistry of CAMP tholeiites from Western Maranhão basin (NE Brazil). Lithos, v. 122, pp. 137-151.

Mifdal, A., & Peucat, J.J., (1985). Datations U/Pb et Rb/Sr du volcanisme acide de l’Anti-Atlas marocain et du socle sous-jacent dans la région de Ouarzazate. Apport au problème de la limite Précambrien–Cambrien. Sci. Géol. Bull., v. 38, pp. 185–200.

Nomade, S., Knight, K.B., Beutel, E., Renne, P.R., Vérati, C., Féraud, G., Marzoli, A., Youbi, N., & Bertrand, H. (2007). Chronology of the Central Atlantic Magmatic Province: implications for the Central Atlantic rifting processes and the Triassic–Jurassic biotic crisis, Palaeogeography., Palaeoclimatology, Palaeoecology, v. 244, no. 1–4, pp. 326–344.

Oyarzun, R., Doblas, M., López-Ruiz, J. & Cebriá, J. M. (1997). Opening of the central Atlantic and asymetric mantle upwelling phenomena: Implications for long-lived magmatism in western North Africa and Europe. Geology, v. 25, pp. 727-730.

Potrel, A., Peucat, J.J., & Fanning, C.M. (1998). Archean crustal evolution of the West African Craton: example of the Amsaga Area (Reguibat Rise). U–Pb and Sm–Nd evidence for crustal growth and recycling. Precambrian Research, v. 90, pp. 107–117.

Puffer, J.H. (2002). A late Neoproterozoic Eastern Laurentian superplume: location, size, chemical composition, and environmental impact. American Journal of Science, v. 302, pp. 1-27.

Rooney, A. D., Selby, D., Houzay, J.-P., & Renne, P. R. (2010). Re–Os geochronology of a Mesoproterozoic sedimentary succession, Taoudeni basin, Mauritania: Implications for basin-wide correlations and Re–Os organic-rich sediments systematic. Earth and Planetary Science Letters, v. 289, no. 3-4, pp. 486-496.

Sebai, A., Féraud, G., Bertrand, H. & Hanes, J. (1991). 40Ar/39Ar dating and geochemistry of tholeiitic magmatism related to the early opening of the Central Atlantic rift, Earth and Planetary Science Letters, v. 104, pp. 455-472.

Stern, RJ., Avigad, D., Miller, N., & Beyth, M. (2008). From Volcanic Winter to Snowball Earth:  Alternative explanation for Neoproterozoic Biosphere Stress. Springer Solid Earth Series “Links between Geological Processes, Microbial Activities, and Evolution of Life”. Y. Dilek, H. Furnes, K.Muehlenbachs Eds., pp. 313-337.

Sun, S-s. & McDonough, W. F. (1989). Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders, A.D.,  & Norry, M.J. (eds.) Magmatism in the Ocean Basins. Geological Society, London, Special Publications, No. 42, pp. 313-345.

Timmerman, M.J. Heeremans , M., Kirstein , L.A., Larsen , B.T. Spencer-Dunworth, E. A. & Sundvoll, B. (2009). Linking changes in tectonic style with magmatism in northern Europe during the late Carboniferous to latest Permian. Tectonophysics, v. 473, pp. 375–390.

Thomas, R.J., Chevallier,L.P., Gresse,P.G., Harmer,R.E., Eglington, B.M., Armstrong, R.A., deBeer, C.H., Martini, J.E.J., deKock, G.S., Macey, P.H., & Ingram, B.A. (2002). Precambrian evolution of the Sirwa Window, Anti-Atlas Orogen, Morocco. Precambrian Research, v. 118, no. 1–2, pp. 1–57.

Torsvik, T.H., Smethurst, M.A., Burke, K., & Steinberger, B., (2008). Long term stability in deep mantle structure: evidence from the ~300 Ma Skagerrak-Centered Large Igneous Province (the SCLIP). Earth and Planetary Science Letters, v. 267, pp. 444–452.

Upton, B.G.J., Stephenson, D., Smedley, P.M.,Wallis, S.M., & Fitton, J.G. (2004). Carboniferous and Permian magmatism in Scotland. In: Wilson, M., Neumann, E.-R., Davies, G.R., Timmerman, M.J., Heeremans, M., & Larsen, B.T. (Eds.), Permo-Carboniferous Magmatism and Rifting in Europe. Geological Society of London, Special Publications, v. 223, pp. 219–242.

Van de Schootbrugge, B., Quan, T. M., LIndström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschick, R., Röhling, H. G., Richoz, S., Rosenthal, Y. & Falkowski, P. G. (2009). Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience, v. 2, pp. 589-594.

Van Hilten, D. (1964). Evaluation of some geotectonic hypotheses by paleomagnetism. Tectonophysics, v. 1, pp. 3-5

Veevers, J.J., & Powell, M., (1987). Late Paleozoic glacial episodes in Gondwanaland reflected in transgressive depositional sequences in Euramerica: Geological Society of America Bulletin, v. 98, pp. 475–487.

Verati, C., Bertrand, H., & Féraud, G. (2005). The farthest record of the Central Atlantic Magmatic Province into West Africa craton: precise 40Ar/39Ar dating and geochemistry of Taoudenni basin intrusives (northern Mali), Earth Planetary Science Letters, v. 235, pp. 391-407.

Vérati, C., Rapaille, C., Féraud, G., Marzoli, A., Bertrand, H. & Youbi, N. (2007). 40Ar/39Ar ages and duration of the Central Atlantic Magmatic Province volcanism in Morocco and Portugal and its relation to the Triassic-Jurassic boundary. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 244, pp. 308–325.

Waldron,JWF & van Staal, CR (2001). Taconic orogeny and the accretion of the Dashwoods block: a peri-Laurentian microcontinent in the Iapetus Ocean. Geology, v. 29, pp.811–814.

Walsh, G.J., Aleinikoff, J., Benziane, F., Yazidi, A., & Amstrong, T.R. (2002). U–Pb zircon geochronology of the Palaeoproterozoic Tagragra de Tata inlier and its Neoproterozoic cover, western Anti-Atlas, Morocco. Precambrian Research, v.117, pp. 1–20.

Wilson, M. (1997). Thermal evolution of the Central Atlantic passive margins: continental break-up above a Mesozoic super-plume. Journal of the Geological Society, London, v. 154, pp. 491–495.

Wilson, M., Neumann, E.-R., Davies, G.R., Timmerman, M.J., Heeremans, M., & Larsen, N.T. (2004). Permo-carboniferous magmatism and rifting in Europe: introduction. In: Wilson, M., Neumann, E.-R., Davies, G.R., Timmerman, M.J., Heeremans, M., & Larsen, B.T. (Eds.), Permo-Carboniferous Magmatism and Rifting in Europe. Geological Society of London, Special Publications, v. 223, pp. 1–10.

Withjack, M. O., Schlische, R. W. & Olsen, P. E. (1998). Diachronous rifting, drifting, and inversion on the passive margin of central eastern north america: an analog for other passive margins. Association of the American Petroleum Geologists Bulletin, v. 82, no. 5A, pp. 817-835.

Youbi, N., Cabanis, B., Chalot-Prat, F. & Cailleux, Y. (1995). Histoire volcano-tectonique du massif permian de Khenifra (Sud-Est du Maroc Central). Geodynamica Acta., v. 8, no. 3, pp.158-172.

Youbi, N., Martins, L. T., Munhá, J. M., Ibouh, H., Madeira, J., Aït Chayeb, H. & El Boukhari, A. (2003). The Late Triassic-Early Jurassic Volcanism of Morocco and Portugal in the Framework of the Central Atlantic Magmatic province: An Overview. In: Hames, W. E., McHone, J.G., Renne, P. R. & Ruppel, C. (eds.): The Central Atlantic Magmatic Province: Insights from Fragments of Pangea. AGU Geophysical Monograph Series, v. 136, pp. 179-207.

Youbi, N. Söderlund, U., Ernst R., Bertrand, H. & Kouyaté D. (2010). Mafic Dyke Swarms in the West African Craton. Proceeding du Premier Congrès sur la Géologie du Maghreb, Tlemcen, Algeria, pp. 262-264.