全部 标题 作者
关键词 摘要

OALib Journal期刊
ISSN: 2333-9721
费用:99美元

查看量下载量

相关文章

更多...

Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

DOI: 10.1155/2012/938927

Full-Text   Cite this paper   Add to My Lib

Abstract:

This faulting tectonics analysis concerns the southernmost segment of the Dahomeyide Orogen and the West-African craton eastern margin in southeast Ghana. The analysis of strike-slip faults in the frontal units of the Dahomeyide Belt indicates that four distinct compressive events (NE-SW, ENE-WSW to E-W, ESE-WNW to SE-NW and SE-NW to SSE-NNW) originated the juxtaposition of the Pan-African Mobile Zone and the West-African craton. These paleostress systems define a clockwise rotation of the compressional axis during the structuring of the Dahomeyide Orogen (650–550 Ma). The SE-NW and SSE-NNW to N-S compressional axes in the cratonic domain and its cover (Volta Basin) suggest that the reactivation of the eastern edge of the West African craton is coeval with the last stages of the Pan-African tectogenesis in southeast Ghana. An extensional episode expressed as late normal faulting is also recorded in this study. This E-W to SE-NW extension, which is particular to the southernmost part of the Dahomeyide Belt, appears to be post-Pan-African. This extension probably contributed to the formation of a major Jurassic rifting zone that originated the Central Atlantic and the Benue Trough. 1. Introduction Southeast Ghana is a geologically complex area (Figure 1). It includes three distinct structural domains [1–5] (1) the southeastern margin of the West african craton (WAC) consisting of Archean to Paleoproterozoic assemblages that underwent the Eburnean Orogeny ( 2 0 0 0 ± 2 0 0 ?Ma); (2) the Neoproterozoic Volta Basin represented by its lower and middle megasequences (Bombouaka and Oti Supergroups); (3) the frontal structural units of the Pan-African Dahomeyide Orogenic Belt ( 6 0 0 ± 5 0 ?Ma). Figure 1: Schematic geological map with the “Stable Zone” (comprising the southeastern margin of the West african craton and its cover represented by the Volta Basin) and the Pan-African “Mobile Zone” (i.e., the frontal structural units of the Pan-African Dahomeyide belt): 1 = Eburnean basement complex (WAC); 2 = Neoproterozoic to Paleozoic cover (Volta Basin); 3 = internal and external gneiss-migmatite units; 4 = kyanite bearing micaceous quartzites; 5 = basic and ultrabasic massifs of the suture zone; 6 = Atacora or Akwapim structural unit; 7 = Buem structural unit; 8 = Meso-Cenozoic cover of the Gulf of Guinea Basin; 9 = thrust contact; 10 = Kandi fault mylonitic zone; A-B = schematic section line (Figure 2). The sedimentary sequence in the Volta Basin rests unconformably on the Eburnean basement complex. This basement and its cover constitute the western “Stable

References

[1]  P. Affaton, M. A. Rahaman, R. Trompette, and J. Sougy, “The dahomeyides orogen: tectonothermal evolution and relationships with the Volta basin,” in The West-African Orogen and Circum Atlantic Correlatives, Dallmayer and Lécorché, Eds., pp. 107–122, 1CGP, IUGS, UNESCO.
[2]  G. Rocci, G. Bronner, and M. Deschamps, “Crystalline basement of the West African craton,” in The West-African Orogen and Circum Atlantic Correlatives, Dallmayer and Lécorché, Eds., pp. 31–61, 1CGP, IUGS, UNESCO, 1991.
[3]  R. Trompette, “Neoproterozoic (600 Ma) aggregation of Western Gondwana: a tentative scenario,” Precambrian Research, vol. 82, no. 1-2, pp. 101–112, 1997.
[4]  F. Kalsbeek, D. Frei, and P. Affaton, “Constraints on provenance, stratigraphic correlation and structural context of the Volta basin, Ghana, from detrital zircon geochronology: an Amazonian connection?” Sedimentary Geology, vol. 212, no. 1–4, pp. 86–95, 2008.
[5]  J. N. Carney, C. J. Jordan, C. W. Thomas, D. J. Condon, S. J. Kemp, and J. A. Duodo, “Lithostratigraphy, sedimentation and evolution of the Volta Basin in Ghana,” Precambrian Research, vol. 183, no. 4, pp. 701–724, 2010.
[6]  P. Affaton, “Etude géologique et structurale du Nord-Ouest-Dahomey, du Nord-Togo et du Sud-Est de la Haute-Volta. Thèse de 3e Cycle,” Trav. lab. Sci. Terre St Jér?me, Marseille. Fr., Sér. B., 10, 217p, 1975.
[7]  P. Affaton, “Le basin des Volta (Afrique de 1'Ouest): une marge passive d'age Protérozo?que supérieur, tectonisée au Panafricain (600 ± 50 Ma),” Editions ORSTOM, Collection Etudes et Theses, Paris, 500p, 1990.
[8]  N. Simpara, Etude géologique et structurale des unités externes de la cha?ne panafricaine (600 Ma) des Dahomeyides dans la région de Bassar (Togo) [Ph.D. thesis], University of Aix-Marseille III, 1978.
[9]  P. Affaton, J. Sougy, and R. Trompette, “The tectono-stratigraphic relationships between the upper precambrian and lower paleozoic volta basin and the pan-african dahomeyide orogenic belt (West Africa),” American Journal of Science, vol. 280, no. 3, pp. 224–248, 1980.
[10]  M. S. Tairou, La tectonique tangentielle panafricaine au Nord-Togo [Ph.D. thesis], Université de Lomé, 2006.
[11]  P. Affaton, P. Gaviglo, and A. Pharisat, “Réactivation du craton ouest-africain au panafricain : paléocontraintes déduites de la fracturation des grès néoprotérozo?ques de Karey Gourou (Niger, Afrique de l’Ouest),” Comptes Rendus de l'Académie des Sciences, vol. 331, pp. 609–614, 2000.
[12]  P. Affaton, J. P. Gelard, and N. Simpara, “Paléocontraintes enregistrées par la fracturation dans l’unité structurale de l’Atacora (Cha?ne Panafricaine des Dahomeyides, Togo),” Comptes Rendus de l'Académie des Sciences, vol. 312, pp. 763–768, 1991.
[13]  M. S. Tairou, P. Affaton, J.-P. Gélard, R. Aite, and B. E. Sabi, “Panafrican brittle deformation and palaeostress superposition in northern Togo (West Africa),” Comptes Rendus—Geoscience, vol. 339, no. 13, pp. 849–857, 2007.
[14]  L. Latouche and J. Fabre, “Le Précambrien du craton ouest-africain,” in Géologie du Sahara Occidental et Central. Protérozo?que Inférieur de la Dorsale de Guinée, J. Fabre, Ed., vol. 108 of Tervuren, African Geosciences, pp. 15–72, Musée Royale de l’Afrique Centrale, Belgique, 2005.
[15]  B. Bessoles, “Géologie de l’Afrique,” Le craton Ouest Africain. Mém. BRGM 88, 403p, 1977.
[16]  E. K. Agyei, J. E. J. M. Van Landewijk, R. L. Armstrong, J. E. Harakal, and K. L. Scott, “RbSr and KAr geochronometry of South Eastern Ghana,” Journal of African Earth Sciences, vol. 6, no. 2, pp. 153–161, 1987.
[17]  W. Hirdes and D. W. Davis, “First U-Pb zircon age of extrusive volcanism in the Birimian Supergroup of Ghana/West Africa,” Journal of African Earth Sciences, vol. 27, no. 2, pp. 291–294, 1998.
[18]  F. Kalsbeek, P. Affaton, B. Ekwueme, R. Frei, and K. Thrane, “Geochronology of granitoid and metasedimentary rocks from Togo and Benin, West Africa: comparisons with NE Brazil,” Precambrian Research, pp. 218–233, 2012.
[19]  S. B. Dampare, T. Shibata, D. K. Asiedu, S. Osae, and B. Banoeng-Yakubo, “Geochemistry of Paleoproterozoic metavolcanic rocks from the southern Ashanti volcanic belt, Ghana: Petrogenetic and tectonic setting implications,” Precambrian Research, vol. 162, no. 3-4, pp. 403–423, 2008.
[20]  N. R. Junner, Geology of the Gold Coast and Western Togoland with Revised Geological Map, Gold Coast Geological Survey Bulletin, 1940.
[21]  R. Trompette, “La cha?ne panafricaine des Dahomeyides et le bassin des volta (bordure SE du craton Ouest-Africain),” Mém. B.R.G.M., 92, pp. 9–62, 1980.
[22]  B. Amard and P. Affaton, “Découverte de Chuaria circularis (Acritarche) dans le bassin des Volta (Haute Volta et Bénin, Afrique de l’Ouest). Age protérozo?que terminal de la formation de la Pendjari et de la tillite sous-jacente,” Comptes Rendus—Academie des Sciences II, vol. 299, no. 14, pp. 975–980, 1984.
[23]  B. Amard, “Chuaria pendjariensis n. sp., acritarche du bassin des Volta, Bénin et Burkina-Faso, Afrique de l’Ouest : un taxon nouveau du Cambrien inférieur,” Comptes Rendus—Academie des Sciences II, vol. 324, no. 6, pp. 477–483, 1997.
[24]  P. Affaton, L. Aguirre, and R.-P. Ménot, “Thermal and geodynamic setting of the Buem volcanic rocks near Tiélé, Northwest Bénin, West Africa,” Precambrian Research, vol. 82, no. 3-4, pp. 191–209, 1997.
[25]  M. Deynoux, P. Affaton, R. Trompette, and M. Villeneuve, “Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa,” Journal of African Earth Sciences, vol. 46, no. 5, pp. 397–426, 2006.
[26]  N. Simpara, J. Sougy, and R. Trompette, “Lithostratigraphie et structure du Buem unité externe de la chaine panafricaine des Dahomeyides dans la region de Bassar (Togo),” Journal of African Earth Sciences, vol. 3, no. 4, pp. 479–486, 1985.
[27]  M. Caen-Vachette, K. J. M. Pinto, and M. Roques, “Plutons éburnéens et métamorphisme dans le socle cristallin de la cha?ne panafricaine au Togo et au Bénin,” Revue de Geographie Physique et de Geologie Dynamique, vol. 21, no. 5, p. 351, 1979.
[28]  K. Attoh, R. D. Dallmeyer, and P. Affaton, “Chronology of nappe assembly in the Pan-African Dahomeyide orogen, West Africa: evidence from 40Ar/39Ar mineral ages,” Precambrian Research, vol. 82, no. 1-2, pp. 153–171, 1997.
[29]  Y. Agbossoumondé, R.-P. Ménot, J.-L. Paquette, S. Guillot, S. Yéssoufou, and C. Perrache, “Petrological and geochronological constraints on the origin of the Palimé-Amlamé granitoids (South Togo, West Africa): a segment of the West African craton paleoproterozoic margin reactivated during the Pan-African collision,” Gondwana Research, vol. 12, no. 4, pp. 476–488, 2007.
[30]  K. Attoh, “Dahomeyides in Southern Ghana: evidence for oceanic closure and crustal imbrication in a Pan—Africa,” Mern. C.I.F.E.G. vol. 22, pp. 159–164, 1990.
[31]  M. S. Tairou, P. Affaton, B. E. Sabi, and K. F. Seddoh, “Tectono-metamorphic evolution of the Mo and Kara-Niamtougou Orthogneissic Suites, Northern Togo,” Global Journal of Geological Sciences, vol. 7, no. 2, pp. 93–100, 2009.
[32]  M. El-Hadj Tidjani, P. Affaton, P. Louis, and A. Socohou, “Gravity characteristics of the Pan-African Orogen in Ghana, Togo and Benin (West Africa),” Journal of African Earth Sciences, vol. 7, no. 24, pp. 241–258, 1997.
[33]  Y. Agbossoumonde, R.-P. Menot, and S. Guillot, “Metamorphic evolution of Neoproterozoic eclogites from south Togo (West Africa),” Journal of African Earth Sciences, vol. 33, no. 2, pp. 227–244, 2001.
[34]  K. Attoh and J. Morgan, “Geochemistry of high-pressure granulites from the Pan-African Dahomeyide orogen, West Africa: constraints on the origin and composition of the lower crust,” Journal of African Earth Sciences, vol. 39, no. 3–5, pp. 201–208, 2004.
[35]  Y. Agbossoumonde, Les complexes ultrabasiques de la cha?ne panafricaine au Togo (Axe Agou—Atakpamé, Sud-Togo). Etude pétrographique, minéralogique et géochimique [Ph.D. thesis], Université Jean Monnet, St. Etienne, France, 1998.
[36]  R. P. Ménot, Y. Agbossoumondé, S. Guillot, and G. Duclaux, “Pan-African subduction-collision event evidenced by high-P coronas in metanorites from the Agou massif (Southern Togo),” Precambrian Research, vol. 135, no. 1-2, pp. 1–21, 2004.
[37]  B. E. Sabi, Etude pétrologique et structurale du Massif Kabyè, Nord-Togo [Ph.D. thesis], Université de Lomé, 2007.
[38]  K. Attoh and P. M. Nude, “Tectonic significance of carbonatites and ultrahigh-pressure rocks in the Pan-African Dahomeyide suture zone, southeastern Ghana,” in The Boundaries of the West African Craton, N. Ennih, J.-P. Liégeois, et al., Eds., vol. 297 of Special Publications, pp. 217–231, Geological Society, London, UK, 2008.
[39]  M. G. Abdelsalam, J.-P. Liégeois, and R. J. Stern, “The saharan metacraton,” Journal of African Earth Sciences, vol. 34, no. 3-4, pp. 119–136, 2002.
[40]  M. Caen-Vachette, “Age pan-africain des granites de Sinendé, Save et Fita (Dahomey),” Comptes Rendus de l'Académie des Sciences, pp. 1793–1795, 1975.
[41]  P. Affaton, A. Kr?ner, and K. F. Seddoh, “Pan-African granulite formation in the Kabye Massif of Northern Togo (West Africa): Pb-Pb zircon ages,” International Journal of Earth Sciences, vol. 88, no. 4, pp. 778–790, 2000.
[42]  J. P. Petit, “Criteria for the sense of movement on fault surfaces in brittle rocks,” Journal of Structural Geology, vol. 9, no. 5-6, pp. 597–608, 1987.
[43]  F. Bergerat, Déformations cassantes et champs de contrainte tertiaires dans la plate-forme européenne [Ph.D. thesis], University Pierre and Marie Curie, Paris, France, 1985.
[44]  J. Angelier, “Tectonique cassante et néotectonique,” Annales de la Société Géologique de Belgique, vol. 112, no. 2, pp. 283–307, 1990.
[45]  M. O. A?te, Analyse de la microfracturation et paléo-contraintes dans le Néocène post-nappes de Grande Kabylie (Algérie) [Ph.D. thesis], Université du Maine, 1994.
[46]  C. Castaing, C. Triboulet, J. L. Feybesse, and P. Chevremont, “Tectonometamorphic evolution of Ghana, Togo and Benin in the light of the Pan-African/Brasiliano orogeny,” Tectonophysics, vol. 218, no. 4, pp. 323–342, 1993.
[47]  U. Wenmenga, M. Kecir, and P. Affaton, “Distribution des filons de dolérite d’après les interprétations géologiques de données aéromagnétiques et leur signification géodynamique (Burkina Faso, Craton ouest africain),” Bulletin du Service Géologique National, vol. 20, no. 2, pp. 254–261, 2009.
[48]  M. Popoff, “Du Gondwana à l'atlantique sud: les connexions du fossé de la bénoué avec les bassins du Nord-Est brésilien jusqu'à l'ouverture du golfe de Guinée au crétacé inférieur,” Journal of African Earth Sciences, vol. 7, no. 2, pp. 409–431, 1988.
[49]  M. K. Mensah, “On the question of the age of Sekondi Series Upper Devonian or Lower Carboniferous rocks of Ghana,” Ghana Journal of Science, vol. 2, no. 33, pp. 134–139, 1973.
[50]  J. P. Sylvain, J. Collart, A. Aregba, and S. Godonou, “Notice explicative de la carte géologique 1/500.0000è du Togo,” Mém. 6, D.G.M.G./B.N.R.M., Lomé—Togo, 120p, 1986.
[51]  Y. D. Da Costa, Biostratigraphie et paléogéographie du basin sédimentaire c?tier du Togo [Ph.D. thesis], Université de Lomé, Togo, 2005.
[52]  A. A. Antobreh, J. I. Faleide, F. Tsikalas, and S. Planke, “Rift-shear architecture and tectonic development of the Ghana margin deduced from multichannel seismic reflection and potential field data,” Marine and Petroleum Geology, vol. 26, no. 3, pp. 345–368, 2009.

Full-Text

Contact Us

service@oalib.com

QQ:3279437679

WhatsApp +8615387084133