Pan-African Orogeny in Northern Nigeria

Research Article| November 01, 1971 Pan-African Orogeny in Northern Nigeria PATRICIA McCURRY PATRICIA McCURRY Department of Earth Sciences, The Open University, Walton, Bletchley, Bucks, England Search for other works by this author on: GSW Google Scholar GSA Bulletin (1971) 82 (11): 3251–3262. https://doi.org/10.1130/0016-7606(1971)82[3251:POINN]2.0.CO;2 Article history received: 10 Jun 1971 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation PATRICIA McCURRY; Pan-African Orogeny in Northern Nigeria. GSA Bulletin 1971;; 82 (11): 3251–3262. doi: https://doi.org/10.1130/0016-7606(1971)82[3251:POINN]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract An area of approximately 12,000 sq km of Precambrian to lower Paleozoic rocks around Zaria in northern Nigeria has recently been mapped for the first time. Results from this survey have been combined with limited data from adjacent areas to determine the nature of the Pan-African event in this part of Nigeria.A crystalline basement complex of gneisses, migmatites (Dahomeyan), and relicts of an ancient metasedimentary sequence (Birrimian) underlies most of the region. Infolded into this basement, as north-south-trending synclinoria, is a younger metasedimentary sequence (Ka-tangan) forming the remnants of an earlier, more extensive supracrustal cover. A suite of syntectonic to late tectonic granites and granodiorites (late Precambrian to lower Paleozoic) has intruded both the basement and its cover.The structure of the area is dominated by north-south trends typical over much of Nigeria. There is evidence to suggest that the whole area was affected by two successive phases of intense deformation resulting in tight isoclinal folding about (1) east-northeast-west-southwest, and (2) north-south axes. The crystalline basement was reactivated and the supracrustal cover regionally metamorphosed. Two phases of progressive metamorphism accompanied the deformations, which were separated and followed by static metamorphic phases. Pressure-temperature conditions of metamorphism appear to have remained fairly constant throughout, giving rise to a low pressure facies series similar to the Buchan type.Extensive migmadzation of the crystalline basement is believed to have accompanied the first deformation, followed by further differentiation during the second phase to produce homogeneous gneisses and intrusive granites. Jointing, fracturing, and faulting followed the orogeny, and a major northeast-southwest-trending transcurrent fault system crosses the area. It is obvious from the structural and metamorphic evidence that the Pan-African event reached the status of an orogeny in northwestern Nigeria. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.