Abstract
Abstract Precambrian supracrustal rocks from the Oban massif in southeastern Nigeria include a succession of deformed and metamorphosed metasediments (phyllites, mica schists and paragneisses) and metavolcanic rocks (amphibolites and dolerites). These are intruded by various granitoids ranging in composition from syenite and monzonite to tonalite. Metamorphic grade ranges from greenschist to upper amphibolite and locally, granulite grade and increases from west to east across the Oban massif. Metasediments have major and trace element characteristics of pelites and graywackes, and most metavolcanic and plutonic rocks are calc-alkaline. Rb-Sr whole-rock isochron ages obtained in this study are 1313 ± 37 Ma from homogeneous amphibolites (i = 0.7032); 527 ± 16 Ma and 676 ± 26 Ma from kyanite-sillimanite schists (i = 0.7088 and 0.7068, respectively); 784 ± 31 Ma from a banded amphibolite (i = 0.7059); and 510 ± 11 Ma from a migmatitic gneiss (i = 0.7112). These ages are tentatively interpreted as regional metamorphic episodes accompanying Kibaran (1300-1000 Ma) and Pan-African (800-500 Ma) orogenic events. The Pan-African Rb-Sr ages probably reflect collision of the West African craton with the Tuareg shield at about 600 Ma.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
