THE STRUCTURE, PETROLOGY AND GEOCHEMISTRY OF THE TIBCHI YOUNGER GRANITE RING-COMPLEX, NIGERIA
THE STRUCTURE, PETROLOGY AND GEOCHEMISTRY OF THE TIBCHI YOUNGER GRANITE RING-COMPLEX, NIGERIA
| dc.contributor.author | IKE, ECHEFU CYRIACUS | |
| dc.date.accessioned | 2015-06-09T07:59:22Z | |
| dc.date.available | 2015-06-09T07:59:22Z | |
| dc.date.issued | 1979-09 | |
| dc.description.abstract | The 1 :50,000 geological map of the Tibchi Complex presented is characterised by a closed elliptical ring-dyke framework hitherto unpredicted by pioneer workers. Major rock units comprise a basalt - potassic granite suite. The structural history of the Complex involved a central shield volcano, succeeded by a caldera and fluidised intra-caldera volcanism. The model proposed is on the principle of positive magma pressure during both caldera formation and ring-dyke intrusion. With ash-fall tuff and rhyolite lavas resting directly on the subsided basement block within the ring-fracture, the Tibchi Complex shows the first clear exposure of the Jurassic landscape to be recorded in Nigeria. An olivine tholeiite - tholeiite - andesine basalt - trachyte sequence, and a microferrodiorite - microsyenite - granitic porphyries sequence are separately established but together appear to form a unified petrogenetic succession. The scarcity of modal plagioclase, and the low levels of calcium and magnesium, together with the extreme iron-enrichment,in the rocks,are accounted for. The petrology is complicated by various postmagmatic hydrothermal and metasomatic processes from which certain distinctive rock-types formed. These processes are described in full and explanations offered. Contact metamorphism previously unassociated with the Nigerian Younger Granites is recorded in a bifacial metamorphic aureole related to the biotite granite intrusion. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/6519 | |
| dc.language.iso | en | en_US |
| dc.subject | THE STRUCTURE, PETROLOGY AND GEOCHEMISTRY OF THE TIBCHI YOUNGER GRANITE RING-COMPLEX, NIGERIA | en_US |
| dc.subject | THE STRUCTURE, PETROLOGY AND GEOCHEMISTRY OF THE TIBCHI YOUNGER GRANITE RING-COMPLEX, NIGERIA | en_US |
| dc.title | THE STRUCTURE, PETROLOGY AND GEOCHEMISTRY OF THE TIBCHI YOUNGER GRANITE RING-COMPLEX, NIGERIA | en_US |
| dc.type | Thesis | en_US |