The Birrimian System forms most of the exposed Precambrian shield of West Africa. About half of Ghana is underlain by Birrimian metamorphic and granitic rocks. In the Dunkwa S. E. area (Field Sheet 48) of south-central Ghana, interlayered sedimentary and volcanic rocks were metamorphosed to greenschist and amphibolite facies. These sheared and tightly folded metamorphic rocks have incipient retrograde metamorphism of biotite and garnet to chlorite or hornblende to biotite. Two large intrusive bodies in the metamorphic terrain may be partly the result of granitization: (1) the Pra River complex, an albitized laccolith or sill, consisting of quartz monzonite, quartz diorite, and granodiorite; (2) the Twifu Praso complex of albite granite and granodiorite gneiss. All of the above rocks were folded along northeast-trending fold axes. Then a third granitic body, the Wuwu River albitized quartz monzonite, intruded and locally re-folded the older rocks. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/11974 |
| Date | 27 June 2011 |
| Creators | Fakundiny, Robert H. |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Format | electronic |
| Rights | Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
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