Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria
Primary, secondary and accessory minerals in tonalitic rocks from Iwo region of the Precambrian Basement Complex of Southwestern Nigeria were identified and analysed with the aim of determining the various processes involved during the crystallisation of magma. Thin sections of tonalite were prepare...
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Online Access: | https://doi.org/10.2478/rmzmag-2020-0006 |
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doaj-8ca1b050c06b4a4480503199865392712021-09-05T14:01:28ZengSciendoMaterials and Geoenvironment1854-74002020-07-01672798910.2478/rmzmag-2020-0006rmzmag-2020-0006Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, NigeriaOziegbe E.J.0Ocan O.O.1Buraimoh A.O.2Department of Geosciences, Faculty of Science, University of Lagos, NigeriaDepartment of Geological Science, College of Science, Engineering and Technology, Osun State University, NigeriaDepartment of Geosciences, Faculty of Science, University of Lagos, NigeriaPrimary, secondary and accessory minerals in tonalitic rocks from Iwo region of the Precambrian Basement Complex of Southwestern Nigeria were identified and analysed with the aim of determining the various processes involved during the crystallisation of magma. Thin sections of tonalite were prepared and studied with the aid of a petrographic microscope. The mineral assemblages observed are biotite, plagioclase, alkali-feldspar, amphiboles, pyroxene, quartz, muscovite and chlorite. Allanite, titanite, apatite and zircon occur as accessory minerals. Muscovite and chlorite are found to be secondary minerals. The mineral allanite has a characteristic form of zoning and shows evidence of metamictisation, and is surrounded by dark-coloured biotite having radioactive haloes. Titanite is anhedral to subhedral crystals and forms reaction rim round opaque minerals. Plagioclase shows evidence of compositional zoning as well as plastic deformation of the twin lamellae. The allanite observed is primary in nature and has undergone radioactive disintegration; chlorite and muscovite are formed by secondary processes of chloritization and sericitisation, respectively. The tonalite is formed as a result of rapid cooling of magma close to the Earth's surface.https://doi.org/10.2478/rmzmag-2020-0006zoningtitaniteradioactive haloeschloritizationsericitisationconarnosttitanitradioaktivni halokloritizacijasericitizacija |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Oziegbe E.J. Ocan O.O. Buraimoh A.O. |
spellingShingle |
Oziegbe E.J. Ocan O.O. Buraimoh A.O. Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria Materials and Geoenvironment zoning titanite radioactive haloes chloritization sericitisation conarnost titanit radioaktivni halo kloritizacija sericitizacija |
author_facet |
Oziegbe E.J. Ocan O.O. Buraimoh A.O. |
author_sort |
Oziegbe E.J. |
title |
Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria |
title_short |
Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria |
title_full |
Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria |
title_fullStr |
Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria |
title_full_unstemmed |
Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria |
title_sort |
petrography of allanite-bearing tonalite from iwo region, osun state, nigeria |
publisher |
Sciendo |
series |
Materials and Geoenvironment |
issn |
1854-7400 |
publishDate |
2020-07-01 |
description |
Primary, secondary and accessory minerals in tonalitic rocks from Iwo region of the Precambrian Basement Complex of Southwestern Nigeria were identified and analysed with the aim of determining the various processes involved during the crystallisation of magma. Thin sections of tonalite were prepared and studied with the aid of a petrographic microscope. The mineral assemblages observed are biotite, plagioclase, alkali-feldspar, amphiboles, pyroxene, quartz, muscovite and chlorite. Allanite, titanite, apatite and zircon occur as accessory minerals. Muscovite and chlorite are found to be secondary minerals. The mineral allanite has a characteristic form of zoning and shows evidence of metamictisation, and is surrounded by dark-coloured biotite having radioactive haloes. Titanite is anhedral to subhedral crystals and forms reaction rim round opaque minerals. Plagioclase shows evidence of compositional zoning as well as plastic deformation of the twin lamellae. The allanite observed is primary in nature and has undergone radioactive disintegration; chlorite and muscovite are formed by secondary processes of chloritization and sericitisation, respectively. The tonalite is formed as a result of rapid cooling of magma close to the Earth's surface. |
topic |
zoning titanite radioactive haloes chloritization sericitisation conarnost titanit radioaktivni halo kloritizacija sericitizacija |
url |
https://doi.org/10.2478/rmzmag-2020-0006 |
work_keys_str_mv |
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