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P. Bowden; J. A. Kinnaird:

Geology and Mineralization of the Nigerian Anorogenic Ring Complexes

1984. 65 pages, 10 figures, 10 tables, 5 plates, 1 map, 17x24cm, 250 g
Language: English

(Geologisches Jahrbuch Reihe B, Band B 56)

ISBN 978-3-510-96289-1, paperback, price: 24.00 €

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Contents

Preface top ↑

The geological map which accompanies this explanation was compiled by J. A. KINNAIRD with assistance from C. A. ABERNETHY, and other research workers. The individual names are detailed in the footnotes to the map.

The map was cartographically drawn by A. W. GATRELL of Cartographic Services, Cirencester, and printed by JOHN BARTHOLOMEW, Edinburgh. The finance for producing the map was generously provided by the Overseas Development Ministry as an additional grant to research scheme R2679.

The text was compiled by P. BOWDEN and J. A. KTNNAIRD based upon notes, sample collections, and constructive criticisms from E. C. IRE, S. I. ABAA, U. M. TURAKI, C. A. ASERNETHY, J. N. BENNETT, and D. C. TURNER. Other individuals, and Mining Companies, who have substantially contributed to the map are listed in the left hand column beneath the geological information for each ring complex. The various sources of information used to compile the map are given briefly as footnotes, and more substantially within the reference list at the end of this article.

The Nigerian Mining Corporation, the Nigerian Mining Companies and the Nigerian Geological Survey gave access to field areas and provided many unpublished reports. Without the continued help of the Nigerian Government the completion of the work reported here would not have been possible.
Extents of the map are approx:
Longitude: 8,25 ° W - 10.25 ° W Latitude: 8,5 ° S - 11,9 ° S

Contents top ↑


1. Introduction 8

2. Basement Rocks and Palaeozoic Pegmatites 9
2.1 Nigerian basement 9
2.2 Palaeozoic pegmatites 9
2.3 Plate tectonic setting 13
3. Nigerian Anorogenic Ring Complexes 13
3.1 Age progressions of the Nigerian subvolcanic centres 13
3.2 Volcanic rocks 15
3.2.1 Basic volcanic rocks 15
3.2.2 Intermediate volcanic rocks 16
3.2.2.1 Alkaline suite16
3.2.2.2 Andesitic suite 16
3.2.3 Acid volcanic rocks 17
3.2.4 Chemical variations 17
3.3 Sedimentary rocks 18
3.4 Volcanic feeder intrusions 18
3.4.1 Cone sheets 18
3.4.2 Ring dykes 18
3.4.3 "Cupola" form 19
3.5 Subvolcanic intrusions 19
3.5.1 Basic intrusive rocks 20
3.5.2 Intermediate subvolcanic series 20
3.5.3 Granitic rocks 21
3.5.4 Petrological classification 22
3.5.5 Chemical variations 23
3.5.6 Fayalite hedenbergite granite 24
3.5.7 Hornblende biotite granite 24
3.5.8 Ferrorichterite arfvedsonite granite 25
3.5.9 Riebeckite annite granite 25
3.6 Albite granites and dispersed mineralisation 26
3.6.1 Zinnwaldite albite granite: columbite type 27
3.6.2 Arfvedsonite albite granite: pyrochlore type 27
3.7 Biotite granite and vein controlled mineralisation 29
3.7.1 Sodic metasomatism (albitization) 30
3.7.2 Potassic metasomatism (microclinization) 33
3.7.3 Acid metasomatism (greisenization) 34
3.7.4 Mineralization in biotite granite 35
3.7.5 Mineralization adjacent to volcanic cover 36
3.7.6 Mineralization adjacent to the Pan African "basement" 37
3.8 Mesozoic pegmatites 37
4. Superficial Cover 38
4.1 Alluvial and eluvial mineralization 38
4.2 Cretaceous rocks in the Benue Valley 39
4.2.1 Cretaceous sediments 39
4.2.2 Placer deposits 41
4.2.3 Cretaceous igneous activity 41
4.2.4 Cretaceous lead/zinc mineralisation 42
4.3 Tertiary rocks 44
4.3.1 Tertiary magmatism 44
4.3.2 Tertiary: Kerri-Kerri Formation 44

4.3.3 Mineralization 45
4.4 Quaternary rocks 45
4.4.1 Quaternary magmatism 45
4.4.2 The Chad formation and Quaternary dunefield 47
4.4.3 Economic importance of the Quaternary 47
5. References 48