GEOLOGY, GEOCHEMISTRY AND STRUCTURAL CONTROLS OF BADAFI PEGMATITE FIELD, PARTS OF KABO SHEET 80 AND IKARA SHEET 103, NW NIGERIA
GEOLOGY, GEOCHEMISTRY AND STRUCTURAL CONTROLS OF BADAFI PEGMATITE FIELD, PARTS OF KABO SHEET 80 AND IKARA SHEET 103, NW NIGERIA
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Date
2017-07
Authors
NUHU, ABDULHAMID TILDE
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Abstract
The geology, geochemistry and structural studies of the granitoids from Badafi area in
northwestern Nigeria was carried out. This is aimed at determining the structural setting,
petrogenesis and mineralization potential of the rocks in the area. The study area is underlain by
migmatite, migmatitic gneiss, granites, aplite and pegmatites. The granitoids vary in texture and
composition and comprises of granodiorite, hornblende biotite granite, porphyritic biotite
granite, coarse grained biotite granite, medium grained biotite granite and pegmatites. Different
generations of pegmatites were mapped in the area and these are divided in to barren with repect
to rare metal and mineralized types. The mineralized pegmatites are rich in beryl and they strike
in NNW-SSE and NE-SW directions, while the barren pegmatites strike mainly in ENE-WSW
direction. Analysis of geochemical data revealed that both migmatite and migmatitic gneiss are
peraluminous and have high calc-alkaline affinity. Plots of TiO2 versus SiO2 discrimination has
shown that they are both orthogneisses (were derived from igneous protolith). On a REE pattern,
the migmatite is characterized by slightly fractionated REE with no Eu anomaly but migmatitic
gneiss show slight enrichment of LREE and depletion in HREE with weak Eu anomaly. The
mineralogical composition of the granitoids such as presence of hornblende and iron-oxide
(probably magnenite) couple with the geochemical data such as high Na2O suggest that the
granitoids belong to calc-alkaline, I-type, metaluminous to slightly peraluminous granitoids,
derived from partial melting of an igneous protolith. The mineralized pegmatites are
characterized by enrichment of some large ion lithophile elements such as Rb and Cs, typically
found in fractionated pegmatites. On the K/Rb versus Cs discrimination diagram the pegmatites
plot in the field typical of beryl mineralized pegmatites. This is in agreement with the
occurrences of beryl mineralization as observed in the pegmatites. The pegmatites also show
marked similarity with some beryl mineralized pegmatites in Cross Lake area of central
Manitoba. The beryl mineralization in the pegmatites is largely associated with late stage
albitization and occurs within vugs (pockets). Evidence from REE pattern suggests that the
pegmatites are not co-magmatic with their host post-collision granitoids, but were formed from
highly fractionated and fluid-saturated residual melt of aplitic composition.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE DEGREE IN GEOLOGY DEPARTMENT OF GEOLOGY, FACULTY OF PHYSICAL SCIENCE, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
GEOLOGY,, GEOCHEMISTRY,, STRUCTURAL CONTROLS,, BADAFI PEGMATITE FIELD,