GEOLOGY AND GEOCHEMISTRY OF SHA AREA, PART OF SHEET 189 KURRA SW, NORTH-CENTRAL NIGERIA.
GEOLOGY AND GEOCHEMISTRY OF SHA AREA, PART OF SHEET 189 KURRA SW, NORTH-CENTRAL NIGERIA.
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Date
2022
Authors
YAHUZA, AHMAD MUAWIYA
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Abstract
The geology and geochemistry of Sha area, north central Nigeria was investigated solely to determine the nature of occurrence, petrography, geochemistry and evaluate the mineralization potential of the granitic pegmatites. The area was underlain by granitoid rocks. The granitoid varied in texture and mineralogy, they comprised of coarse - medium – fine grained biotite granite, diorite and pegmatites which occured as minor rock in form of dykes and knots. Field mapping on a scale of 1:50,000 and petrographic studies were carried out, while geochemical analysis of the granitoids, K feldspar and biotite extracted from pegmatites were undertaken using XRF and lithium metaborate/tetraborate fusion ICP-MS. Petrographic studies revealed that the major mineral in biotite granite are quartz, biotite, plagioclase, orthoclase. Analytical geochemical data showed that the rocks are peraluminous (A/CNK >1) to slightly meta luminous S-type granite. The pegmatites are commonly zoned and are hosted by biotite granite. Geochemical data further indicated that Rb, W, Cs, Y and Sn contents increases from the host granitoid inwards. The elements (Rb, W, Cs, and Y and Sn) increase with decreasing K/Rb and K/Cs ratio. Sn content ranged from 2-16ppm in feldspar and 555-696 ppm in biotite, Nb concentration also ranged from 2-4 ppm in Kfeldspar and 391-684 in biotite extracted from pegmatites. The variations are consistent with enrichment via fractionation processes. The pegmatites represented the last stage fraction of liquid of fractional crystallization of the magma from which the rocks were formed. The potential of the pegmatites were evaluated using K/Rb and ratio below 100 is indicative of mineralization. The discrimination diagram Rb vs K/Rb, Cs vs K/Rb show limited ranged of fractionation thus suggesting that the pegmatites in Sha area belong to the rare metal mineralized pegmatite type.
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DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES AHMADU BELLO UNIVERSITY, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF A MASTER OF SCIENCE DEGREE IN GEOLOGY DEPARTMENT OF GEOLOGY, FACULTY OF PHYSICAL SCIENCES,AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA