GEOLOGY OF SHEET 79 MALUMFASHI SOUTH EAST, GEOCHEMISTRY AND MINERALIZATION POTENTIAL OF TUDUN KAYA - DANZAU AREA NW, NIGERIA

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Date
2011-06
Authors
RUFA’I, SHAFI’U AHMAD
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Abstract
ABSTRACT Field mapping, petrographic and geochemical analysis of rocks in sheet 79, Malumfashi SE was carried out in this study. Field mapping on a scale of 1:50,000 reveals that the area is composed of banded gneiss, Older Granite, diorite as the major rock types. Pegmatite veins, aplite dykes and quartz veins occur as minor intrusives. Alluvium. Laterite and soil occur as superficial deposits. The pegmatite zone was further mapped on a scale of 1:10,000 for detailed study. Structural analysis indicates that some of the rocks are deformed, either folded or faulted trending N-S to NNE-SSW, which coincides with the disposition of the Pan African Basement structures. North- East trending fractures and faults were also documented and are exploited by most of the pegmatitic veins and dykes. Petrographic analysis using transmitted light microscopy shows that the granites contains quartz, feldspar(microcline) and biotites as the major minerals, the diorite is seen to contain oligoclase as the dominant feldspars with biotite, chlorite and quartz. The pegmatite also contains predominantly feldspar, quartz mica and beryl. The banded gneiss was highly weathered that they could not allow for a petrographic analysis of the rock. Geochemical analysis of eleven representative samples of the major rock types granite,diorite and the pegmatite from the study area was carried out at the Activation Laboratories Ontario, Canada. The analytical methods used by Actlabs include the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for major and trace element analysis, the Instrumental Neutron Activation Analysis (INAA) for trace and rare earth elements analysis. The major elements from the analysis shows SiO2 for Granites to be 72.3 – 74.3 wt%, Diorites 57.96 – 74.77 wt% and pegmatites 62.6 – 74.While K2O for granites is 4.71 – 4.85 wt%, diorite 4.39 -5.02 wt% and 0.86 – 9.64 wt% for the pegmatites. TiO2 in all the samples is between 0.01 -0.908 wt%. The trace element composition for all the samples was Ba 27.4 – 2073ppm, Sr 14.0 – 603, Rb 41.0 – 1000ppm, Cs 5.1 – 30ppm. The rare earth elements in the samples are Ce 4.6 – 107, Eu 0.05 – 2.07ppm. The granites were found to be peraluminous in nature and on a chondrite normalized REE pattern plots shows enrichment in LREE and a depletion in HREE. The Eu anomaly is negative viii and well pronounced typical of the other granitic rocks from other parts of northern Nigeria. The pegmatites also show an enriched LREE and a more enriched HREE with a negative Eu anomaly. The K/Rb ratio and a plot of the discrimination diagram K/Rb Vs Rb suggest only a slight enrichment of the REE in the pegmatites. An evolution model for the rock types and other intrusives in the study area is being proposed. As no major mineralization was observed on the major rock types yet the associated minerals most especially for the pegmatites could be exploited industrially, prospects for tapping the alluvium deposits, laterites and rock aggregates are high.
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DEPARTMENT OF GEOLOGY AHMADU BELLO UNIVESITY ZARIA - NIGERIA.
Keywords
GEOLOGY,, SHEET,, MALUMFASHI,, SOUTH,, EAST,, GEOCHEMISTRY,, MINERALIZATION,, POTENTIAL,, TUDUN,, KAYA,, DANZAU,, AREA,, NEW., NIGERIA.
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