THE GEOLOGY AND GEOCHEMISTRY OF BARXTE MINERALISATION IN THE AZARA AREA, MIDDLE BENUE TROUGH, NIGERIA.

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Date
1985-09
Authors
OMADA, JOSEPH ITAH
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Abstract
The rocks of the Azara area are made up of sandstones, shale and shay mud-stones, and lime-stones of the Awe formation, and sandstones of the Keana formation. Dacie, a volcanic rock, also occurs in the study area. Mineralization in the Azara area is in the form of brine springs and battery deposits. Both are lithological and structurally controlled. All the brine springs are located on the same alignment on an anticlerical axis of a ENE-WSW fold that transcends the study area. Analytical results of the elements in the brine springs shows that they are marine in origin and are solutions of halite derived from an evaporate. The evaporate are associated with the transitional Awe formation of Monomania age but the brine springs seen on the surface are structurally related to the fractures that developed as a result of tension caused by the compressive stresses of the Antoninus folding episode in the Benue Trough. The barrettes occur as fracture filling veins mostly in the sandstones of the Keana Formation at the nose and flanks of the ENE-WSW fold. The barrettes are hydrothermal in origin. Within each vein system different generations of barrettes with sharp contacts occur. Analytical results and trends of the elements vi In the barrettes show that the barium in the hydrothermal solutions was immobilisers as a result of leaching, from misaligned basement rocks beneath the Cretaceous sedimentary cover. The presence of Cu suggests a temperature of 150 - 250°C. The Initial heat was supplied from volcanism in the study area. The barrettes are probably Campanologist in age. The evaporates and barrettes in the Azara area are not genetically related. Though the brine springs and the Pb-Zn renationalisation in the Benue trough are spatially related, investigation shows that they are not genetically related. Trace element studies only indicate that the battery renationalisation represents the last stages of the hydrothermal activity that gave rise to the Pb-Zn veins in the Benue trough.
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A thesis submitted to the postgraduate School, Ahmadu Bcllo University, in partial fulfillment of the requirements for the degree of M.Sc. Geology (Mineral Exploration) Department of Geology Faculty of Science Ahmadu Bello University, Zaria SEPTEMBER, 1985
Keywords
GEOLOGY,, GEOCHEMISTRY,, BARXTE,, MINERALISATION,, AZARA AREA,, MIDDLE,, BENUE TROUGH,, NIGERIA.
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