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