TITLE:
Metallogeny and Emplacement Conditions of Continental Terminal 3 (Ct3) Iron Formations of the Niamey Region (Western Niger)
AUTHORS:
Habsatou Ousmane, Karimou Dia Hantchi, Ibrahim Abdou Ali, Leyla Boubacar Hamidou, Aminou Abdoulaye Maâzou, Adiss Kamal Issifou Fatiou, Moussa Konaté
KEYWORDS:
Continental Terminal, Iron Ore Mineralization, Sedimentation Conditions, Oolites, Gœthites, Hardground
JOURNAL NAME:
Open Journal of Geology,
Vol.13 No.7,
July
26,
2023
ABSTRACT: This study aims to characterize the different
lithofacies of the Ct3 formation in the Niamey region, and to
determine the distribution of major and trace elements, in order to highlight
the conditions for the establishment of iron mineralization. A lithological
column, synthesizing sections of selected outcrops in the vicinity of Niamey,
was produced. The chemical compositions of the selected samples were determined
by X-ray fluorescence (XRF) spectrometry. Microscopic analysis of the thin
sections determined the gœthitic nature of the oolitic iron ore. The oolites
show a quartz, limonitic or gœthitic nucleus. Sometimes the nucleus is absent.
From a morphoscopic point of view, two types
of oolites have been distinguished: spherical-shaped and ellipsoidal-shaped
oolites. The oolites are either contiguous or disseminated, as the case may be,
in a limonitic to goethitic cement or in a fine sandstone matrix. The larger
oolites (pisolites) are relatively friable. They reflect the influence of a
relatively turbulent to submerged environment. The hardground of the
iron mineralized horizons are covered by quartz grains. They are indicative of
a submerged or emergent environment. X-ray fluorescence analysis shows high Fe2O3 contents (50% to 80%) and variable contents of major elements SiO2,
Al2O3, TiO2, MnO, MgO, CaO, K2O and
P2O5 associated with certain trace elements such as Th,
U, V, Y, Zn, Zr and As. The results of the study are an important tool for
decision-makers to adopt effective prevention/remediation measures for
groundwater contamination in the Continental terminal aquifer systems.