Metallogeny and Emplacement Conditions of Continental Terminal 3 (Ct³) Iron Formations of the Niamey Region (Western Niger)  

作　　者：Habsatou Ousmane Karimou Dia Hantchi Ibrahim Abdou Ali Leyla Boubacar Hamidou Aminou Abdoulaye Maâzou Adiss Kamal Issifou Fatiou Moussa Konaté Habsatou Ousmane;Karimou Dia Hantchi;Ibrahim Abdou Ali;Leyla Boubacar Hamidou;Aminou Abdoulaye Maâzou;Adiss Kamal Issifou Fatiou;Moussa Konaté(Department of Geology, Faculty of Science and Techniques, Abdou Moumouni University, Niamey, Niger;Department of Geology, Faculty of Science and Techniques, Dan Dicko Dankoulodo University, Maradi, Niger;Department of Life and Earth Sciences, école Normale Supérieure (ENS), Abdou Moumouni University, Niamey, Niger;Department of Earth Sciences, Faculty of Science and Techniques, University of Abomey-Calavi, Abomey-Calavi, Benin)

机构地区：[1]Department of Geology, Faculty of Science and Techniques, Abdou Moumouni University, Niamey, Niger [2]Department of Geology, Faculty of Science and Techniques, Dan Dicko Dankoulodo University, Maradi, Niger [3]Department of Life and Earth Sciences, école Normale Supérieure (ENS), Abdou Moumouni University, Niamey, Niger [4]Department of Earth Sciences, Faculty of Science and Techniques, University of Abomey-Calavi, Abomey-Calavi, Benin

出　　处：《Open Journal of Geology》2023年第7期720-739,共20页地质学期刊（英文）

摘　　要：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.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.

关 键 词：Continental Terminal Iron Ore Mineralization Sedimentation Conditions Oolites Gœthites Hardground 

分 类 号：P61[天文地球—矿床学]