Petrographic Study of Mn-bearing Gondite (Birimian) of Téra Area in the Leo-Man Shield (West African Craton) in Niger.

• 영문명: Petrographic Study of Mn-bearing Gondite (Birimian) of Téra Area in the Leo-Man Shield (West African Craton) in Niger.
• 발행기관: 대한자원환경지질학회
• 저자명: Hamidou GARBA SALEY Moussa KONATÉ Olugbenga Akindeji OKUNLOLA
• 간행물 정보: 『자원환경지질』57권 1호, 25~39쪽, 전체 15쪽
• 주제분류: 자연과학 > 지질학
• 파일형태: PDF
• 발행일자: 2024.02.28

영문 초록

The Téra manganese deposit represents the most significant manganese mineralization discovered in Niger up today. The main host rocks of this ore are gondites, which are a garnet and quartz rich metamorphic rocks. The supergene weathering developed an alteration profile on these gondites. This study aims to identify the mineralogical composition of gondites and associated rocks, in order to highlight the origine of rocks and the manganese enrichment. The methodological approach adopted involved a field study followed by polarizing microscopic analysis using transmitted and reflected lights. Additionally, quantitative X-ray diffraction (XRD) analysis was performed to assess the manganese ore minerals present in the gondite and associated rocks, including mica schists, amphibolites, and quartzites. The petrographic study revealed a paragenesis characterized by the presence of kyanite, staurolites, garnets and plagioclases that are generally poikiloblasts with quartz and opaque minerals inclusions, emphasizing the internal schistosity which is planar, helicitic or microfolded. These features indicate a prograde metamorphism until high-pressure amphibolite facies conditions. These conditions are followed by greenschist facies conditions marked by calcite, epidote, muscovite, chlorite and muscovite assemblage which emphasizes the vertical tectonics. Depending on the alteration process, the manganese ore exhibit a granular texture at the bottom of the gondite hills, transitioning to a colloform texture towards the top, passing through the epigenization and replacement texture. The XRD analysis further revealed that the studied rocks originated from a volcanosedimentary complex, characterized by alternating marly, arenaceous and pelitic sequences associated with submarine exhalations.

목차

1. Introduction

2. Geological Settings

3. Material and Methods

4. Results

5. Discussions

6. Conclusion

Declaration of Competing Interest

Acknowledgements

References

키워드

manganese deposit Birimian gondite Téra Man shield