地球科学と気候変動ジャーナル

抽象的な

Petrography and Mineralogy of Manganese Nodules around Madaka, Sheet 143, North Central, Nigeria

AKINTOLA Ojo Adeoye, NAJIME Tavershima, ADELEYE Rita Adeola, OLAOLORUN Amos Olusola, OGUNLEYE Paul Olusegun, ABUBAKAR Ismail Yusuf

Petrographical and mineralogical characterization of manganese nodules around Madaka, north central Nigeria has been examined using ore microscopy and X-ray Diffraction for the clay in the study area. The study area is underlain by rocks of the Nigerian Basement Complex. Some of the rocks in the area show metamorphic imprints, indicative of various degree of deformation they have suffered. These rocks comprise of gneisses (migmatitic gneiss, banded gneiss and granitic gneiss), the metasediments (kyanite-sillimanite schist, semi-pelitic schist; amphibolites, talcose rock, quartzite, and phyllite) and the granitic rocks (granodiorite, fine-medium-grained granites and porphyritic granite). Manganese nodules were found as concretions of different size dispersed in a variegated clay as hosted by kyanite silimanite schist. Two importance varieties of Mn nodules (red and brown) occur in the study area. The ore microscopy of manganese nodules reveals spalerite, birnessite, jianshuite, and pyrolusite (Mn oxides) as major minerals. The gauges in the studied nodules constitute calcite, hematite, a trace of quartz and an opaque mineral (pyrite). The X-ray Diffraction of the clay indicates the presences of Illite/mica, smectites and kaolinite/halloysite as major minerals. Traces of mn and quartz were observed as gauge in the clay. The mn nodules from Madaka are apparently controlled by physico-chemical factors (environment, heat and water) in the area. The source of the manganese nodules around Madaka area is at a considerable distance and consisted probably of a moderately basic igneous or metamorphic rock, which underwent disintegration, leaching and, the manganese nodules being transported in solution to its present state under influence of redox reaction through hydrothermal process.