Characterization and Genesis of Kulfamba Manganese - Iron Occurrence, North Wollo, Ethiopia
No Thumbnail Available
Date
2020-06-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The Kulfamba Manganese-Iron occurrence is located in the top parts of Wollo plateau, northern Ethiopia, about 83 km west of Woldia. The main purpose of the research is to characterize and determine the origin of the ore body. To accomplish this secondary data collection, field observation, rock and ore analysis, and data presentation and interpretation methods have been applied. The geology of the study area is mainly characterized by presence of volcanic rocks and terrestrial sedimentary rock such as sandstone and mudrock. The ore body occurs within the volcano-sedimentary sub-basin associated with most probably late Oligocene intertrappean beds.
In order to define the genesis of the ore body, field observation, petrographic and geochemical examinations were undertaken. The field observation informs that the ore body is found in the form of stratabound - stratiform, vein, concretion and coating. From these, the layered ore is prominent over the other morphology. Based on petrographic observation, manganese oxide (mainly pyrolusite), hematite and goethite have been identified as ore minerals. Similarly, colloform growth banding, well developed crystals, vein fillings structures and secondary replacement are the ore mineral textures.
Geochemically, the mean Fe/Mn ratio of the upper and lower parts of the ore body shows strong fractionation of Fe and Mn, which are 0.045 and 20.52 respectively. The concentration of Ba is also high in the Mn-rich part, which is >10000 ppm. Contrary, the average concentrations of heavy metal such as Co, Ni and Cu have been very low in the ore body. The mean ΣREE concentrations of Mn and Fe ore body are extremely high, which is 1839.8 and 3056.2 ppm respectively. Likewise, the ΣLREE/ΣHREE ratios of the ore body exhibit high concentrations of LREE over HREE. The primitive-mantle-normalized diagram of both whole rock and ore body samples reveals the presence of slight negative Eu anomalies, and both positive and negative Ce anomalies. Therefore, the different investigation suggests that Kulfamba Mn-Fe occurrence is formed by mixing of hydrothermal and sedimentary processes. In addition, the occurrence of Mn - Fe ore in the form of concretion and coating reveals a contribution of secondary weathering process later on.
Description
Keywords
Kulfamba, Manganiferous, Terrestrial Bed, Genesis and Morphology