Browsing by Author "Rosenfels, Ryan Carl"
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- ItemCharacterizing the fungurume 88 deposit in the tenke fungurume mining district: an unusual, high-grade, primary cobalt sulphide deposit(Stellenbosch : Stellenbosch University, 2021-12) Rosenfels, Ryan Carl; Von der Heyden, Bjorn; Stellenbosch University. Faculty of Science. Dept. of Earth Sciences.ENGLISH ABSTRACT: The Tenke Fungurume Mining (TFM) district, situated in the northern parts of the Central African Copperbelt (CACB), exhibits one of the most renowned clusters of sedimentary stratiform copper deposits across the globe. The Fungurume 88 deposit comprises one of these clusters and is also described as a Roan-cored escallies (or tectonic window) and is situated in the south-east of the TFM district. It does not outcrop anywhere but is juxtaposed against the overlying Fungurume 8 deposit. Drill core logging and assaying of holes that intersected both the Fungurume 8 and 88 deposits have indicated that the two deposits exhibit uniquely different Cu-Co grades. Furthermore, they show variation in host lithologies although exhibiting the same sequence stratigraphy. A particular difference and one which forms the major underpinning of this study is the presence of extremely high-grade cobalt mineralization in the form of carrollite (CuCo2S4) hosted within a dolomitic shale/mudstone of the SD- 1b subunit within the Fungurume 88 deposit. This subunit is typically barren in the Fungurume 8 deposit which in turn is composed of a dolomitic sandstone/siltstone. Moreover, the Fungurume 8 deposit along with the majority of deposits in the TFM district have been identified to exhibit sediments belonging to the Long Facies. Petrographic studies on the SD-1b subunit in the Fungurume 88 deposit revealed numerous sulphide textures including the stratiform, disseminated, jack vein and cross-cutting vein mineralization. The morphological traits observed have allowed these mineralization styles to be distinguished in a temporal context whilst LA-ICPMS trace element assessment has also allowed the geochemical grouping of these episodes of mineralization. These groupings of mineralization include an early (probably diagenetic) episode as well as a later (probably syn-tectonic) episode. Petrographic studies of the host rock not only confirm that the Fungurume 8 deposit exhibits sediments of the Long facies but reveal that the sediments of the Fungurume 88 deposit belong to a deeper water sedimentary facies – likely the Kalumbwe or Menda facies. These insights corroborate with thermodynamic modelling of Cu and particularly Co phases, have also proposed reasons for the metal segregation and zonation we see within the Fungurume 88 deposit. From the entire hypogene mineral suit of the CACB, carrollite is the dominant host for cobalt metal. Interestingly, however, there is little known about its geochemistry, crystallography and surface properties. Another avenue of this study addresses these aspects revealing the trace element contents of carrollite along with their effects on the structural configuration and surface chemistry. Overall, the carrollite samples studied here are Cu-rich and exhibit a unit cell parameter of 9.4845 Å. From the data presented in this study, the thermodynamic analysis, crystallographic data and Raman spectroscopy (surface chemistry) represent the first of their kind for naturally occurring carrollite samples. This data in conjunction with major and trace element geochemistry as well as petrography provides a description of as well as genetic model for, the Fungurume 88 deposit.