Current state of knowledge of the gold mineralization at Imonga-Saramabila, Maniema (DR Congo): a petrographic and mineralogical study of the mineralized vein system
Julie DE GROOTE, Inge Cools, S. Wouters, P. Muchez, Stijn Dewaele
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引用次数: 0
Abstract
The Great Lakes area in Central Africa forms a large metallogenic province that hosts important deposits of gold mineralization. We present a petrographic, mineralogical and geochemical study of unique borehole samples from the Imonga-Saramabila gold deposit, a historical mine site located in the Maniema Province (DR Congo) in the Karagwe-Ankole belt (KAB) in the Great Lakes area and one of the only places in the Maniema province with accessible boreholes allowing to study the mineralization. The samples are metasedimentary rocks belonging to the Mesoproterozoic Kivu Supergroup, with bedding-parallel meta-igneous rocks. These rocks have undergone upper greenschist to lower amphibolite facies metamorphism, based on the presence of andalusite and chiastolite porphyroblasts, and are affected by hydrothermal alteration. The porphyroblasts formed during peak metamorphism and posterior to a first vein generation. Three additional vein generations were identified at Imonga based on crosscutting relationships, with the second and third events overprinting the porphyroblasts by intense chloritization, and associated with sulfide mineralization. The fourth vein generation is again barren. The first veining event formed pre-folding and the three subsequent generations postdate folding, as concluded based on the relationship of the veins with the cleavage. Only one important folding event is proposed based on the development of only one cleavage. Gold occurs as free gold or is included in pyrite in the second (and maybe third) vein generation. Based on the paragenesis, structural characteristics, and the link between veining and metamorphic minerals, the gold mineralization at Imonga is interpreted to be linked to the early Neoproterozoic (~980 Ma) compressional deformation event, associated with the amalgamation of the Rodinia supercontinent.
期刊介绍:
Geologica Belgica is a Belgian journal that welcomes papers concerning all aspects of the earth sciences, with a particular emphasis on the regional geology of Belgium, North West Europe and central Africa. Papers not dedicated to the geology of Belgium, North West Europe and central Africa are only accepted when one of the authors is linked to a Belgian University or Institution. Thematic issues are highly appreciated. In this case, guest editors take in charge the selection of the manuscripts and the subject of the papers can be enlarged. The journal is in open access.
Submitted manuscripts should be concise, presenting material not previously published. The journal also encourages the publication of papers from Belgian junior authors. Short letters are accepted. Papers written in English are preferred. Each mansucript will be reviewed by at least two reviewers.