Structural Controls on Orogenic Gold Mineralization in High-Grade Metamorphic Rocks: Insights from the Nathenje Prospect, Central Malawi | ||
| Journal of Mining and Environment | ||
| مقاله 6، دوره 17، شماره 2، خرداد و تیر 2026، صفحه 487-500 اصل مقاله (14.11 M) | ||
| نوع مقاله: Original Research Paper | ||
| شناسه دیجیتال (DOI): 10.22044/jme.2025.16348.3183 | ||
| نویسندگان | ||
| Joshua Chisambi* 1؛ Leornard Kalindekafe2؛ Kettie Magwaza2؛ Ruth Mumba2؛ Martin Kameza2 | ||
| 1Department of Mining Engineering, Malawi University of Business and Applied Sciences: Blantyre, Malawi | ||
| 2Malawi Mining Investment Company (MAMICO), Lilongwe, Malawi | ||
| چکیده | ||
| The Nathenje region in central Malawi hosts significant gold mineralization within high-grade metamorphic rocks of the Mozambique Belt, yet remains underexplored despite extensive artisanal mining activity. The structural controls on primary bedrock gold mineralization within these high-grade metamorphic rocks remain poorly understood, limiting systematic exploration and resource development. We conducted integrated field mapping, structural analysis, petrographic examination, and geochemical sampling to characterize gold mineralization controls in the Nathenje prospect, central Malawi. Detailed structural measurements combined with stereographic analysis reveal three deformation phases, with gold mineralization predominantly associated with D₂ transpressional structures. Fire assay results demonstrate significant gold concentrations (0.15–5.0 g/t Au) in arsenopyrite-bearing quartz veins, with the highest grades systematically occurring at structural complexity zones. Petrographic analysis reveals native gold particles (5–50 μm) intimately associated with arsenopyrite along grain boundaries and within microfractures, indicating coupled precipitation processes. Critically, we identify a hierarchical structural control system operating from regional NE-SW trending shear zones to microscale sulphide boundaries, with fold hinges, dilutional jogs, and amphibolite-gneiss contacts yielding consistently higher gold grades (>3 g/t Au) than other structural settings. Our results establish the first comprehensive structural model for gold mineralization in central Malawi's metamorphic terrain and provide specific targeting criteria applicable to similar high-grade metamorphic environments throughout the East African Orogen. | ||
| کلیدواژهها | ||
| Shear zones؛ Fold hinges؛ Malawi Basement Complex؛ Pan-African Orogeny | ||
| مراجع | ||
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[1] Dill, H. (2007). A review of mineral resources in Malawi: With special reference to aluminium variation in mineral deposits. Journal of African Earth Sciences. vol. 47, pp. 153–173, 2007, doi: 10.1016/j.jafrearsci.2006.12.006.
[2] Chisambi,J.,& von der Heyden, B. (2019). Primary gold mineralization in the lisungwe valley area, kirk range, southern Malawi. South African Journal of Geology, vol. 122, no. 4, pp. 505–518, 2019, doi: 10.25131/sajg.122.0039.
[3] Chisambi, J., Haundi,T., & Tsokonombwe, G. (2020) Geologic structures associated with gold mineralization in the Kirk Range area in Southern Malawi. Open Geosciences, vol. 13, no. 1, pp. 1345–1357, 2021, doi: 10.1515/geo-2020-0304.
[4] Chisambi, J., von der Heyden, B., & Tshibalanganda, M. (2020). Gold Exploration in Two and Three Dimensions : Improved and Correlative Insights from Microscopy and X-Ray Computed Tomography. Minerals, pp. 1–20.
[5] Bloomfield.K., & Garson.M. (1965). The Geology of the Kirk Range-Lisungwe Valley Area. Bulletin No.17., The Government Printer, Zomba. Malawi.
[6] Malunga, G. (1992). Geochemical Exploration of Gold in the Likudzi Block, Geological Survey of Malawi. Geological Survey of Malawi, unpublished report.
[7] Chisambi, J., & von der Heyden, B. (2023). The origin and evolution of the ore-forming fluids at the Manondo-Choma gold prospect, Kirk range, southern Malawi. Open Geosciences, vol. 15, no. 1, 2023, doi: 10.1515/geo-2022-0494.
[8] Chisambi, J. & von der Heyden, B. (2019). Primary gold mineralization at Manondo – Choma area, Kirk range, Southern Malawi. South African Journal of Geology, no. 4.
[9] Chisambi, J.,Haundi, T., & von der Heyden, B. (2022). Aeromagnetic mapping of basement structures and gold mineralization characterization of Kirk range area, southern Malawi. International Journal of Mining and Geo-Engineering, vol. 56, no. 3, 2022, doi: 10.22059/IJMGE.2022.330117.594929.
[10] Haundi, T., Tsokonombwe, G., Ghambi, S., Mkandawire, T., & Kasambara, A. (2021). An Investigation of the Socio-Economic Benefits of Small-Scale Gold Mining in Malawi. Mining, vol. 1, no. 1, 2021, doi: 10.3390/mining1010003.
[11] Chisambi, J., Haundi, T., & Ghambi, S. (2023). Integrated interpretation of aeromagnetic and aero-radiometric data to delineate structures and hydrothermal alteration zones associated with Gold and Base metal Mineralization in Chitipa area, Northern Malawi. International Journal of Mining and Geo-Engineering, vol. 57, no. 3, 2023, doi: 10.22059/IJMGE.2023.354353.595027.
[12] Delvaux, D. et al., (2018). Late Neoproterozoic (Pan-African) reactivations in the Mesoproterozoic Karagwe- Ankole Belt (KAB) in Kivu (RDC), Rwanda and Burundi: chronological framework and paleostress field. in 6th International Geologica Belgica meeting.
[13] Fritz, H. et al.,(2013). Journal of African Earth Sciences Orogen styles in the East African Orogen : A review of the Neoproterozoic to Cambrian tectonic evolution. Journal of African Earth Sciences, vol. 86, pp. 65–106, doi: 10.1016/j.jafrearsci.2013.06.004.
[14] Stern, R. J. (2002). Crustal evolution in the East African Orogen : a neodymium isotopic perspective, vol. 34, pp. 109–117, 2002.
[15] Bloomfield, K., & Garson, M. (1965). The Geology of the Kirk Range-Lisungwe Valley Area. Ministry of Natural Resources. Geological Survey Department. Bulletin No.17., The Government Printer, Zomba. Malawi, 1965.
[16] Kroner, A., & Collins, A. (2001). The East African Orogen: New Zircon and Nd Ages and Implications for Rodinia and Gondwana Supercontinent Formation and Dispersal. Gondwana Research, no. 2, pp. 179–181, 2001.
[17] Sommer, H., & Kröner, A. (2013). Ultra-high temperature granulite-facies metamorphic rocks from the Mozambique belt of SW Tanzania. Lithos, vol. 170–171, pp. 117–143, 2013, doi: 10.1016/j.lithos.2013.02.014.
[18] Ring, U., Kröner, A., & Toulkeridis, T. (1997). Palaeoproterozoic granulite-facies meta-morphism and granitoid intrusions in the Ubendian-Usagaran Orogen ofnorthern Malawi, east-central Africa. Precambrian Reserch., vol. 85, 27–51.
[19] Bjerkgard, T., & Stein, H. (2008). The Niassa Gold Belt , northern Mozambique – A segment of a continental-scale Pan-African gold-bearing structure ?. Journal of African Earth Sciences, vol. 53, no. 1–2, pp. 45–58, 2009, doi: 10.1016/j.jafrearsci.2008.09.003.
[20] Bingen et al., (2009). “Geochronology of the Precambrian crust in the Mozambique belt in NE Mozambique , and implications for Gondwana assembly. Precambrian Res, vol. 170, pp. 231–255, 2009, doi: 10.1016/j.precamres.2009.01.005.
[21] Boyd et al.,( 2010). The Geology and Geochemistry of the East African Orogen In Northeastern Mozambique. Geological Society of South Africa, vol. 113, pp. 87–129, 2010, doi: 10.2113/gssajg.113.1.87.
[22] Macey et al., (2010). Mesoproterozoic geology of the Nampula Block , northern Mozambique : Tracing fragments of Mesoproterozoic crust in the heart of Gondwana. Precambrian Research. vol. 182, pp. 124–148, 2010, doi: 10.1016/j.precamres.2010.07.005.
[23] Ring, U & Kronner, A. (2002). Shear-zone patterns and eclogite-facies metamorphism in the Mozambique belt of northern Malawi , east-central Africa : implications for the assembly of Gondwana. Precambrian Res, vol. 116, pp. 19–56.
[24] Cardozo, N.,& Allmendinger, R. (2013). Spherical projections with OSXStereonet. Computure and Geosciences, vol. 51, 2013, doi: 10.1016/j.cageo.2012.07.021.
[25] Allmendinger, R. (2011). Stereonet 7,” Distribution.
[26] Goldfarb, R., & Groves, D. (2015). Orogenic gold : Common or evolving fl uid and metal sources through time. Lithos, vol. 233, pp. 2–26, 2015, doi: 10.1016/j.lithos.2015.07.011.
[27] Goldfarb, R., & Groves, D. (2015). Orogenic gold : Common or evolving fl uid and metal sources through time. Lithos, vol. 233, pp. 2–26, 2015, doi: 10.1016/j.lithos.2015.07.011.
[28] Goldfarb, R., Groves, D., & Gardoll, S. (2001). Orogenic gold and geologic time : a global synthesis. Ore Geol Rev.
[29] Aliyari, F., Rastad,E., Goldfarb,R., & Abdollahi, J. (2014). Geochemistry of hydrothermal alteration at the Qolqoleh gold deposit , northern Sanandaj – Sirjan metamorphic belt , northwestern Iran : Vectors to high-grade ore bodies. J Geochem Explor, vol. 140, pp. 111–125, 2014, doi: 10.1016/j.gexplo.2014.01.007.
[30] Large, D., & Walcher, E. (1999). The Rammelsberg massive sulphide Cu-Zn-Pb-Ba-Deposit, Germany: an example of sediment-hosted, massive sulphide mineralization. Springer, vol. 34, no. 5–6, pp. 522–538, Jul. 1999, doi: 10.1007/s001260050218.
[31] Tombros, S., & Liu, J. (2014). “Origin of a barite-sul fi de ore deposit in the Mykonos intrusion , cyclades : Trace element , isotopic , fluid inclusion and raman spectroscopy evidence. Ore Geol Rev, vol. 67, pp. 139–157, 2015, doi: 10.1016/j.oregeorev.2014.11.016.
[32] Nykänen, V., Groves, D., & Gardoll, S.(2008). Reconnaissance-scale conceptual fuzzy-logic prospectivity modelling for iron oxide copper – gold deposits in the northern Fennoscandian Shield, Finland. Australian Journal of Earth Sciences, vol. 55, no. 1, pp. 25–38, Feb. 2008, doi: 10.1080/08120090701581372.
[33] Phillips, G., & Powell, R. (2012). Origin of Witwatersrand gold: A metamorphic devolatilisation-hydrothermal replacement model. Transactions of the Institutions of Mining and Metallurgy, Section B: Applied Earth Science, vol. 120, no. 3, 2012, doi: 10.1179/1743275812Y.0000000005.
[34] Hastie, E., Kontak, D., & Lafrance, B. (2020). Gold Remobilization: Insights from Gold Deposits in the Archean Swayze Greenstone Belt, Abitibi Subprovince, Canada. Economic Geology, vol. 115, no. 2, 2020, doi: 10.5382/econgeo.4709.
[35] Kwelwa, S., Dirks, P., Sanislav, I., Blenkinsop, T., & Kolling, S. (2018). Archaean gold mineralization in an extensional setting: The structural history of the Kukuluma and Matandani deposits, Geita Greenstone Belt, Tanzania. Minerals, vol. 8, no. 4, 2018, doi: 10.3390/min8040171.
[36] Austin, J., & Blenkinsop, T. (2007). The Cloncurry Lineament: Geophysical and geological evidence for a deep crustal structure in the Eastern Succession of the Mount Isa Inlier. Precambrian Res, vol. 163, no. 1–2, pp. 50–68, 2008, doi: 10.1016/j.precamres.2007.08.012.
[37] Li, Y., (2015). Zircon geochronology , geochemistry and stable isotopes of the Wang ’ ershan gold deposit , Jiaodong Peninsula , China. J Asian Earth Sci, vol. 113, pp. 695–710, 2015, doi: 10.1016/j.jseaes.2015.03.036
.[38] Santosh, M., Wilde, S., & Li, J. (2007). Timing of Paleoproterozoic ultrahigh-temperature metamorphism in the North China Craton : Evidence from SHRIMP U – Pb zircon geochronology. Precambrian Res, vol. 159, pp. 178–196, 2007, doi: 10.1016/j.precamres.2007.06.006.
[39]. Ganguly et al., (2016). Geochemical characteristics of gold bearing boninites and banded iron formations from Shimoga greenstone belt , India : Implications for gold genesis and hydrothermal processes in diverse tectonic settings. Ore Geol Rev, vol. 73, pp. 59–82, doi: 10.1016/j.oregeorev.2015.10.013. | ||
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