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Baimazhai |
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Yunnan, China |
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Ni Cu PGE PGM
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Super Porphyry Cu and Au
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The Baimazhai nickel-copper-(PGE) sulphide deposit is located in the Jinping region of Yunnan, in south-west China, approximately 180 km south of Kunming.
The deposit is hosted in a small mafic-ultramafic intrusion, which intruded Ordovician sandstone and slate. It lies towards the western margin of the Yangtze craton, which in the region comprises Paleoproterozoic schists and gneisses of the Kangding Complex, Proterozoic granites, overlain by shallow marine Sinian to Mesozoic sequences, including Ordovician sandstones and slates, Silurian dolomitic limestones and dolomite, Devonian limestone, Carboniferous limestone, Permian carbonate rich rocks and the extensive Emeishan continental flood basalts of the Emeishan Igneous Province. These are overlain in turn by Triassic continental and marine sediments (sandstones, conglomerates), and Jurassic to Cretaceous continental sequences. The entire pile has been deformed by a late Mesozoic, NW oriented overthrust system.
The Emeishan Igneous Province flood basalts cover an area of 0.5 million square km in southwestern China and northern Vietnam and have thicknesses ranging from several hundred metres to 5 km. Mafic and ultramafic intrusives are spatially and temporally related to the flood basalts.
In the Jinping region, the flood basalts are south of the major NW-SE trending, continental sacle Ailao Shan - Redi River fault zone and belong to the southernmost part of the Emeishan Igneous Province. They are up to 4500 m thick and lie between the early Permian Yangxin Formation and the Triassic Gejiu Formation. The flood basalts are mainly composed of massive aphyric or weakly plagioclase-phyric lavas with lesser interlayered volcanic breccia and tuff.
A group of small differentiated ultramafic to mafic intrusives associated with the flood basalts intrude Ordovician meta-sandstones in the vicinity of the Ailao Shan - Redi River fault zone in the Jinping region. One of these is the ~260 Ma Baimazhai mafic-ultramafic intrusive, a concentric, lens shaped body, about 530 m long, 190 m wide and 24 to 64 m thick which trends at 296° and dips 22°NE.
A massive sulfide ore body forms the core of the intrusion, surrounded by variably mineralised orthopyroxenite, websterite and barren gabbro. The proportion of gabbro 30%, websterite 30%, orthopyroxenite 20% and massive ore 20% (approximately).
In general the massive sulphide core passes outwards into orthopyroxenite then to websterite and the outer zone of gabbro. Both orthopyroxenite and websterite are variably mineralised, with net textured and disseminated ores, while the gabbro is generaly sulphide free. The massive sulphide orebody in the centre of the intrusion is around 425 m long, 40 to 70 m wide and 0.7 to 2.4 m thick.
The massive ores comprise more than 90% magmatic pyrrhotite, pentlandite and chalcopyrite. These massive ores contain 1.6 to 4.2, averaging 1.03% Ni and 0.4 to 6.5, averaging 0.81 wt.% Cu with low (85 to 524 ppb) total PGE.
The deposit is estimated to contain 50 000 t of Ni, 60% of which is in the massive sulphide core. This would amount to around 4.8 Mt of ore @ 1.03% Ni, 0.81% Cu. Resources of 6 Mt @ 1.23% Ni have also been quoted.
The most recent source geological information used to prepare this decription was dated: 2006.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Lu, Y., Lesher, C.M. and Deng, J., 2019 - Geochemistry and genesis of magmatic Ni-Cu-(PGE) and PGE-(Cu)-(Ni) deposits in China: in Ore Geology Reviews v.107, pp. 863-887.
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Pu, C., Qin, D., Nian, H., Zhang, X., Pirajno, F. and Fan, Z., 2007 - Geological and geochemical characteristics of the Baimazhai Ni-Cu-(PGE) sulphide deposit in Yunnan, China: in Chinese Journal of Geochemistry, v.26, pp. 374-383.
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Sun, X., Wang, S., Sun, W., Shi, G., Sun, Y., Xiong, D., Qu, W. and Du, A., 2008 - PGE geochemistry and Re-Os dating of massive sulfide ores from the Baimazhai Cu-Ni deposit, Yunnan province, China: in Lithos v.105, pp. 12-24.
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Tang, Q., Li, C., Liu, C., Xue, S.,Xu, S., Zhang, Y., Li, Z., Bao, J. and Song, H., 2023 - Contrasting magmatic controls on the genesis of Fe-Ti-V oxide deposits in the Emeishan large igneous province using apatite Sr-Nd isotopes and apatite-zircon trace elements: in Mineralium Deposita v.58, pp. 1279–1296. doi.org/10.1007/s00126-023-01180-0.
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Wang C Y and Zhou M-F, 2006 - Genesis of the Permian Baimazhai magmatic Ni-Cu-(PGE) sulfide deposit, Yunnan, SW China: in Mineralium Deposita v41 pp 771-783
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Zhang, X.S., Qin, D.X., Pirajno, F. and Nian, H., 2006 - Ar-Ar dating of Baimazhai nickel-copper-(PGE) sulphide deposit and its significance, southeast Yunnan Province, China: in Journal of China University of Mining and Technology (English Edition) v.16, pp. 200-205.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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